On 24/08/23 14:50, Stanisław Kardach wrote:
Hi Adrian,
Thanks for reviewing our patches.
On Thu, Aug 24, 2023 at 1:47 PM Adrian Hunter <adrian.hunter@intel.com mailto:adrian.hunter@intel.com> wrote:
Hi Looks OK - a few minor comments below On 23/08/23 20:41, Sven van Ashbrook wrote: > To improve the r/w performance of GL9763E, the current driver inhibits LPM > negotiation while the device is active. > > This prevents a large number of SoCs from suspending, notably x86 systems If possible, can you give example of which SoCs / products > which use S0ix as the suspend mechanism: > 1. Userspace initiates s2idle suspend (e.g. via writing to > /sys/power/state) > 2. This switches the runtime_pm device state to active, which disables > LPM negotiation, then calls the "regular" suspend callback > 3. With LPM negotiation disabled, the bus cannot enter low-power state > 4. On a large number of SoCs, if the bus not in a low-power state, S0ix > cannot be entered, which in turn prevents the SoC from entering > suspend. > > Fix by re-enabling LPM negotiation in the device's suspend callback. > > Suggested-by: Stanislaw Kardach <skardach@google.com <mailto:skardach@google.com>> > Fixes: f9e5b33934ce ("mmc: host: Improve I/O read/write performance for GL9763E") > Cc: stable@vger.kernel.org <mailto:stable@vger.kernel.org> > Signed-off-by: Sven van Ashbrook <svenva@chromium.org <mailto:svenva@chromium.org>> > # on gladios device > # on 15590.0.0 with v5.10 and upstream (v6.4) kernels > 3 extraneous lines here - please remove > --- > > Changes in v2: > - improved symmetry and error path in s2idle suspend callback (internal review) > > drivers/mmc/host/sdhci-pci-gli.c | 102 +++++++++++++++++++------------ > 1 file changed, 64 insertions(+), 38 deletions(-) > > diff --git a/drivers/mmc/host/sdhci-pci-gli.c b/drivers/mmc/host/sdhci-pci-gli.c > index 1792665c9494a..19f577cc8bceb 100644 > --- a/drivers/mmc/host/sdhci-pci-gli.c > +++ b/drivers/mmc/host/sdhci-pci-gli.c > @@ -745,42 +745,6 @@ static u32 sdhci_gl9750_readl(struct sdhci_host *host, int reg) > return value; > } > > -#ifdef CONFIG_PM_SLEEP > -static int sdhci_pci_gli_resume(struct sdhci_pci_chip *chip) > -{ > - struct sdhci_pci_slot *slot = chip->slots[0]; > - > - pci_free_irq_vectors(slot->chip->pdev); > - gli_pcie_enable_msi(slot); > - > - return sdhci_pci_resume_host(chip); > -} > - > -static int sdhci_cqhci_gli_resume(struct sdhci_pci_chip *chip) > -{ > - struct sdhci_pci_slot *slot = chip->slots[0]; > - int ret; > - > - ret = sdhci_pci_gli_resume(chip); > - if (ret) > - return ret; > - > - return cqhci_resume(slot->host->mmc); > -} > - > -static int sdhci_cqhci_gli_suspend(struct sdhci_pci_chip *chip) > -{ > - struct sdhci_pci_slot *slot = chip->slots[0]; > - int ret; > - > - ret = cqhci_suspend(slot->host->mmc); > - if (ret) > - return ret; > - > - return sdhci_suspend_host(slot->host); > -} > -#endif > - > static void gl9763e_hs400_enhanced_strobe(struct mmc_host *mmc, > struct mmc_ios *ios) > { > @@ -1029,6 +993,68 @@ static int gl9763e_runtime_resume(struct sdhci_pci_chip *chip) > } > #endif > > +#ifdef CONFIG_PM_SLEEP > +static int sdhci_pci_gli_resume(struct sdhci_pci_chip *chip) > +{ > + struct sdhci_pci_slot *slot = chip->slots[0]; > + > + pci_free_irq_vectors(slot->chip->pdev); > + gli_pcie_enable_msi(slot); > + > + return sdhci_pci_resume_host(chip); > +} > + > +static int gl9763e_resume(struct sdhci_pci_chip *chip) > +{ > + struct sdhci_pci_slot *slot = chip->slots[0]; > + int ret; > + > + ret = sdhci_pci_gli_resume(chip); > + if (ret) > + return ret; > + > + ret = cqhci_resume(slot->host->mmc); > + if (ret) > + return ret; > + > + /* Disable LPM negotiation to bring device back in sync > + * with its runtime_pm state. > + */ I would prefer the comment style: /* * Blah, blah ... * Blah, blah, blah. */ > + gl9763e_set_low_power_negotiation(slot, false); > + > + return 0; > +} > + > +static int gl9763e_suspend(struct sdhci_pci_chip *chip) > +{ > + struct sdhci_pci_slot *slot = chip->slots[0]; > + int ret; > + > + /* Certain SoCs can suspend only with the bus in low- Ditto re comment style > + * power state, notably x86 SoCs when using S0ix. > + * Re-enable LPM negotiation to allow entering L1 state > + * and entering system suspend. > + */ > + gl9763e_set_low_power_negotiation(slot, true); Couldn't this be at the end of the function, save an error pathPlease correct me if I'm wrong but writing to device config space could trigger a side effect, so it's probably better to do it before calling functions suspending the device?
sdhci doesn't know anything about the bus. It is independent of PCI, so I can't see how it would make any difference. One of the people cc'ed might know more. Jason Lai (cc'ed) added it for runtime PM.
