Re: [RFC v4 PATCH] usb: xhci-mtk: improve bandwidth scheduling with TT

[Ikjoon Jang]

On Mon, Feb 8, 2021 at 11:27 AM Chunfeng Yun <chunfeng.yun@xxxxxxxxxxxx> wrote:
>
> When the USB headset is plug into an external hub, sometimes
> can't set config due to not enough bandwidth, so need improve
> LS/FS INT/ISOC bandwidth scheduling with TT.
>
> Fixes: 08e469de87a2 ("usb: xhci-mtk: supports bandwidth scheduling with multi-TT")
> Signed-off-by: Yaqii Wu <yaqii.wu@xxxxxxxxxxxx>
> Signed-off-by: Chunfeng Yun <chunfeng.yun@xxxxxxxxxxxx>

Tested-by: Ikjoon Jang <ikjn@xxxxxxxxxxxx>

> ---
>  drivers/usb/host/xhci-mtk-sch.c | 270 +++++++++++++++++++++++---------
>  drivers/usb/host/xhci-mtk.h     |   8 +-
>  2 files changed, 201 insertions(+), 77 deletions(-)
>
> diff --git a/drivers/usb/host/xhci-mtk-sch.c b/drivers/usb/host/xhci-mtk-sch.c
> index b45e5bf08997..f3cdfcf4e5bf 100644
> --- a/drivers/usb/host/xhci-mtk-sch.c
> +++ b/drivers/usb/host/xhci-mtk-sch.c
> @@ -32,6 +32,35 @@
>  #define EP_BOFFSET(p)  ((p) & 0x3fff)
>  #define EP_BREPEAT(p)  (((p) & 0x7fff) << 16)
>
> +enum mtk_sch_err_type {
> +       SCH_SUCCESS = 0,
> +       SCH_ERR_Y6,
> +       SCH_SS_OVERLAP,
> +       SCH_CS_OVERFLOW,
> +       SCH_BW_OVERFLOW,
> +       SCH_FIXME,
> +};
> +
> +static char *sch_error_string(enum mtk_sch_err_type error)
> +{
> +       switch (error) {
> +       case SCH_SUCCESS:
> +               return "Success";
> +       case SCH_ERR_Y6:
> +               return "Can't schedule Start-Split in Y6";
> +       case SCH_SS_OVERLAP:
> +               return "Can't find a suitable Start-Split location";
> +       case SCH_CS_OVERFLOW:
> +               return "The last Complete-Split is greater than 7";
> +       case SCH_BW_OVERFLOW:
> +               return "Bandwidth exceeds the max limit";
> +       case SCH_FIXME:
> +               return "FIXME, to be resolved";
> +       default:
> +               return "Unknown error type";
> +       }
> +}
> +
>  static int is_fs_or_ls(enum usb_device_speed speed)
>  {
>         return speed == USB_SPEED_FULL || speed == USB_SPEED_LOW;
> @@ -81,11 +110,22 @@ static u32 get_esit(struct xhci_ep_ctx *ep_ctx)
>         return esit;
>  }
>
> +static u32 get_bw_boundary(enum usb_device_speed speed)
> +{
> +       switch (speed) {
> +       case USB_SPEED_SUPER_PLUS:
> +               return SSP_BW_BOUNDARY;
> +       case USB_SPEED_SUPER:
> +               return SS_BW_BOUNDARY;
> +       default:
> +               return HS_BW_BOUNDARY;
> +       }
> +}
> +
>  static struct mu3h_sch_tt *find_tt(struct usb_device *udev)
>  {
>         struct usb_tt *utt = udev->tt;
>         struct mu3h_sch_tt *tt, **tt_index, **ptt;
> -       unsigned int port;
>         bool allocated_index = false;
>
>         if (!utt)
> @@ -107,10 +147,9 @@ static struct mu3h_sch_tt *find_tt(struct usb_device *udev)
>                         utt->hcpriv = tt_index;
>                         allocated_index = true;
>                 }
> -               port = udev->ttport - 1;
> -               ptt = &tt_index[port];
> +
> +               ptt = &tt_index[udev->ttport - 1];
>         } else {
> -               port = 0;
>                 ptt = (struct mu3h_sch_tt **) &utt->hcpriv;
>         }
>
> @@ -125,8 +164,7 @@ static struct mu3h_sch_tt *find_tt(struct usb_device *udev)
>                         return ERR_PTR(-ENOMEM);
>                 }
>                 INIT_LIST_HEAD(&tt->ep_list);
