This is a note to let you know that I've just added the patch titled usb: dwc2: Abort transaction after errors with unknown reason to the 4.19-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: usb-dwc2-abort-transaction-after-errors-with-unknown.patch and it can be found in the queue-4.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 1edbb301ff7831172cd56273c12bf4ef34be2fff Author: Guenter Roeck <linux@xxxxxxxxxxxx> Date: Wed Jan 13 12:20:50 2021 +0100 usb: dwc2: Abort transaction after errors with unknown reason [ Upstream commit f74b68c61cbc4b2245022fcce038509333d63f6f ] In some situations, the following error messages are reported. dwc2 ff540000.usb: dwc2_hc_chhltd_intr_dma: Channel 1 - ChHltd set, but reason is unknown dwc2 ff540000.usb: hcint 0x00000002, intsts 0x04000021 This is sometimes followed by: dwc2 ff540000.usb: dwc2_update_urb_state_abn(): trimming xfer length and then: WARNING: CPU: 0 PID: 0 at kernel/v4.19/drivers/usb/dwc2/hcd.c:2913 dwc2_assign_and_init_hc+0x98c/0x990 The warning suggests that an odd buffer address is to be used for DMA. After an error is observed, the receive buffer may be full (urb->actual_length >= urb->length). However, the urb is still left in the queue unless three errors were observed in a row. When it is queued again, the dwc2 hcd code translates this into a 1-block transfer. If urb->actual_length (ie the total expected receive length) is not DMA-aligned, the buffer pointer programmed into the chip will be unaligned. This results in the observed warning. To solve the problem, abort input transactions after an error with unknown cause if the entire packet was already received. This may be a bit drastic, but we don't really know why the transfer was aborted even though the entire packet was received. Aborting the transfer in this situation is less risky than accepting a potentially corrupted packet. With this patch in place, the 'ChHltd set' and 'trimming xfer length' messages are still observed, but there are no more transfer attempts with odd buffer addresses. Fixes: 151d0cbdbe860 ("usb: dwc2: make the scheduler handle excessive NAKs better") Cc: Boris ARZUR <boris@xxxxxxxxx> Cc: Douglas Anderson <dianders@xxxxxxxxxxxx> Tested-by: Nicolas Saenz Julienne <nsaenzjulienne@xxxxxxx> Reviewed-by: Douglas Anderson <dianders@xxxxxxxxxxxx> Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@xxxxxxx> Link: https://lore.kernel.org/r/20210113112052.17063-3-nsaenzjulienne@xxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/usb/dwc2/hcd_intr.c b/drivers/usb/dwc2/hcd_intr.c index a052d39b4375e..12819e019e13c 100644 --- a/drivers/usb/dwc2/hcd_intr.c +++ b/drivers/usb/dwc2/hcd_intr.c @@ -1977,6 +1977,18 @@ static void dwc2_hc_chhltd_intr_dma(struct dwc2_hsotg *hsotg, qtd->error_count++; dwc2_update_urb_state_abn(hsotg, chan, chnum, qtd->urb, qtd, DWC2_HC_XFER_XACT_ERR); + /* + * We can get here after a completed transaction + * (urb->actual_length >= urb->length) which was not reported + * as completed. If that is the case, and we do not abort + * the transfer, a transfer of size 0 will be enqueued + * subsequently. If urb->actual_length is not DMA-aligned, + * the buffer will then point to an unaligned address, and + * the resulting behavior is undefined. Bail out in that + * situation. + */ + if (qtd->urb->actual_length >= qtd->urb->length) + qtd->error_count = 3; dwc2_hcd_save_data_toggle(hsotg, chan, chnum, qtd); dwc2_halt_channel(hsotg, chan, qtd, DWC2_HC_XFER_XACT_ERR); }