> + > + ret = cqhci_suspend(slot->host->mmc); > + if (ret) > + goto err_suspend; > + > + ret = sdhci_suspend_host(slot->host); > + if (ret) > + goto err_suspend_host; > + > + return 0; > + > +err_suspend_host: > + cqhci_resume(slot->host->mmc); > +err_suspend: > + gl9763e_set_low_power_negotiation(slot, false); > + return ret; > +} > +#endif > + > static int gli_probe_slot_gl9763e(struct sdhci_pci_slot *slot) > { > struct pci_dev *pdev = slot->chip->pdev; > @@ -1113,8 +1139,8 @@ const struct sdhci_pci_fixes sdhci_gl9763e = { > .probe_slot = gli_probe_slot_gl9763e, > .ops = &sdhci_gl9763e_ops, > #ifdef CONFIG_PM_SLEEP > - .resume = sdhci_cqhci_gli_resume, > - .suspend = sdhci_cqhci_gli_suspend, > + .resume = gl9763e_resume, > + .suspend = gl9763e_suspend, > #endif > #ifdef CONFIG_PM > .runtime_suspend = gl9763e_runtime_suspend,-- Best Regards, Stanisław Kardach
Hi,
On 24/08/23 20:18, Adrian Hunter wrote:
On 24/08/23 14:50, Stanis��aw Kardach wrote:
Hi Adrian,
Thanks for reviewing our patches.
On Thu, Aug 24, 2023 at 1:47���PM Adrian Hunter <adrian.hunter@intel.com mailto:adrian.hunter@intel.com> wrote:
Hi Looks OK - a few minor comments below On 23/08/23 20:41, Sven van Ashbrook wrote: > To improve the r/w performance of GL9763E, the current driver inhibits LPM > negotiation while the device is active. > > This prevents a large number of SoCs from suspending, notably x86 systems If possible, can you give example of which SoCs / products > which use S0ix as the suspend mechanism: > 1. Userspace initiates s2idle suspend (e.g. via writing to > /sys/power/state) > 2. This switches the runtime_pm device state to active, which disables > LPM negotiation, then calls the "regular" suspend callback > 3. With LPM negotiation disabled, the bus cannot enter low-power state > 4. On a large number of SoCs, if the bus not in a low-power state, S0ix > cannot be entered, which in turn prevents the SoC from entering > suspend. > > Fix by re-enabling LPM negotiation in the device's suspend callback. > > Suggested-by: Stanislaw Kardach <skardach@google.com <mailto:skardach@google.com>> > Fixes: f9e5b33934ce ("mmc: host: Improve I/O read/write performance for GL9763E") > Cc: stable@vger.kernel.org <mailto:stable@vger.kernel.org> > Signed-off-by: Sven van Ashbrook <svenva@chromium.org <mailto:svenva@chromium.org>> > # on gladios device > # on 15590.0.0 with v5.10 and upstream (v6.4) kernels > 3 extraneous lines here - please remove > --- > > Changes in v2: > - improved symmetry and error path in s2idle suspend callback (internal review) > > drivers/mmc/host/sdhci-pci-gli.c | 102 +++++++++++++++++++------------ > 1 file changed, 64 insertions(+), 38 deletions(-) > > diff --git a/drivers/mmc/host/sdhci-pci-gli.c b/drivers/mmc/host/sdhci-pci-gli.c > index 1792665c9494a..19f577cc8bceb 100644 > --- a/drivers/mmc/host/sdhci-pci-gli.c > +++ b/drivers/mmc/host/sdhci-pci-gli.c > @@ -745,42 +745,6 @@ static u32 sdhci_gl9750_readl(struct sdhci_host *host, int reg) > return value; > } > > -#ifdef CONFIG_PM_SLEEP > -static int sdhci_pci_gli_resume(struct sdhci_pci_chip *chip) > -{ > - struct sdhci_pci_slot *slot = chip->slots[0]; > - > - pci_free_irq_vectors(slot->chip->pdev); > - gli_pcie_enable_msi(slot); > - > - return sdhci_pci_resume_host(chip); > -} > - > -static int sdhci_cqhci_gli_resume(struct sdhci_pci_chip *chip) > -{ > - struct sdhci_pci_slot *slot = chip->slots[0]; > - int ret; > - > - ret = sdhci_pci_gli_resume(chip); > - if (ret) > - return ret; > - > - return cqhci_resume(slot->host->mmc); > -} > - > -static int sdhci_cqhci_gli_suspend(struct sdhci_pci_chip *chip) > -{ > - struct sdhci_pci_slot *slot = chip->slots[0]; > - int ret; > - > - ret = cqhci_suspend(slot->host->mmc); > - if (ret) > - return ret; > - > - return sdhci_suspend_host(slot->host); > -} > -#endif > - > static void gl9763e_hs400_enhanced_strobe(struct mmc_host *mmc, > struct mmc_ios *ios) > { > @@ -1029,6 +993,68 @@ static int gl9763e_runtime_resume(struct sdhci_pci_chip *chip) > } > #endif > > +#ifdef CONFIG_PM_SLEEP > +static int sdhci_pci_gli_resume(struct sdhci_pci_chip *chip) > +{ > + struct sdhci_pci_slot *slot = chip->slots[0]; > + > + pci_free_irq_vectors(slot->chip->pdev); > + gli_pcie_enable_msi(slot); > + > + return sdhci_pci_resume_host(chip); > +}
sdhci_pci_gli_resume() is the same as before. Is there any reason to move it here?