> -               tt->usb_tt = utt;
> -               tt->tt_port = port;
> +
>                 *ptt = tt;
>         }
>
> @@ -206,6 +244,15 @@ static struct mu3h_sch_ep_info *create_sch_ep(struct usb_device *udev,
>         return sch_ep;
>  }
>
> +static void delete_sch_ep(struct usb_device *udev, struct mu3h_sch_ep_info *sch_ep)
> +{
> +       if (sch_ep->sch_tt)
> +               drop_tt(udev);
> +
> +       list_del(&sch_ep->endpoint);
> +       kfree(sch_ep);
> +}
> +
>  static void setup_sch_info(struct usb_device *udev,
>                 struct xhci_ep_ctx *ep_ctx, struct mu3h_sch_ep_info *sch_ep)
>  {
> @@ -375,21 +422,55 @@ static void update_bus_bw(struct mu3h_sch_bw_info *sch_bw,
>                                         sch_ep->bw_budget_table[j];
>                 }
>         }
> -       sch_ep->allocated = used;
>  }
>
> -static int check_sch_tt(struct usb_device *udev,
> -       struct mu3h_sch_ep_info *sch_ep, u32 offset)
> +static int check_fs_bus_bw(struct mu3h_sch_ep_info *sch_ep, int offset)
> +{
> +       struct mu3h_sch_tt *tt = sch_ep->sch_tt;
> +       u32 num_esit, base;
> +       u32 i, j;
> +       u32 tmp;
> +
> +       num_esit = XHCI_MTK_MAX_ESIT / sch_ep->esit;
> +
> +       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 us. As described in the figure below.
> +                */
> +               if (sch_ep->ep_type == ISOC_OUT_EP) {
> +                       for (j = 0; j < sch_ep->num_budget_microframes; j++) {
> +                               tmp = tt->fs_bus_bw[base + 1 + j]
> +                                       + sch_ep->bw_cost_per_microframe;
> +
> +                               if (tmp > FS_PAYLOAD_MAX)
> +                                       return SCH_BW_OVERFLOW;
> +                       }
> +               } else {
> +                       for (j = 0; j < sch_ep->cs_count; j++) {
> +                               tmp = tt->fs_bus_bw[base + 1 + j]
> +                                       + sch_ep->bw_cost_per_microframe;
> +
> +                               if (tmp > FS_PAYLOAD_MAX)
> +                                       return SCH_BW_OVERFLOW;
> +                       }
> +               }
> +       }
> +       return SCH_SUCCESS;
> +}
> +
> +static int check_sch_tt(struct mu3h_sch_ep_info *sch_ep, int offset)
>  {
>         struct mu3h_sch_tt *tt = sch_ep->sch_tt;
>         u32 extra_cs_count;
> -       u32 fs_budget_start;
>         u32 start_ss, last_ss;
>         u32 start_cs, last_cs;
> -       int i;
> +       u32 i;
>
>         start_ss = offset % 8;
> -       fs_budget_start = (start_ss + 1) % 8;
>
>         if (sch_ep->ep_type == ISOC_OUT_EP) {
>                 last_ss = start_ss + sch_ep->cs_count - 1;
> @@ -399,12 +480,12 @@ static int check_sch_tt(struct usb_device *udev,
>                  * must never schedule Start-Split in Y6
>                  */
>                 if (!(start_ss == 7 || last_ss < 6))
> -                       return -ERANGE;
> -
> -               for (i = 0; i < sch_ep->cs_count; i++)
> -                       if (test_bit(offset + i, tt->split_bit_map))
> -                               return -ERANGE;
> +                       return SCH_ERR_Y6;
>
> +               for (i = 0; i < sch_ep->cs_count; i++) {
> +                       if (test_bit(offset + i, tt->ss_bit_map))
> +                               return SCH_SS_OVERLAP;
> +               }
>         } else {
>                 u32 cs_count = DIV_ROUND_UP(sch_ep->maxpkt, FS_PAYLOAD_MAX);
