On 25-02-06 18:29:36, Siddharth Vadapalli wrote:
When the device is in a low power state, access to the following registers takes a long time:
- EP_CFG
- EP_TRADDR
- EP_CMD
- EP_SEL
- EP_STS
- USB_CONF
To address this, the fast register access feature can be enabled by setting PUSB_PWR_FST_REG_ACCESS bit of the USB_PWR register, which allows quick access by software. Software is expected to poll on PUSB_PWR_FST_REG_ACCESS_STAT to ensure that fast register access has been enabled by the controller. Attempting to access any of the aforementioned registers after setting PUSB_PWR_FST_REG_ACCESS but before PUSB_PWR_FST_REG_ACCESS_STAT has been set will result in undefined behavior and potentially result in system hang.
Hence, poll on PUSB_PWR_FST_REG_ACCESS_STAT before proceeding with gadget configuration, and exit if it cannot be enabled.
Fixes: b5148d946f45 ("usb: cdns3: gadget: set fast access bit") Cc: stable@vger.kernel.org Signed-off-by: Siddharth Vadapalli s-vadapalli@ti.com
Hello,
This patch is based on commit 92514ef226f5 Merge tag 'for-6.14-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux of Mainline Linux.
Regards, Siddharth.
drivers/usb/cdns3/cdns3-gadget.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c index fd1beb10bba7..b62691944272 100644 --- a/drivers/usb/cdns3/cdns3-gadget.c +++ b/drivers/usb/cdns3/cdns3-gadget.c @@ -2971,8 +2971,6 @@ static void cdns3_gadget_config(struct cdns3_device *priv_dev) /* enable generic interrupt*/ writel(USB_IEN_INIT, ®s->usb_ien); writel(USB_CONF_CLK2OFFDS | USB_CONF_L1DS, ®s->usb_conf);
- /* keep Fast Access bit */
- writel(PUSB_PWR_FST_REG_ACCESS, &priv_dev->regs->usb_pwr);
cdns3_configure_dmult(priv_dev, NULL); } @@ -2990,6 +2988,8 @@ static int cdns3_gadget_udc_start(struct usb_gadget *gadget, struct cdns3_device *priv_dev = gadget_to_cdns3_device(gadget); unsigned long flags; enum usb_device_speed max_speed = driver->max_speed;
- int ret;
- u32 reg;
spin_lock_irqsave(&priv_dev->lock, flags); priv_dev->gadget_driver = driver; @@ -2997,6 +2997,20 @@ static int cdns3_gadget_udc_start(struct usb_gadget *gadget, /* limit speed if necessary */ max_speed = min(driver->max_speed, gadget->max_speed);
- /* keep Fast Access bit */
- writel(PUSB_PWR_FST_REG_ACCESS, &priv_dev->regs->usb_pwr);
- reg = readl(&priv_dev->regs->usb_pwr);
- if (!(reg & PUSB_PWR_FST_REG_ACCESS_STAT)) {
ret = readl_poll_timeout_atomic(&priv_dev->regs->usb_pwr, reg,(reg & PUSB_PWR_FST_REG_ACCESS_STAT),10, 1000);if (ret) {dev_err(priv_dev->dev, "Failed to enable fast access\n");spin_unlock_irqrestore(&priv_dev->lock, flags);return ret;}- }
- switch (max_speed) { case USB_SPEED_FULL: writel(USB_CONF_SFORCE_FS, &priv_dev->regs->usb_conf);
Hi Siddharth,
Would you please keep this change at cdns3_gadget_config in case the controller is power lost during the system suspend?
Peter