From: Guenter Roeck linux@roeck-us.net
[ Upstream commit 415fa1c7305dedbb345e2cc8ac91769bc1c83f1a ]
The DWC2 documentation states that transfers with zero data length should set the number of packets to 1 and the transfer length to 0. This is not currently the case for inbound transfers: the transfer length is set to the maximum packet length. This can have adverse effects if the chip actually does transfer data as it is programmed to do. Follow chip documentation and keep the transfer length set to 0 in that situation.
Fixes: 56f5b1cff22a1 ("staging: Core files for the DWC2 driver") Tested-by: Nicolas Saenz Julienne nsaenzjulienne@suse.de Reviewed-by: Douglas Anderson dianders@chromium.org Signed-off-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Nicolas Saenz Julienne nsaenzjulienne@suse.de Link: https://lore.kernel.org/r/20210113112052.17063-2-nsaenzjulienne@suse.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/usb/dwc2/hcd.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-)
diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c index a5c8329fd4625..56a35e0160392 100644 --- a/drivers/usb/dwc2/hcd.c +++ b/drivers/usb/dwc2/hcd.c @@ -1512,19 +1512,20 @@ static void dwc2_hc_start_transfer(struct dwc2_hsotg *hsotg, if (num_packets > max_hc_pkt_count) { num_packets = max_hc_pkt_count; chan->xfer_len = num_packets * chan->max_packet; + } else if (chan->ep_is_in) { + /* + * Always program an integral # of max packets + * for IN transfers. + * Note: This assumes that the input buffer is + * aligned and sized accordingly. + */ + chan->xfer_len = num_packets * chan->max_packet; } } else { /* Need 1 packet for transfer length of 0 */ num_packets = 1; }
- if (chan->ep_is_in) - /* - * Always program an integral # of max packets for IN - * transfers - */ - chan->xfer_len = num_packets * chan->max_packet; - if (chan->ep_type == USB_ENDPOINT_XFER_INT || chan->ep_type == USB_ENDPOINT_XFER_ISOC) /*