On 28/05/2021 16:04:46+0200, Thomas Petazzoni wrote:
> In commit 92af4fc6ec33 ("usb: musb: Fix suspend with devices
> connected for a64"), the logic to support the
> MUSB_QUIRK_B_DISCONNECT_99 quirk was modified to only conditionally
> schedule the musb->irq_work delayed work.
>
> This commit badly breaks ECM Gadget on AM335X. Indeed, with this
> commit, one can observe massive packet loss:
>
> $ ping 192.168.0.100
> ...
> 15 packets transmitted, 3 received, 80% packet loss, time 14316ms
>
> Reverting this commit brings back a properly functioning ECM
> Gadget. An analysis of the commit seems to indicate that a mistake was
> made: the previous code was not falling through into the
> MUSB_QUIRK_B_INVALID_VBUS_91, but now it is, unless the condition is
> taken.
>
> Changing the logic to be as it was before the problematic commit *and*
> only conditionally scheduling musb->irq_work resolves the regression:
>
> $ ping 192.168.0.100
> ...
> 64 packets transmitted, 64 received, 0% packet loss, time 64475ms
>
> Fixes: 92af4fc6ec33 ("usb: musb: Fix suspend with devices connected for a64")
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxx>
Tested-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> drivers/usb/musb/musb_core.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c
> index 8f09a387b773..4c8f0112481f 100644
> --- a/drivers/usb/musb/musb_core.c
> +++ b/drivers/usb/musb/musb_core.c
> @@ -2009,9 +2009,8 @@ static void musb_pm_runtime_check_session(struct musb *musb)
> schedule_delayed_work(&musb->irq_work,
> msecs_to_jiffies(1000));
> musb->quirk_retries--;
> - break;
> }
> - fallthrough;
> + break;
> case MUSB_QUIRK_B_INVALID_VBUS_91:
> if (musb->quirk_retries && !musb->flush_irq_work) {
> musb_dbg(musb,
> --
> 2.31.1
>
--
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