> + > +static int gl9763e_resume(struct sdhci_pci_chip *chip) > +{ > + struct sdhci_pci_slot *slot = chip->slots[0]; > + int ret; > + > + ret = sdhci_pci_gli_resume(chip); > + if (ret) > + return ret; > + > + ret = cqhci_resume(slot->host->mmc); > + if (ret) > + return ret; > + > + /* Disable LPM negotiation to bring device back in sync > + * with its runtime_pm state. > + */ I would prefer the comment style: /* * Blah, blah ... * Blah, blah, blah. */ > + gl9763e_set_low_power_negotiation(slot, false);
There is a situation for your reference. If `allow_runtime_pm' is set to false and the system resumes from suspend, GL9763E LPM negotiation will be always disabled on S0. GL9763E will stay L0 and never enter L1 because GL9763E LPM negotiation is disabled.
This patch enables allow_runtime_pm. The simple flow is gl9763e_suspend() -> LPM enabled -> gl9763e_resume() -> LPM disabled -> (a) (a) -+--> idle --> gl9763e_runtime_suspend() -> LPM enabled | +--> no idle -> gl9763e_runtime_resume() -> LPM disabled
This patch disables allow_runtime_pm. The simple flow is gl9763e_suspend() -> LPM enabled -> gl9763e_resume() -> LPM disabled (no runtime_pm)
Although that may not be the case with the current configuration, it's only a possibility.
> + > + return 0; > +} > + > +static int gl9763e_suspend(struct sdhci_pci_chip *chip) > +{ > + struct sdhci_pci_slot *slot = chip->slots[0]; > + int ret; > + > + /* Certain SoCs can suspend only with the bus in low- Ditto re comment style > + * power state, notably x86 SoCs when using S0ix. > + * Re-enable LPM negotiation to allow entering L1 state > + * and entering system suspend. > + */ > + gl9763e_set_low_power_negotiation(slot, true); Couldn't this be at the end of the function, save an error pathPlease correct me if I'm wrong but writing to device config space could trigger a side effect, so it's probably better to do it before calling functions suspending the device?
sdhci doesn't know anything about the bus. It is independent of PCI, so I can't see how it would make any difference. One of the people cc'ed might know more. Jason Lai (cc'ed) added it for runtime PM.
As far as I know, when disabling LPM negotiation, the GL9763E will stop entering L1. It doesn't other side effect. Does Jason.Lai and Victor.Shih have any comments or suggestions?
Best regards, Ben Chuang
> + > + ret = cqhci_suspend(slot->host->mmc); > + if (ret) > + goto err_suspend; > + > + ret = sdhci_suspend_host(slot->host); > + if (ret) > + goto err_suspend_host; > + > + return 0; > + > +err_suspend_host: > + cqhci_resume(slot->host->mmc); > +err_suspend: > + gl9763e_set_low_power_negotiation(slot, false); > + return ret; > +} > +#endif > + > static int gli_probe_slot_gl9763e(struct sdhci_pci_slot *slot) > { > struct pci_dev *pdev = slot->chip->pdev; > @@ -1113,8 +1139,8 @@ const struct sdhci_pci_fixes sdhci_gl9763e = { > .probe_slot = gli_probe_slot_gl9763e, > .ops = &sdhci_gl9763e_ops, > #ifdef CONFIG_PM_SLEEP > - .resume = sdhci_cqhci_gli_resume, > - .suspend = sdhci_cqhci_gli_suspend, > + .resume = gl9763e_resume, > + .suspend = gl9763e_suspend, > #endif > #ifdef CONFIG_PM > .runtime_suspend = gl9763e_runtime_suspend,-- Best Regards, Stanis��aw Kardach
Hi Ben,
Thanks for reviewing our patch.
On Mon, Aug 28, 2023 at 12:03 PM Ben Chuang benchuanggli@gmail.com wrote:
Hi,
On 24/08/23 20:18, Adrian Hunter wrote:
On 24/08/23 14:50, Stanisław Kardach wrote:
Hi Adrian,
Thanks for reviewing our patches.
