Re: [PATCH 6/6] usb: dwc3: gadget: Disable GUSB2PHYCFG.SUSPHY for End Transfer

[Mattijs Korpershoek <mkorpershoek@baylibre.com>]

Hi Alexander,

Thank you for the patch.

On ven., avril 12, 2024 at 22:26, "A. Sverdlin" <alexander.sverdlin@siemens.com> wrote:

> From: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
>
> Upstream Linux commit 3aa07f72894d.
>
> If there's a disconnection while operating in eSS, there may be a delay
> in VBUS drop response from the connector. In that case, the internal
> link state may drop to operate in usb2 speed while the controller thinks
> the VBUS is still high. The driver must make sure to disable
> GUSB2PHYCFG.SUSPHY when sending endpoint command while in usb2 speed.
> The End Transfer command may be called, and only that command needs to
> go through at this point. Let's keep it simple and unconditionally
> disable GUSB2PHYCFG.SUSPHY whenever we issue the command.
>
> This scenario is not seen in real hardware. In a rare case, our
> prototype type-c controller/interface may have a slow response
> triggerring this issue.
>
> Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
> Link: https://lore.kernel.org/r/5651117207803c26e2f22ddf4e5ce9e865dcf7c7.1668045468.git.Thinh.Nguyen@synopsys.com
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>

I've dropped Greg from the cc list as I understand by [1] that he
prefers to not receives responses on this.

Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>

[1] https://lore.kernel.org/r/all/2024041354-exciting-suggest-b896@gregkh/

> ---
>  drivers/usb/dwc3/gadget.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index c14d7870b9461..debfd4d6781db 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -316,7 +316,8 @@ int dwc3_send_gadget_ep_cmd(struct dwc3 *dwc, unsigned ep,
>  	 *
>  	 * DWC_usb3 3.30a and DWC_usb31 1.90a programming guide section 3.2.2
>  	 */
> -	if (dwc->gadget.speed <= USB_SPEED_HIGH) {
> +	if (dwc->gadget.speed <= USB_SPEED_HIGH ||
> +	    DWC3_DEPCMD_CMD(cmd) == DWC3_DEPCMD_ENDTRANSFER) {
>  		reg = dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0));
>  		if (unlikely(reg & DWC3_GUSB2PHYCFG_SUSPHY)) {
>  			saved_config |= DWC3_GUSB2PHYCFG_SUSPHY;
> -- 
> 2.44.0