On Thu, 2021-08-05 at 13:39 +0800, Ikjoon Jang wrote:
> Currently xhci-mtk needs software-managed bandwidth allocation for
> periodic endpoints, it allocates the microframe index for the first
> start-split packet for each endpoint. As this index allocation logic
> should avoid the conflicts with other full/low-speed periodic
> endpoints,
> it uses the worst case byte budgets on high-speed bus bandwidth
> For example, for an isochronos IN endpoint with 192 bytes budget,
> it will consume the whole 4 u-frames(188 * 4) while the actual
> full-speed bus budget should be just 192bytes.
>
> This patch changes the low/full-speed bandwidth allocation logic
> to use "approximate" best case budget for lower speed bandwidth
> management. For the same endpoint from the above example, the
> approximate best case budget is now reduced to (188 * 2) bytes.
>
> Without this patch, many usb audio headsets with 3 interfaces
> (audio input, audio output, and HID) cannot be configured
> on xhci-mtk.
>
> Signed-off-by: Ikjoon Jang <ikjn@xxxxxxxxxxxx>
> ---
>
> drivers/usb/host/xhci-mtk-sch.c | 20 +++++++++++++-------
> 1 file changed, 13 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/usb/host/xhci-mtk-sch.c b/drivers/usb/host/xhci-
> mtk-sch.c
> index f9b4d27ce449..46cbf5d54f4f 100644
> --- a/drivers/usb/host/xhci-mtk-sch.c
> +++ b/drivers/usb/host/xhci-mtk-sch.c
> @@ -459,16 +459,17 @@ static int check_fs_bus_bw(struct
> mu3h_sch_ep_info *sch_ep, int offset)
> u32 num_esit, tmp;
> int base;
> int i, j;
> + u8 uframes = DIV_ROUND_UP(sch_ep->maxpkt, FS_PAYLOAD_MAX);
>
> num_esit = XHCI_MTK_MAX_ESIT / sch_ep->esit;
> +
> + if (sch_ep->ep_type == INT_IN_EP || sch_ep->ep_type ==
> ISOC_IN_EP)
> + offset++;
> +
> for (i = 0; i < num_esit; i++) {
> base = offset + i * sch_ep->esit;
>
> - /*
> - * Compared with hs bus, no matter what ep type,
> - * the hub will always delay one uframe to send data
> - */
> - for (j = 0; j < sch_ep->cs_count; j++) {
> + for (j = 0; j < uframes; j++) {
Please don't calculate new value, should use the value calculated by
check_sch_tt().
See usb2.0 spec Figure 11-64, sometime will use 2 extra CS.
> tmp = tt->fs_bus_bw[base + j] + sch_ep-
> >bw_cost_per_microframe;
> if (tmp > FS_PAYLOAD_MAX)
> return -ESCH_BW_OVERFLOW;
> @@ -546,6 +547,8 @@ static void update_sch_tt(struct mu3h_sch_ep_info
> *sch_ep, bool used)
> u32 base, num_esit;
> int bw_updated;
> int i, j;
> + int offset = sch_ep->offset;
> + u8 uframes = DIV_ROUND_UP(sch_ep->maxpkt, FS_PAYLOAD_MAX);
>
> num_esit = XHCI_MTK_MAX_ESIT / sch_ep->esit;
>
> @@ -554,10 +557,13 @@ static void update_sch_tt(struct
> mu3h_sch_ep_info *sch_ep, bool used)
> else
> bw_updated = -sch_ep->bw_cost_per_microframe;
>
> + if (sch_ep->ep_type == INT_IN_EP || sch_ep->ep_type ==
> ISOC_IN_EP)
> + offset++;
> +
> for (i = 0; i < num_esit; i++) {
> - base = sch_ep->offset + i * sch_ep->esit;
> + base = offset + i * sch_ep->esit;
>
> - for (j = 0; j < sch_ep->cs_count; j++)
> + for (j = 0; j < uframes; j++)
> tt->fs_bus_bw[base + j] += bw_updated;
> }
>