On Thu, Aug 24, 2023 at 1:47 PM Adrian Hunter <adrian.hunter@intel.com mailto:adrian.hunter@intel.com> wrote:
Hi Looks OK - a few minor comments below On 23/08/23 20:41, Sven van Ashbrook wrote: > To improve the r/w performance of GL9763E, the current driver inhibits LPM > negotiation while the device is active. > > This prevents a large number of SoCs from suspending, notably x86 systems If possible, can you give example of which SoCs / products > which use S0ix as the suspend mechanism: > 1. Userspace initiates s2idle suspend (e.g. via writing to > /sys/power/state) > 2. This switches the runtime_pm device state to active, which disables > LPM negotiation, then calls the "regular" suspend callback > 3. With LPM negotiation disabled, the bus cannot enter low-power state > 4. On a large number of SoCs, if the bus not in a low-power state, S0ix > cannot be entered, which in turn prevents the SoC from entering > suspend. > > Fix by re-enabling LPM negotiation in the device's suspend callback. > > Suggested-by: Stanislaw Kardach <skardach@google.com <mailto:skardach@google.com>> > Fixes: f9e5b33934ce ("mmc: host: Improve I/O read/write performance for GL9763E") > Cc: stable@vger.kernel.org <mailto:stable@vger.kernel.org> > Signed-off-by: Sven van Ashbrook <svenva@chromium.org <mailto:svenva@chromium.org>> > # on gladios device > # on 15590.0.0 with v5.10 and upstream (v6.4) kernels > 3 extraneous lines here - please remove > --- > > Changes in v2: > - improved symmetry and error path in s2idle suspend callback (internal review) > > drivers/mmc/host/sdhci-pci-gli.c | 102 +++++++++++++++++++------------ > 1 file changed, 64 insertions(+), 38 deletions(-) > > diff --git a/drivers/mmc/host/sdhci-pci-gli.c b/drivers/mmc/host/sdhci-pci-gli.c > index 1792665c9494a..19f577cc8bceb 100644 > --- a/drivers/mmc/host/sdhci-pci-gli.c > +++ b/drivers/mmc/host/sdhci-pci-gli.c > @@ -745,42 +745,6 @@ static u32 sdhci_gl9750_readl(struct sdhci_host *host, int reg) > return value; > } > > -#ifdef CONFIG_PM_SLEEP > -static int sdhci_pci_gli_resume(struct sdhci_pci_chip *chip) > -{ > - struct sdhci_pci_slot *slot = chip->slots[0]; > - > - pci_free_irq_vectors(slot->chip->pdev); > - gli_pcie_enable_msi(slot); > - > - return sdhci_pci_resume_host(chip); > -} > - > -static int sdhci_cqhci_gli_resume(struct sdhci_pci_chip *chip) > -{ > - struct sdhci_pci_slot *slot = chip->slots[0]; > - int ret; > - > - ret = sdhci_pci_gli_resume(chip); > - if (ret) > - return ret; > - > - return cqhci_resume(slot->host->mmc); > -} > - > -static int sdhci_cqhci_gli_suspend(struct sdhci_pci_chip *chip) > -{ > - struct sdhci_pci_slot *slot = chip->slots[0]; > - int ret; > - > - ret = cqhci_suspend(slot->host->mmc); > - if (ret) > - return ret; > - > - return sdhci_suspend_host(slot->host); > -} > -#endif > - > static void gl9763e_hs400_enhanced_strobe(struct mmc_host *mmc, > struct mmc_ios *ios) > { > @@ -1029,6 +993,68 @@ static int gl9763e_runtime_resume(struct sdhci_pci_chip *chip) > } > #endif > > +#ifdef CONFIG_PM_SLEEP > +static int sdhci_pci_gli_resume(struct sdhci_pci_chip *chip) > +{ > + struct sdhci_pci_slot *slot = chip->slots[0]; > + > + pci_free_irq_vectors(slot->chip->pdev); > + gli_pcie_enable_msi(slot); > + > + return sdhci_pci_resume_host(chip); > +}sdhci_pci_gli_resume() is the same as before. Is there any reason to move it here?
To avoid having multiple #ifdef CONFIG_PM_SLEEP blocks. We can leave it, where it was if you prefer.
> + > +static int gl9763e_resume(struct sdhci_pci_chip *chip) > +{ > + struct sdhci_pci_slot *slot = chip->slots[0]; > + int ret; > + > + ret = sdhci_pci_gli_resume(chip); > + if (ret) > + return ret; > + > + ret = cqhci_resume(slot->host->mmc); > + if (ret) > + return ret; > + > + /* Disable LPM negotiation to bring device back in sync > + * with its runtime_pm state. > + */ I would prefer the comment style: /* * Blah, blah ... * Blah, blah, blah. */ > + gl9763e_set_low_power_negotiation(slot, false);There is a situation for your reference. If `allow_runtime_pm' is set to false and the system resumes from suspend, GL9763E LPM negotiation will be always disabled on S0. GL9763E will stay L0 and never enter L1 because GL9763E LPM negotiation is disabled.
This patch enables allow_runtime_pm. The simple flow is gl9763e_suspend() -> LPM enabled -> gl9763e_resume() -> LPM disabled -> (a) (a) -+--> idle --> gl9763e_runtime_suspend() -> LPM enabled | +--> no idle -> gl9763e_runtime_resume() -> LPM disabled
Is the lower branch of this sequence possible? I mean please correct me if I'm wrong but after the s2idle resume, devices are considered runtime active unless deemed otherwise, so gl_9763e_resume() -> fl9763e_runtime_resume() should not happen, right?
