On Tue, Nov 12, 2019 at 4:47 AM Andreas Färber afaerber@suse.de wrote:
Am 12.11.19 um 08:29 schrieb Uwe Kleine-König:
On Tue, Nov 12, 2019 at 06:23:47AM +0100, Greg Kroah-Hartman wrote:
On Mon, Nov 11, 2019 at 09:10:41PM +0100, Andreas Färber wrote:
Am 11.11.19 um 07:40 schrieb Greg Kroah-Hartman:
On Mon, Nov 11, 2019 at 06:42:05AM +0100, Andreas Färber wrote:
Am 11.11.19 um 06:27 schrieb Greg Kroah-Hartman: > On Mon, Nov 11, 2019 at 05:56:09AM +0100, Andreas Färber wrote: >> Use of soc_device_to_device() in driver modules causes a build failure. >> Given that the helper is nicely documented in include/linux/sys_soc.h, >> let's export it as GPL symbol. > > I thought we were fixing the soc drivers to not need this. What > happened to that effort? I thought I had patches in my tree (or > someone's tree) that did some of this work already, such that this > symbol isn't needed anymore.
I do still see this function used in next-20191108 in drivers/soc/.
I'll be happy to adjust my RFC driver if someone points me to how!
Look at c31e73121f4c ("base: soc: Handle custom soc information sysfs entries") for how you can just use the default attributes for the soc to create the needed sysfs files, instead of having to do it "by hand" which is racy and incorrect.
Unrelated.
Given the current struct layout, a type cast might work (but ugly). Or if we stay with my current RFC driver design, we could use the platform_device instead of the soc_device (which would clutter the screen more than "soc soc0:") or resort to pr_info() w/o device.
Ick, no, don't cast blindly. What do you need the pointer for? Is this for in-tree code?
No, an RFC patchset: https://patchwork.kernel.org/cover/11224261/
As I indicated above, I used it for a dev_info(), which I can easily avoid by using pr_info() instead:
diff --git a/drivers/soc/realtek/chip.c b/drivers/soc/realtek/chip.c index e5078c6731fd..f9380e831659 100644 --- a/drivers/soc/realtek/chip.c +++ b/drivers/soc/realtek/chip.c @@ -178,8 +178,7 @@ static int rtd_soc_probe(struct platform_device *pdev)
platform_set_drvdata(pdev, soc_dev);
dev_info(soc_device_to_device(soc_dev),"%s %s (0x%08x) rev %s (0x%08x) detected\n",
pr_info("%s %s (0x%08x) rev %s (0x%08x) detected\n", soc_dev_attr->family, soc_dev_attr->soc_id, chip_id, soc_dev_attr->revision, chip_rev);First off, the driver should not be spitting out noise for when all goes well like this :)
I didn't follow the discussion closely, but I think I want to object here a bit. While I agree that each driver emitting some stuff to the log buffer is hardly helpful, seeing the exact SoC details is indeed useful at times. With my Debian kernel team member hat on, I'd say keep this information. This way the SoC details make it into kernel bug reports without effort on our side.
Seconded. For example, RTD1295 will support LSADC only from revision B00 on (and it's not the first time I'm seeing such things in the industry). So if a user complains, it will be helpful to see that information.
Referencing your Amlogic review, with all due respect for its authors, the common framework here just lets that information evaporate into the deeps of sysfs. People who know can check /sys/bus/soc/devices/soc0, but ordinary users will at most upload dmesg output to a Bugzilla ticket.
And it was precisely info-level boot output from the Amlogic GX driver that made me aware of this common framework and inspired me to later contribute such a driver elsewhere myself. That's not a bad effect. ;)
So if anything, we should standardize that output and move it into soc_device_register(): "<family> <soc_id> [rev <revision>] detected" with suitable NULL checks? (what I did above for Realtek, minus hex)
The info level seems correct to me - it allows people to use a different log_level if they only care about warnings or errors on the console; it's not debug info for that driver, except in my case the accompanying hex numbers that I'd be happy to drop in favor of standardization.
Another aspect here is that the overall amount of soc_device_register() users is just an estimated one third above the analysis shared before. In particular server platforms, be it arm64 or x86_64, that potentially have more than one SoC integrated in a multi-socket configuration, don't feed into this soc bus at all! Therefore my comment that dev_info()-printed "soc soc0:" is kind of useless if there's only one SoC on those boards. I'm not aware of any tool or a more common file aggregating this information, certainly not /proc/cpuinfo and I'm not aware of any special "lssoc" tool either. And if there's no ACPI/DMI driver feeding support-relevant information into this framework to be generally useful, I don't expect the big distros to spend time on improving its usability.
lshw? That works with info from DT, sysfs, and DMI. It did have some endian bugs (written for sparc/power) last time I looked at it 5+ years ago.