>
> @@ -413,27 +494,36 @@ static int check_sch_tt(struct usb_device *udev,
>                  * must never schedule Start-Split in Y6
>                  */
>                 if (start_ss == 6)
> -                       return -ERANGE;
> +                       return SCH_ERR_Y6;
>
>                 /* one uframe for ss + one uframe for idle */
>                 start_cs = (start_ss + 2) % 8;
>                 last_cs = start_cs + cs_count - 1;
>
>                 if (last_cs > 7)
> -                       return -ERANGE;
> +                       return SCH_CS_OVERFLOW;
>
> +               /*
> +                * usb_20 spec section11.18, the bottom of page 378:
> +                * For interrupt endpoints, the maximum size of the LS/FS
> +                * transaction guarantees that it can never require more than
> +                * two complete-split transactions.
> +                */
>                 if (sch_ep->ep_type == ISOC_IN_EP)
>                         extra_cs_count = (last_cs == 7) ? 1 : 2;
>                 else /*  ep_type : INTR IN / INTR OUT */
> -                       extra_cs_count = (fs_budget_start == 6) ? 1 : 2;
> +                       extra_cs_count = 1;
>
>                 cs_count += extra_cs_count;
>                 if (cs_count > 7)
>                         cs_count = 7; /* HW limit */
>
> -               for (i = 0; i < cs_count + 2; i++) {
> -                       if (test_bit(offset + i, tt->split_bit_map))
> -                               return -ERANGE;
> +               if (test_bit(offset, tt->ss_bit_map))
> +                       return SCH_SS_OVERLAP;
> +
> +               if (sch_ep->ep_type == INT_OUT_EP) {
> +                       if (test_bit(offset, tt->idle_bit_map))
> +                               return SCH_FIXME;
>                 }
>
>                 sch_ep->cs_count = cs_count;
> @@ -448,41 +538,88 @@ static int check_sch_tt(struct usb_device *udev,
>                         sch_ep->num_budget_microframes = sch_ep->esit;
>         }
>
> -       return 0;
> +       return check_fs_bus_bw(sch_ep, offset);
>  }
>
> -static void update_sch_tt(struct usb_device *udev,
> -       struct mu3h_sch_ep_info *sch_ep)
> +static void update_sch_tt(struct mu3h_sch_ep_info *sch_ep, bool used)
>  {
>         struct mu3h_sch_tt *tt = sch_ep->sch_tt;
>         u32 base, num_esit;
> -       int i, j;
> +       u32 i, j;
>
>         num_esit = XHCI_MTK_MAX_ESIT / sch_ep->esit;
> +
>         for (i = 0; i < num_esit; i++) {
>                 base = sch_ep->offset + i * sch_ep->esit;
> -               for (j = 0; j < sch_ep->num_budget_microframes; j++)
> -                       set_bit(base + j, tt->split_bit_map);
> +
> +               if (sch_ep->ep_type == ISOC_OUT_EP) {
> +                       for (j = 0; j < sch_ep->num_budget_microframes; j++) {
> +                               if (used) {
> +                                       set_bit(base + j, tt->ss_bit_map);
> +                                       tt->fs_bus_bw[base + 1 + j] +=
> +                                               sch_ep->bw_cost_per_microframe;
> +                               } else {
> +                                       clear_bit(base + j, tt->ss_bit_map);
> +                                       tt->fs_bus_bw[base + 1 + j] -=
> +                                               sch_ep->bw_cost_per_microframe;
> +                               }
