On 22-10-19 02:07:17, Pawel Laszczak wrote:
> Patch modifies the TD_SIZE in TRB before ZLP TRB.
> The TD_SIZE in TRB before ZLP TRB must be set to 1 to force
> processing ZLP TRB by controller.
>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Fixes: 3d82904559f4 ("usb: cdnsp: cdns3 Add main part of Cadence USBSSP DRD Driver")
> Signed-off-by: Pawel Laszczak <pawell@xxxxxxxxxxx>
> ---
> drivers/usb/cdns3/cdnsp-ring.c | 15 ++++++++-------
> 1 file changed, 8 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/usb/cdns3/cdnsp-ring.c b/drivers/usb/cdns3/cdnsp-ring.c
> index 794e413800ae..4809d0e894bb 100644
> --- a/drivers/usb/cdns3/cdnsp-ring.c
> +++ b/drivers/usb/cdns3/cdnsp-ring.c
> @@ -1765,18 +1765,19 @@ static u32 cdnsp_td_remainder(struct cdnsp_device *pdev,
> struct cdnsp_request *preq,
> bool more_trbs_coming)
> {
> - u32 maxp, total_packet_count;
> -
> - /* One TRB with a zero-length data packet. */
> - if (!more_trbs_coming || (transferred == 0 && trb_buff_len == 0) ||
> - trb_buff_len == td_total_len)
> - return 0;
> + u32 maxp, total_packet_count, remainder;
>
> maxp = usb_endpoint_maxp(preq->pep->endpoint.desc);
> total_packet_count = DIV_ROUND_UP(td_total_len, maxp);
>
> /* Queuing functions don't count the current TRB into transferred. */
> - return (total_packet_count - ((transferred + trb_buff_len) / maxp));
> + remainder = (total_packet_count - ((transferred + trb_buff_len) / maxp));
> +
> + /* Before ZLP driver needs set TD_SIZE=1. */
> + if (!remainder && more_trbs_coming)
> + remainder = 1;
Without ZLP, TD_SIZE = 0 for the last TRB.
With ZLP, TD_SIZE = 1 for current TRB, and TD_SIZE = 0 for the next TRB
(the last zero-length packet) right?
Peter
> +
> + return remainder;
> }
>
> static int cdnsp_align_td(struct cdnsp_device *pdev,
> --
> 2.25.1
>
--
Thanks,
Peter Chen
