On Mon, Mar 06, 2023, Wesley Cheng wrote:
> Previously, there was a 100uS delay inserted after issuing an end transfer
> command for specific controller revisions. This was due to the fact that
> there was a GUCTL2 bit field which enabled synchronous completion of the
> end transfer command once the CMDACT bit was cleared in the DEPCMD
> register. Since this bit does not exist for all controller revisions and
> the current implementation heavily relies on utizling the EndTransfer
> command completion interrupt, add the delay back in for uses where the
> interrupt on completion bit is not set, and increase the duration to 1ms
> for the controller to complete the command.
>
> An issue was seen where the USB request buffer was unmapped while the DWC3
> controller was still accessing the TRB. However, it was confirmed that the
> end transfer command was successfully submitted. (no end transfer timeout)
> In situations, such as dwc3_gadget_soft_disconnect() and
> __dwc3_gadget_ep_disable(), the dwc3_remove_request() is utilized, which
> will issue the end transfer command, and follow up with
> dwc3_gadget_giveback(). At least for the USB ep disable path, it is
> required for any pending and started requests to be completed and returned
> to the function driver in the same context of the disable call. Without
> the GUCTL2 bit, it is not ensured that the end transfer is completed before
> the buffers are unmapped.
>
> Fixes: cf2f8b63f7f1 ("usb: dwc3: gadget: Remove END_TRANSFER delay")
> Signed-off-by: Wesley Cheng <quic_wcheng@xxxxxxxxxxx>
> ---
> Changes in v5:
> - Updated commit text with more details
> - Added fixes tag
>
> Changes in v4:
> - Updated DWC3 revision check logic to look for !DWC3 based IP (ie DWC32 and
> DWC31 variants)
> - Fixed incorrect delay reference in comments
>
> Changes in v3:
> - Fixed subject title and modified commit text to reference the new 1ms
> delay
>
> Changes in v2:
> - Increase delay value to 1ms
> - Make this applicable to DWC32 revisions as well
>
> drivers/usb/dwc3/gadget.c | 14 +++++++++++---
> 1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 3c63fa97a680..cf5b4f49c3ed 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -1699,6 +1699,7 @@ static int __dwc3_gadget_get_frame(struct dwc3 *dwc)
> */
> static int __dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force, bool interrupt)
> {
> + struct dwc3 *dwc = dep->dwc;
> struct dwc3_gadget_ep_cmd_params params;
> u32 cmd;
> int ret;
> @@ -1722,10 +1723,13 @@ static int __dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force, bool int
> WARN_ON_ONCE(ret);
> dep->resource_index = 0;
>
> - if (!interrupt)
> + if (!interrupt) {
> + if (!DWC3_IP_IS(DWC3) || DWC3_VER_IS_PRIOR(DWC3, 310A))
> + mdelay(1);
> dep->flags &= ~DWC3_EP_TRANSFER_STARTED;
> - else if (!ret)
> + } else if (!ret) {
> dep->flags |= DWC3_EP_END_TRANSFER_PENDING;
> + }
>
> dep->flags &= ~DWC3_EP_DELAY_STOP;
> return ret;
> @@ -3774,7 +3778,11 @@ void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
> * enabled, the EndTransfer command will have completed upon
> * returning from this function.
> *
> - * This mode is NOT available on the DWC_usb31 IP.
> + * This mode is NOT available on the DWC_usb31 IP. In this
> + * case, if the IOC bit is not set, then delay by 1ms
> + * after issuing the EndTransfer command. This allows for the
> + * controller to handle the command completely before DWC3
> + * remove requests attempts to unmap USB request buffers.
> */
>
> __dwc3_stop_active_transfer(dep, force, interrupt);
Acked-by: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx>
Thanks,
Thinh
