From: Neal Frager <neal.frager@amd.com>

When the USB3 PHY is not defined in the Linux device tree, there could
still be a case where there is a USB3 PHY is active on the board and
enabled by the first stage bootloader.  If serdes clock is being used
then the USB will fail to enumerate devices in 2.0 only mode.

To solve this, make sure that the PIPE clock is deselected whenever the
USB3 PHY is not defined and guarantees that the USB2 only mode will work
in all cases.

Fixes: 9678f3361afc ("usb: dwc3: xilinx: Skip resets and USB3 register settings for USB2.0 mode")
Signed-off-by: Neal Frager <neal.frager@amd.com>
Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@amd.com>
---
 drivers/usb/dwc3/dwc3-xilinx.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/dwc3/dwc3-xilinx.c b/drivers/usb/dwc3/dwc3-xilinx.c
index e3738e1610db..a33a42ba0249 100644
--- a/drivers/usb/dwc3/dwc3-xilinx.c
+++ b/drivers/usb/dwc3/dwc3-xilinx.c
@@ -121,8 +121,11 @@ static int dwc3_xlnx_init_zynqmp(struct dwc3_xlnx *priv_data)
 	 * in use but the usb3-phy entry is missing from the device tree.
 	 * Therefore, skip these operations in this case.
 	 */
-	if (!priv_data->usb3_phy)
+	if (!priv_data->usb3_phy) {
+		/* Deselect the PIPE Clock Select bit in FPD PIPE Clock register */
+		writel(PIPE_CLK_DESELECT, priv_data->regs + XLNX_USB_FPD_PIPE_CLK);
 		goto skip_usb3_phy;
+	}
 
 	crst = devm_reset_control_get_exclusive(dev, "usb_crst");
 	if (IS_ERR(crst)) {

base-commit: 744cf71b8bdfcdd77aaf58395e068b7457634b2c
-- 
2.34.1

On Sat, Nov 16, 2024 at 12:01:00AM +0530, Radhey Shyam Pandey wrote:
> From: Neal Frager <neal.frager@amd.com>
> 
> When the USB3 PHY is not defined in the Linux device tree, there could
> still be a case where there is a USB3 PHY is active on the board and
> enabled by the first stage bootloader.  If serdes clock is being used
> then the USB will fail to enumerate devices in 2.0 only mode.
> 
> To solve this, make sure that the PIPE clock is deselected whenever the
> USB3 PHY is not defined and guarantees that the USB2 only mode will work
> in all cases.
> 
> Fixes: 9678f3361afc ("usb: dwc3: xilinx: Skip resets and USB3 register settings for USB2.0 mode")
> Signed-off-by: Neal Frager <neal.frager@amd.com>
> Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@amd.com>
> ---
>  drivers/usb/dwc3/dwc3-xilinx.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/dwc3/dwc3-xilinx.c b/drivers/usb/dwc3/dwc3-xilinx.c
> index e3738e1610db..a33a42ba0249 100644
> --- a/drivers/usb/dwc3/dwc3-xilinx.c
> +++ b/drivers/usb/dwc3/dwc3-xilinx.c
> @@ -121,8 +121,11 @@ static int dwc3_xlnx_init_zynqmp(struct dwc3_xlnx *priv_data)
>  	 * in use but the usb3-phy entry is missing from the device tree.
>  	 * Therefore, skip these operations in this case.
>  	 */
> -	if (!priv_data->usb3_phy)
> +	if (!priv_data->usb3_phy) {
> +		/* Deselect the PIPE Clock Select bit in FPD PIPE Clock register */
> +		writel(PIPE_CLK_DESELECT, priv_data->regs + XLNX_USB_FPD_PIPE_CLK);
>  		goto skip_usb3_phy;
> +	}
>  
>  	crst = devm_reset_control_get_exclusive(dev, "usb_crst");
>  	if (IS_ERR(crst)) {
> 
> base-commit: 744cf71b8bdfcdd77aaf58395e068b7457634b2c
> -- 
> 2.34.1
> 
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
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- You have marked a patch with a "Fixes:" tag for a commit that is in an
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  Documentation/process/stable-kernel-rules.rst file for how to resolve
  this.

If you wish to discuss this problem further, or you have questions about
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thanks,

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