This patch disables allow_runtime_pm. The simple flow is gl9763e_suspend() -> LPM enabled -> gl9763e_resume() -> LPM disabled (no runtime_pm)
Although that may not be the case with the current configuration, it's only a possibility.
Actually last year there was a patch to improve R/W performance of GL9763E: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... If I'm reading the code right we're not modifying allow_runtime_pm, rather we're disabling the L1 negotiation in the same manner as the abovementioned patch does in the runtime PM flow. So in a way we're restoring whatever setting was there except a situation where the runtime PM was disabled from the start on the device and we do not restore the original state of the LPM negotiation fields. Not sure if such case is really possible.
> + > + return 0; > +} > + > +static int gl9763e_suspend(struct sdhci_pci_chip *chip) > +{ > + struct sdhci_pci_slot *slot = chip->slots[0]; > + int ret; > + > + /* Certain SoCs can suspend only with the bus in low- Ditto re comment style > + * power state, notably x86 SoCs when using S0ix. > + * Re-enable LPM negotiation to allow entering L1 state > + * and entering system suspend. > + */ > + gl9763e_set_low_power_negotiation(slot, true); Couldn't this be at the end of the function, save an error pathPlease correct me if I'm wrong but writing to device config space could trigger a side effect, so it's probably better to do it before calling functions suspending the device?
sdhci doesn't know anything about the bus. It is independent of PCI, so I can't see how it would make any difference. One of the people cc'ed might know more. Jason Lai (cc'ed) added it for runtime PM.
As far as I know, when disabling LPM negotiation, the GL9763E will stop entering L1. It doesn't other side effect. Does Jason.Lai and Victor.Shih have any comments or suggestions?
The reason we've put the LPM negotiation handling at the start of suspend and finish of resume was mostly for semantical reasons - first do device logic, then call base framework/module logic which might expect all the device-specific steps to be performed already. Maybe it does not make any difference in the real world for SDHCI controllers but it just seemed to look better. Also suspend and resume callbacks already have such ordering when it comes to cqhci_* and sdhci_* functions.
Best regards, Ben Chuang
> + > + ret = cqhci_suspend(slot->host->mmc); > + if (ret) > + goto err_suspend; > + > + ret = sdhci_suspend_host(slot->host); > + if (ret) > + goto err_suspend_host; > + > + return 0; > + > +err_suspend_host: > + cqhci_resume(slot->host->mmc); > +err_suspend: > + gl9763e_set_low_power_negotiation(slot, false); > + return ret; > +} > +#endif > + > static int gli_probe_slot_gl9763e(struct sdhci_pci_slot *slot) > { > struct pci_dev *pdev = slot->chip->pdev; > @@ -1113,8 +1139,8 @@ const struct sdhci_pci_fixes sdhci_gl9763e = { > .probe_slot = gli_probe_slot_gl9763e, > .ops = &sdhci_gl9763e_ops, > #ifdef CONFIG_PM_SLEEP > - .resume = sdhci_cqhci_gli_resume, > - .suspend = sdhci_cqhci_gli_suspend, > + .resume = gl9763e_resume, > + .suspend = gl9763e_suspend, > #endif > #ifdef CONFIG_PM > .runtime_suspend = gl9763e_runtime_suspend,-- Best Regards, Stanisław Kardach
Hi Ben, thank you for reviewing this patch. See below.
On Mon, Aug 28, 2023 at 6:03 AM Ben Chuang benchuanggli@gmail.com wrote:
There is a situation for your reference. If `allow_runtime_pm' is set to false and the system resumes from suspend, GL9763E LPM negotiation will be always disabled on S0. GL9763E will stay L0 and never enter L1 because GL9763E LPM negotiation is disabled.
This patch enables allow_runtime_pm. The simple flow is gl9763e_suspend() -> LPM enabled -> gl9763e_resume() -> LPM disabled -> (a) (a) -+--> idle --> gl9763e_runtime_suspend() -> LPM enabled | +--> no idle -> gl9763e_runtime_resume() -> LPM disabled
This patch disables allow_runtime_pm. The simple flow is gl9763e_suspend() -> LPM enabled -> gl9763e_resume() -> LPM disabled (no runtime_pm)
Although that may not be the case with the current configuration, it's only a possibility.
Thanks so much for bringing this up. We have discussed internally and as far as we know, the current patch will work correctly in all cases. Could you verify our argument please?
The following assumptions are key:
1. If CONFIG_PM is set, the runtime_pm framework is always present, i.e. there cannot exist a kernel which has PM but lacks runtime_pm. 2. The pm_runtime framework always makes sure the device is runtime active before calling XXX_suspend, waking it up if need be. So when XXX_suspend gets called, the device is always runtime active. 3. if CONFIG_PM is set, runtime_pm can only be disabled via echo on > /sys/devices/.../power/control, and then the runtime_pm framework always keeps the device in runtime active. In such case LPM negotiation is always disabled.