> +                       }
> +               } else {
> +                       if (used)
> +                               set_bit(base, tt->ss_bit_map);
> +                       else
> +                               clear_bit(base, tt->ss_bit_map);
> +
> +                       if (sch_ep->ep_type == INT_OUT_EP) {
> +                               if (used)
> +                                       set_bit(base + 1, tt->idle_bit_map);
> +                               else
> +                                       clear_bit(base + 1, tt->idle_bit_map);
> +                       }
> +
> +                       for (j = 0; j < sch_ep->cs_count; j++) {
> +                               if (used)
> +                                       tt->fs_bus_bw[base + 1 + j] +=
> +                                               sch_ep->bw_cost_per_microframe;
> +                               else
> +                                       tt->fs_bus_bw[base + 1 + j] -=
> +                                               sch_ep->bw_cost_per_microframe;
> +                       }
> +               }
> +       }
> +}
> +
> +static int load_ep_bw(struct mu3h_sch_bw_info *sch_bw,
> +                     struct mu3h_sch_ep_info *sch_ep, bool loaded)
> +{
> +       struct mu3h_sch_tt *tt = sch_ep->sch_tt;
> +
> +       if (sch_ep->sch_tt) {
> +               update_sch_tt(sch_ep, loaded);
> +               if (loaded)
> +                       list_add_tail(&sch_ep->tt_endpoint, &tt->ep_list);
> +               else
> +                       list_del(&sch_ep->tt_endpoint);
>         }
>
> -       list_add_tail(&sch_ep->tt_endpoint, &tt->ep_list);
> +       /* update bus bandwidth info */
> +       update_bus_bw(sch_bw, sch_ep, loaded);
> +       sch_ep->allocated = loaded;
> +       return 0;
>  }
>
>  static int check_sch_bw(struct usb_device *udev,
>         struct mu3h_sch_bw_info *sch_bw, struct mu3h_sch_ep_info *sch_ep)
>  {
>         u32 offset;
> -       u32 esit;
>         u32 min_bw;
>         u32 min_index;
>         u32 worst_bw;
>         u32 bw_boundary;
> +       u32 boundary;
>         u32 min_num_budget;
>         u32 min_cs_count;
> -       bool tt_offset_ok = false;
> -       int ret;
> -
> -       esit = sch_ep->esit;
> +       int ret = 0;
>
>         /*
>          * Search through all possible schedule microframes.
> @@ -492,16 +629,20 @@ static int check_sch_bw(struct usb_device *udev,
>         min_index = 0;
>         min_cs_count = sch_ep->cs_count;
>         min_num_budget = sch_ep->num_budget_microframes;
> -       for (offset = 0; offset < esit; offset++) {
> -               if (is_fs_or_ls(udev->speed)) {
> -                       ret = check_sch_tt(udev, sch_ep, offset);
> -                       if (ret)
> +
> +       if (is_fs_or_ls(udev->speed) && sch_ep->ep_type != ISOC_OUT_EP)
> +               boundary = sch_ep->esit + 1;
> +       else
> +               boundary = sch_ep->esit;
> +
> +       for (offset = 0; offset < sch_ep->esit; offset++) {
> +               if (sch_ep->sch_tt) {
> +                       ret = check_sch_tt(sch_ep, offset);
> +                       if (ret != SCH_SUCCESS)
>                                 continue;
> -                       else
> -                               tt_offset_ok = true;
>                 }
>
> -               if ((offset + sch_ep->num_budget_microframes) > sch_ep->esit)
> +               if ((offset + sch_ep->num_budget_microframes) > boundary)
