[PATCH v2] usb: dwc3: xilinx: make sure pipe clock is deselected in usb2 only mode

[Peter Korsgaard]

On 11/18/24 16:08, Radhey Shyam Pandey wrote:
> From: Neal Frager <neal.frager at 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

2nd "is " should be dropped. This sounds a bit confusing to me as the 
PHY is on-chip on zynqmp, maybe you are referring to a reference clock 
input to the PS-GTR instead?


> 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")
> Cc: stable at vger.kernel.org
> Signed-off-by: Neal Frager <neal.frager at amd.com>
> Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey at amd.com>
> ---
> Changes for v2:
> - Add stable at vger.kernel.org in CC.

Other than that looks good, thanks.

Acked-by: Peter Korsgaard <peter at korsgaard.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

-- 
Bye, Peter Korsgaard