Using these assumptions, we get:
Runtime_pm allowed: —------------------ gl9763e_runtime_resume() -> LPM disabled -> gl9763e_suspend() -> LPM enabled -> gl9763e_resume() -> LPM disabled -> (a) (a) -+--> idle --> gl9763e_runtime_suspend() -> LPM enabled | +--> no idle -> nothing - already runtime active -> LPM disabled
Runtime_pm not allowed: —---------------------- gl9763e_runtime_resume() always called -> LPM always disabled gl9763e_suspend() -> LPM enabled -> gl9763e_resume() -> LPM disabled
In all above cases the LPM negotiation flag is correct.
sdhci doesn't know anything about the bus. It is independent of PCI, so I can't see how it would make any difference. One of the people cc'ed might know more. Jason Lai (cc'ed) added it for runtime PM.
As far as I know, when disabling LPM negotiation, the GL9763E will stop entering L1. It doesn't other side effect. Does Jason.Lai and Victor.Shih have any comments or suggestions?
Sounds like everyone assumes that you can freely change LPM negotiation on the PCIe bus after the cqhci_suspend() and sdhci_suspend_host() calls, so we will assume that too.
Hi Sven and Stanisław,
Sorry for Stanisław, I have seen your reply, but I only reply to this Regarding the location of the source codes, if the maintainers don't comment. I'll follow them too. :)
On Tue, Aug 29, 2023 at 6:51 AM Sven van Ashbrook svenva@chromium.org wrote:
Hi Ben, thank you for reviewing this patch. See below.
On Mon, Aug 28, 2023 at 6:03 AM Ben Chuang benchuanggli@gmail.com wrote:
There is a situation for your reference. If `allow_runtime_pm' is set to false and the system resumes from suspend, GL9763E LPM negotiation will be always disabled on S0. GL9763E will stay L0 and never enter L1 because GL9763E LPM negotiation is disabled.
This patch enables allow_runtime_pm. The simple flow is gl9763e_suspend() -> LPM enabled -> gl9763e_resume() -> LPM disabled -> (a) (a) -+--> idle --> gl9763e_runtime_suspend() -> LPM enabled | +--> no idle -> gl9763e_runtime_resume() -> LPM disabled
This patch disables allow_runtime_pm. The simple flow is gl9763e_suspend() -> LPM enabled -> gl9763e_resume() -> LPM disabled (no runtime_pm)
Although that may not be the case with the current configuration, it's only a possibility.
Thanks so much for bringing this up. We have discussed internally and as far as we know, the current patch will work correctly in all cases. Could you verify our argument please?
The following assumptions are key:
- If CONFIG_PM is set, the runtime_pm framework is always present, i.e. there
cannot exist a kernel which has PM but lacks runtime_pm. 2. The pm_runtime framework always makes sure the device is runtime active before calling XXX_suspend, waking it up if need be. So when XXX_suspend gets called, the device is always runtime active. 3. if CONFIG_PM is set, runtime_pm can only be disabled via echo on > /sys/devices/.../power/control, and then the runtime_pm framework always keeps the device in runtime active. In such case LPM negotiation is always disabled.
Using these assumptions, we get:
Runtime_pm allowed: —------------------ gl9763e_runtime_resume() -> LPM disabled -> gl9763e_suspend() -> LPM enabled -> gl9763e_resume() -> LPM disabled -> (a) (a) -+--> idle --> gl9763e_runtime_suspend() -> LPM enabled | +--> no idle -> nothing - already runtime active -> LPM disabled
Runtime_pm not allowed: —---------------------- gl9763e_runtime_resume() always called -> LPM always disabled gl9763e_suspend() -> LPM enabled -> gl9763e_resume() -> LPM disabled
In all above cases the LPM negotiation flag is correct.
My concern is that when runtime_pm is false, gl9763e is disabled LPM negotiation, gl9763e can't enter L1.x and s0ix may fail. It seems that runtime_pm will always exist and that's ok.
sdhci doesn't know anything about the bus. It is independent of PCI, so I can't see how it would make any difference. One of the people cc'ed might know more. Jason Lai (cc'ed) added it for runtime PM.
As far as I know, when disabling LPM negotiation, the GL9763E will stop entering L1. It doesn't other side effect. Does Jason.Lai and Victor.Shih have any comments or suggestions?
Sounds like everyone assumes that you can freely change LPM negotiation on the PCIe bus after the cqhci_suspend() and sdhci_suspend_host() calls, so we will assume that too.
Ah, I suppose cqhci_suspend() may need to be done first safely, then gl9763e_set_low_power_negotiation(slot, true).
Best regards, Ben Chuang
+ Rafael for advice on runtime_pm corner cases.
On Mon, Aug 28, 2023 at 10:48 PM Ben Chuang benchuanggli@gmail.com wrote:
My concern is that when runtime_pm is false, gl9763e is disabled LPM negotiation, gl9763e can't enter L1.x and s0ix may fail. It seems that runtime_pm will always exist and that's ok.
Thank you. I believe we can address your concern.
