On 11/11/2015 10:34 AM, Douglas Anderson wrote:
> In some cases, like when you've got a "Microsoft Wireless Keyboard 2000"
> connected to dwc2 with a hub, expected that we'll get some transfer
> errors sometimes. The controller is expected to try at least 3 times
> before giving up. See figure "Figure A-67. Normal HS CSPLIT 3 Strikes
> Smash" in the USB spec.
>
> The dwc2 controller has a way to support this by using the "EC_MC"
> field. The Raspberry Pi driver has logic for setting this right. See
> fiq_fsm_queue_split_transaction() in their "dwc_otg_hcd.c". Let's use
> the same logic.
>
> After making this change, we no longer get dropped characters from the
> above mentioned keyboard. Other devices on the same bus as the keyboard
> also behave more properly.
>
> Thanks for Julius Werner for the expert analysis and suggestions.
>
> Signed-off-by: Douglas Anderson <diand...@chromium.org>
> ---
> Repost without the WIP in tags (sorry for that).
>
> drivers/usb/dwc2/core.c | 14 ++++++++++++--
> 1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/dwc2/core.c b/drivers/usb/dwc2/core.c
> index ef73e498e98f..dcb4cd1d3b34 100644
> --- a/drivers/usb/dwc2/core.c
> +++ b/drivers/usb/dwc2/core.c
> @@ -1707,6 +1707,7 @@ void dwc2_hc_start_transfer(struct dwc2_hsotg *hsotg,
> u32 hcchar;
> u32 hctsiz = 0;
> u16 num_packets;
> + u32 ec_mc;
>
> if (dbg_hc(chan))
> dev_vdbg(hsotg->dev, "%s()\n", __func__);
> @@ -1743,6 +1744,13 @@ void dwc2_hc_start_transfer(struct dwc2_hsotg *hsotg,
>
> hctsiz |= chan->xfer_len << TSIZ_XFERSIZE_SHIFT &
> TSIZ_XFERSIZE_MASK;
> +
> + /* For split set ec_mc for immediate retries */
> + if (chan->ep_type == USB_ENDPOINT_XFER_INT ||
> + chan->ep_type == USB_ENDPOINT_XFER_ISOC)
> + ec_mc = 3;
> + else
> + ec_mc = 1;
> } else {
> if (dbg_hc(chan))
> dev_vdbg(hsotg->dev, "no split\n");
> @@ -1805,6 +1813,9 @@ void dwc2_hc_start_transfer(struct dwc2_hsotg *hsotg,
>
> hctsiz |= chan->xfer_len << TSIZ_XFERSIZE_SHIFT &
> TSIZ_XFERSIZE_MASK;
> +
> + /* The ec_mc gets the multi_count for non-split */
> + ec_mc = chan->multi_count;
> }
>
> chan->start_pkt_count = num_packets;
> @@ -1855,8 +1866,7 @@ void dwc2_hc_start_transfer(struct dwc2_hsotg *hsotg,
>
> hcchar = dwc2_readl(hsotg->regs + HCCHAR(chan->hc_num));
> hcchar &= ~HCCHAR_MULTICNT_MASK;
> - hcchar |= chan->multi_count << HCCHAR_MULTICNT_SHIFT &
> - HCCHAR_MULTICNT_MASK;
> + hcchar |= (ec_mc << HCCHAR_MULTICNT_SHIFT) & HCCHAR_MULTICNT_MASK;
> dwc2_hc_set_even_odd_frame(hsotg, chan, &hcchar);
>
> if (hcchar & HCCHAR_CHDIS)
>
Acked-by: John Youn <johny...@synopsys.com>
Regards,
John
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