>                         break;
>
>                 worst_bw = get_max_bw(sch_bw, sch_ep, offset);
> @@ -515,33 +656,22 @@ static int check_sch_bw(struct usb_device *udev,
>                         break;
>         }
>
> -       if (udev->speed == USB_SPEED_SUPER_PLUS)
> -               bw_boundary = SSP_BW_BOUNDARY;
> -       else if (udev->speed == USB_SPEED_SUPER)
> -               bw_boundary = SS_BW_BOUNDARY;
> -       else
> -               bw_boundary = HS_BW_BOUNDARY;
> -
> +       bw_boundary = get_bw_boundary(udev->speed);
>         /* check bandwidth */
> -       if (min_bw > bw_boundary)
> +       if (min_bw > bw_boundary) {
> +               if (ret) {
> +                       dev_err(&udev->dev, "%s %s\n", __func__,
> +                               sch_error_string(ret));
> +                       return -ret;
> +               }
> +
>                 return -ERANGE;
> +       }
>
>         sch_ep->offset = min_index;
>         sch_ep->cs_count = min_cs_count;
>         sch_ep->num_budget_microframes = min_num_budget;
> -
> -       if (is_fs_or_ls(udev->speed)) {
> -               /* all offset for tt is not ok*/
> -               if (!tt_offset_ok)
> -                       return -ERANGE;
> -
> -               update_sch_tt(udev, sch_ep);
> -       }
> -
> -       /* update bus bandwidth info */
> -       update_bus_bw(sch_bw, sch_ep, 1);
> -
> -       return 0;
> +       return load_ep_bw(sch_bw, sch_ep, true);
>  }
>
>  static void destroy_sch_ep(struct usb_device *udev,
> @@ -549,23 +679,17 @@ static void destroy_sch_ep(struct usb_device *udev,
>  {
>         /* only release ep bw check passed by check_sch_bw() */
>         if (sch_ep->allocated)
> -               update_bus_bw(sch_bw, sch_ep, 0);
> +               load_ep_bw(sch_bw, sch_ep, false);
>
> -       list_del(&sch_ep->endpoint);
> -
> -       if (sch_ep->sch_tt) {
> -               list_del(&sch_ep->tt_endpoint);
> -               drop_tt(udev);
> -       }
> -       kfree(sch_ep);
> +       delete_sch_ep(udev, sch_ep);
>  }
>
>  static bool need_bw_sch(struct usb_host_endpoint *ep,
>         enum usb_device_speed speed, int has_tt)
>  {
>         /* only for periodic endpoints */
> -       if (usb_endpoint_xfer_control(&ep->desc)
> -               || usb_endpoint_xfer_bulk(&ep->desc))
> +       if (usb_endpoint_xfer_control(&ep->desc) ||
> +           usb_endpoint_xfer_bulk(&ep->desc))
>                 return false;
>
>         /*
> diff --git a/drivers/usb/host/xhci-mtk.h b/drivers/usb/host/xhci-mtk.h
> index cbb09dfea62e..81e9b56958c5 100644
> --- a/drivers/usb/host/xhci-mtk.h
> +++ b/drivers/usb/host/xhci-mtk.h
> @@ -26,10 +26,10 @@
>   * @tt_port: TT port number
>   */
>  struct mu3h_sch_tt {
> -       DECLARE_BITMAP(split_bit_map, XHCI_MTK_MAX_ESIT);
> +       DECLARE_BITMAP(ss_bit_map, XHCI_MTK_MAX_ESIT);
> +       DECLARE_BITMAP(idle_bit_map, XHCI_MTK_MAX_ESIT);
> +       u32 fs_bus_bw[XHCI_MTK_MAX_ESIT + 1];
>         struct list_head ep_list;
> -       struct usb_tt *usb_tt;
> -       int tt_port;
>  };
>
>  /**
> @@ -84,9 +84,9 @@ struct mu3h_sch_ep_info {
>         struct list_head endpoint;
>         struct list_head tt_endpoint;
>         struct mu3h_sch_tt *sch_tt;
> +       struct usb_host_endpoint *ep;
>         u32 ep_type;
>         u32 maxpkt;
> -       void *ep;
>         bool allocated;
>         /*
>          * mtk xHCI scheduling information put into reserved DWs
> --
> 2.18.0