- XXX_suspend/XXX_resume (i.e. classic suspend/resume) depends on CONFIG_PM_SLEEP. This always selects CONFIG_PM. This always includes the runtime_pm framework. So, if XXX_suspend/XXX_resume gets called, the runtime_pm framework is always present, but may not be actively managing the device.
- "when runtime_pm is false" AFAIK the only way to disable runtime_pm when CONFIG_PM is set, is to write "on" to /sys/devices/.../power/control. See https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-devices-power In that case, the runtime_pm framework will activate the device, calling XXX_runtime_resume() if necessary. Are there other ways of disabling it?
- if /sys/devices/.../power/control is "on", then: gl9763e_runtime_resume() always called -> LPM always disabled gl9763e_suspend() -> LPM enabled -> gl9763e_resume() -> LPM disabled In between "classic" XXX_suspend and XXX_resume, LPM will be enabled, so the device can enter L1.x and S0ix.
And the LPM negotiation flags look correct. Does that address your concerns?
Hi, On Wed, Aug 30, 2023 at 12:35 AM Sven van Ashbrook svenva@chromium.org wrote:
- Rafael for advice on runtime_pm corner cases.
On Mon, Aug 28, 2023 at 10:48 PM Ben Chuang benchuanggli@gmail.com wrote:
My concern is that when runtime_pm is false, gl9763e is disabled LPM negotiation, gl9763e can't enter L1.x and s0ix may fail. It seems that runtime_pm will always exist and that's ok.
Thank you. I believe we can address your concern.
- XXX_suspend/XXX_resume (i.e. classic suspend/resume) depends on CONFIG_PM_SLEEP. This always selects CONFIG_PM. This always includes the runtime_pm framework. So, if XXX_suspend/XXX_resume gets called, the runtime_pm framework is always present, but may not be actively managing the device.
This is ok.
"when runtime_pm is false" AFAIK the only way to disable runtime_pm when CONFIG_PM is set, is to write "on" to /sys/devices/.../power/control. See https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-devices-power In that case, the runtime_pm framework will activate the device, calling XXX_runtime_resume() if necessary. Are there other ways of disabling it?
if /sys/devices/.../power/control is "on", then: gl9763e_runtime_resume() always called -> LPM always disabled gl9763e_suspend() -> LPM enabled -> gl9763e_resume() -> LPM disabled In between "classic" XXX_suspend and XXX_resume, LPM will be enabled, so the device can enter L1.x and S0ix.
In this cas, after gl9763e_resume(), it is LPM disabled. Is there no chance for gl9763e to enter L1.x again when the system is idle?
And the LPM negotiation flags look correct. Does that address your concerns?
Best regards, Ben Chuang
On Wed, Aug 30, 2023 at 4:27 AM Ben Chuang benchuanggli@gmail.com wrote:
Hi, On Wed, Aug 30, 2023 at 12:35 AM Sven van Ashbrook svenva@chromium.org wrote:
- Rafael for advice on runtime_pm corner cases.
On Mon, Aug 28, 2023 at 10:48 PM Ben Chuang benchuanggli@gmail.com wrote:
My concern is that when runtime_pm is false, gl9763e is disabled LPM negotiation, gl9763e can't enter L1.x and s0ix may fail. It seems that runtime_pm will always exist and that's ok.
Thank you. I believe we can address your concern.
- XXX_suspend/XXX_resume (i.e. classic suspend/resume) depends on CONFIG_PM_SLEEP. This always selects CONFIG_PM. This always includes the runtime_pm framework. So, if XXX_suspend/XXX_resume gets called, the runtime_pm framework is always present, but may not be actively managing the device.
This is ok.
"when runtime_pm is false" AFAIK the only way to disable runtime_pm when CONFIG_PM is set, is to write "on" to /sys/devices/.../power/control. See https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-devices-power In that case, the runtime_pm framework will activate the device, calling XXX_runtime_resume() if necessary. Are there other ways of disabling it?
if /sys/devices/.../power/control is "on", then: gl9763e_runtime_resume() always called -> LPM always disabled gl9763e_suspend() -> LPM enabled -> gl9763e_resume() -> LPM disabled In between "classic" XXX_suspend and XXX_resume, LPM will be enabled, so the device can enter L1.x and S0ix.
In this cas, after gl9763e_resume(), it is LPM disabled. Is there no chance for gl9763e to enter L1.x again when the system is idle?
With runtime PM disabled via sysfs, the short answer is not since https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i....
The longer answer is: 1. System boots up with LPM flags in PCI config space in default value (might be LPM enabled). 2.1. If runtime PM is disabled before first runtime suspend - registers will be left in their default state. 2.2. If runtime PM is disabled after first runtime suspend, the device will be woken up and the gl9763e runtime resume callback will disable LPM.
And the LPM negotiation flags look correct. Does that address your concerns?
Best regards, Ben Chuang
-- Best Regards, Stanisław Kardach
Hi Stanisław,
On Wed, Aug 30, 2023 at 3:32 PM Stanisław Kardach skardach@google.com wrote:
On Wed, Aug 30, 2023 at 4:27 AM Ben Chuang benchuanggli@gmail.com wrote:
Hi, On Wed, Aug 30, 2023 at 12:35 AM Sven van Ashbrook svenva@chromium.org wrote:
- Rafael for advice on runtime_pm corner cases.