So if we move info output into base/soc.c, we could continue using dev_info() with "soc"-grep'able prefix in the hopes that someday we'll have more than one soc device on the bus and will need to distinguish; otherwise yes, pr_info() would change the output format for Amlogic (and so would a harmonization of the text), but does anyone really care in practice? Tools shouldn't be relying on its output format, and humans will understand equally either way.
Finally, arch/arm seems unique in that it has the machine_desc mechanism that allows individual SoCs to force creating their soc_device early and using it as parent for further DT-created platform_devices. With arm64 we've lost that ability, and nios2 is not using it either. A bad side effect (with SUSE hat on) is that this parent design pattern does not allow to build such drivers as modules, which means that distro configs using arm's multi-platform, e.g., CONFIG_ARCH_MULTI_V7 will get unnecessary code creep as new platforms get added over time (beyond the basic clk, pinctrl, tty and maybe timer). Even if it were possible to call into a driver module that early, using it as parent would seem to imply that all the references by its children would not allow to unload the module, which I'd consider a flawed design for such an "optional" read-once driver. If we want the device hierarchy to have a soc root then most DT based platforms will have a /soc DT node anyway (although no device_type = "soc") that we probably could have a device registered for in common code rather than each SoC platform handling that differently? That might then make soc_register_device() not the creator of the device (if pre-existent) but the supplier of data to that core device, which should then allow to unload the data provider with just the sysfs data disappearing until re-inserted (speeding up the develop-and-test cycle on say not-so-resource-constrained platforms).
I for one would like to for this to be consistent. Either we always have an SoC device parent or never. I wouldn't decide based on having a DT node or not either. Generally, we should always have MMIO devices under a bus node and perhaps more than one, but that doesn't always happen. I think building the drivers as modules is a good reason to do away with the parent device.
It would also allow getting rid of remaining of_platform_default_populate calls in arm platforms except for auxdata cases. Pretty much that's the ones you list below in arch/arm/.
On the other hand, one might argue that such information should just be parsed by EBBR-conformant bootloaders and be passed to the kernel via standard UEFI interfaces and DMI tables. But I'm not aware of Barebox having implemented any of that yet, and even for U-Boot (e.g., Realtek based consumer devices...) not everyone has the GPL sources or tools to update their bootloader. So, having the kernel we control gather information relevant to kernel developers does make some sense to me.
UEFI and DMI are orthogonal, right. You can't expect DMI on a UEFI+DT system.
Rob
Thoughts?
Regards, Andreas
P.S. Sorry that a seemingly trivial one-line 0-day fix derailed into this fundamental use case discussion.
arch/arm/mach-ep93xx/core.c: soc_dev = soc_device_register(soc_dev_attr); arch/arm/mach-imx/cpu.c: soc_dev = soc_device_register(soc_dev_attr); arch/arm/mach-mvebu/mvebu-soc-id.c: soc_dev = soc_device_register(soc_dev_attr); arch/arm/mach-mxs/mach-mxs.c: soc_dev = soc_device_register(soc_dev_attr); arch/arm/mach-omap2/id.c: soc_dev = soc_device_register(soc_dev_attr); arch/arm/mach-tegra/tegra.c: struct device *parent = tegra_soc_device_register(); arch/arm/mach-zynq/common.c: soc_dev = soc_device_register(soc_dev_attr); arch/nios2/platform/platform.c: soc_dev = soc_device_register(soc_dev_attr); drivers/soc/amlogic/meson-gx-socinfo.c: soc_dev = soc_device_register(soc_dev_attr); drivers/soc/amlogic/meson-mx-socinfo.c: soc_dev = soc_device_register(soc_dev_attr); drivers/soc/atmel/soc.c: soc_dev = soc_device_register(soc_dev_attr); drivers/soc/bcm/brcmstb/common.c: soc_dev = soc_device_register(soc_dev_attr); drivers/soc/fsl/guts.c: soc_dev = soc_device_register(&soc_dev_attr); drivers/soc/imx/soc-imx-scu.c: soc_dev = soc_device_register(soc_dev_attr); drivers/soc/imx/soc-imx8.c: soc_dev = soc_device_register(soc_dev_attr); drivers/soc/qcom/socinfo.c: qs->soc_dev = soc_device_register(&qs->attr); drivers/soc/realtek/chip.c: soc_dev = soc_device_register(soc_dev_attr); drivers/soc/renesas/renesas-soc.c: soc_dev = soc_device_register(soc_dev_attr); drivers/soc/samsung/exynos-chipid.c: soc_dev = soc_device_register(soc_dev_attr); drivers/soc/tegra/fuse/fuse-tegra.c: dev = soc_device_register(attr); drivers/soc/ux500/ux500-soc-id.c: soc_dev = soc_device_register(soc_dev_attr); drivers/soc/versatile/soc-integrator.c: soc_dev = soc_device_register(soc_dev_attr); drivers/soc/versatile/soc-realview.c: soc_dev = soc_device_register(soc_dev_attr);
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