On Mon, Aug 28, 2023 at 10:48 PM Ben Chuang benchuanggli@gmail.com wrote:
My concern is that when runtime_pm is false, gl9763e is disabled LPM negotiation, gl9763e can't enter L1.x and s0ix may fail. It seems that runtime_pm will always exist and that's ok.
Thank you. I believe we can address your concern.
- XXX_suspend/XXX_resume (i.e. classic suspend/resume) depends on CONFIG_PM_SLEEP. This always selects CONFIG_PM. This always includes the runtime_pm framework. So, if XXX_suspend/XXX_resume gets called, the runtime_pm framework is always present, but may not be actively managing the device.
This is ok.
"when runtime_pm is false" AFAIK the only way to disable runtime_pm when CONFIG_PM is set, is to write "on" to /sys/devices/.../power/control. See https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-devices-power In that case, the runtime_pm framework will activate the device, calling XXX_runtime_resume() if necessary. Are there other ways of disabling it?
if /sys/devices/.../power/control is "on", then: gl9763e_runtime_resume() always called -> LPM always disabled gl9763e_suspend() -> LPM enabled -> gl9763e_resume() -> LPM disabled In between "classic" XXX_suspend and XXX_resume, LPM will be enabled, so the device can enter L1.x and S0ix.
In this cas, after gl9763e_resume(), it is LPM disabled. Is there no chance for gl9763e to enter L1.x again when the system is idle?
With runtime PM disabled via sysfs, the short answer is not since https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i....
The longer answer is:
- System boots up with LPM flags in PCI config space in default value
(might be LPM enabled). 2.1. If runtime PM is disabled before first runtime suspend - registers will be left in their default state. 2.2. If runtime PM is disabled after first runtime suspend, the device will be woken up and the gl9763e runtime resume callback will disable LPM.
OK. Thank you for your answer.
Best Regards, Ben Chuang
And the LPM negotiation flags look correct. Does that address your concerns?
Best regards, Ben Chuang
-- Best Regards, Stanisław Kardach
On Tue, Aug 29, 2023 at 10:27 PM Ben Chuang benchuanggli@gmail.com wrote:
- if /sys/devices/.../power/control is "on", then:
<snip>
In this cas, after gl9763e_resume(), it is LPM disabled. Is there no chance for gl9763e to enter L1.x again when the system is idle?
AFAIK the only way to disable runtime_pm is to write: $ echo on > /sys/devices/.../power/control where $ echo auto > /sys/devices/.../power/control means: runtime_pm is actively managing the device, device can be "active" or "suspended". $ echo on > /sys/devices/.../power/control means: runtime_pm is not managing the device, device is "active" only.
In the "auto" case, we know what should happen: LPM negotiation is enabled when idle, disabled when active.
What should be the LPM negotiation state in the "on" case? We have to make a choice: a) LPM negotiation disabled: normal performance, high power consumption, OR b) LPM negotiation enabled: low performance, low power consumption
If userspace disables our device's runtime_pm by writing "on", it expects the device to be always-on. It should then expect a higher power consumption. It should then also expect a performance that is not-worse than the "auto" case.
So my suggestion would be to use (a), which is what this patch does.
Appreciate your thoughts.
Hi Sven van Ashbrook,
On Thu, Aug 31, 2023 at 4:14 AM Sven van Ashbrook svenva@chromium.org wrote:
On Tue, Aug 29, 2023 at 10:27 PM Ben Chuang benchuanggli@gmail.com wrote:
- if /sys/devices/.../power/control is "on", then:
<snip>
In this cas, after gl9763e_resume(), it is LPM disabled. Is there no chance for gl9763e to enter L1.x again when the system is idle?
AFAIK the only way to disable runtime_pm is to write: $ echo on > /sys/devices/.../power/control where $ echo auto > /sys/devices/.../power/control means: runtime_pm is actively managing the device, device can be "active" or "suspended". $ echo on > /sys/devices/.../power/control means: runtime_pm is not managing the device, device is "active" only.
In the "auto" case, we know what should happen: LPM negotiation is enabled when idle, disabled when active.
What should be the LPM negotiation state in the "on" case? We have to make a choice: a) LPM negotiation disabled: normal performance, high power consumption, OR b) LPM negotiation enabled: low performance, low power consumption
If userspace disables our device's runtime_pm by writing "on", it expects the device to be always-on. It should then expect a higher power consumption. It should then also expect a performance that is not-worse than the "auto" case.
So my suggestion would be to use (a), which is what this patch does.
Understood, I accept your suggestion.
Appreciate your thoughts.
Best regards, Ben Chuang
On Wed, Aug 30, 2023 at 8:34 PM Ben Chuang benchuanggli@gmail.com wrote:
Understood, I accept your suggestion.
Thanks so much for the detailed review, much appreciated ! I shall be posting a v3 later this week. I look forward to Genesys's review and/or Acked-by.
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Adrian Hunter -
Ben Chuang -
Stanisław Kardach -
Sven van Ashbrook