[PATCH v3 2/9] usb: xhci: create one unified function to calculate TRB TD remainder.

Bin Meng bmeng.cn at gmail.com
Tue Sep 8 07:41:55 CEST 2020


On Mon, Sep 7, 2020 at 3:14 PM Chunfeng Yun <chunfeng.yun at mediatek.com> wrote:
>

nits: please remove the ending period in the commit title

> xhci versions 1.0 and later report the untransferred data remaining in a
> TD a bit differently than older hosts.
>
> We used to have separate functions for these, and needed to check host
> version before calling the right function.
>
> Now Mediatek host has an additional quirk on how it uses the TD Size
> field for remaining data. To prevent yet another function for calculating
> remainder we instead want to make one quirk friendly unified function.
>
> Porting from the Linux:
> c840d6ce772d("xhci: create one unified function to calculate TRB TD remainder.")
> 124c39371114("xhci: use boolean to indicate last trb in td remainder calculation")
>
> Signed-off-by: Chunfeng Yun <chunfeng.yun at mediatek.com>
> ---
> v2~v3: no changes
> ---
>  drivers/usb/host/xhci-ring.c | 105 +++++++++++++++++++++----------------------
>  include/usb/xhci.h           |   2 +
>  2 files changed, 52 insertions(+), 55 deletions(-)
>
> diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
> index 79bfc34..0f86b01 100644
> --- a/drivers/usb/host/xhci-ring.c
> +++ b/drivers/usb/host/xhci-ring.c
> @@ -298,55 +298,52 @@ void xhci_queue_command(struct xhci_ctrl *ctrl, u8 *ptr, u32 slot_id,
>         xhci_writel(&ctrl->dba->doorbell[0], DB_VALUE_HOST);
>  }
>
> -/**
> - * The TD size is the number of bytes remaining in the TD (including this TRB),
> - * right shifted by 10.
> - * It must fit in bits 21:17, so it can't be bigger than 31.
> +/*
> + * For xHCI 1.0 host controllers, TD size is the number of max packet sized
> + * packets remaining in the TD (*not* including this TRB).
>   *
> - * @param remainder    remaining packets to be sent
> - * @return remainder if remainder is less than max else max
> - */
> -static u32 xhci_td_remainder(unsigned int remainder)
> -{
> -       u32 max = (1 << (21 - 17 + 1)) - 1;
> -
> -       if ((remainder >> 10) >= max)
> -               return max << 17;
> -       else
> -               return (remainder >> 10) << 17;
> -}
> -
> -/**
> - * Finds out the remanining packets to be sent
> + * Total TD packet count = total_packet_count =
> + *     DIV_ROUND_UP(TD size in bytes / wMaxPacketSize)
> + *
> + * Packets transferred up to and including this TRB = packets_transferred =
> + *     rounddown(total bytes transferred including this TRB / wMaxPacketSize)
> + *
> + * TD size = total_packet_count - packets_transferred
>   *
> - * @param running_total        total size sent so far
> + * For xHCI 0.96 and older, TD size field should be the remaining bytes
> + * including this TRB, right shifted by 10
> + *
> + * For all hosts it must fit in bits 21:17, so it can't be bigger than 31.
> + * This is taken care of in the TRB_TD_SIZE() macro
> + *
> + * The last TRB in a TD must have the TD size set to zero.
> + *
> + * @param ctrl host controller data structure
> + * @param transferred  total size sent so far
>   * @param trb_buff_len length of the TRB Buffer
> - * @param total_packet_count   total packet count
> - * @param maxpacketsize                max packet size of current pipe
> - * @param num_trbs_left                number of TRBs left to be processed
> - * @return 0 if running_total or trb_buff_len is 0, else remainder
> + * @param td_total_len total packet count
> + * @param maxp max packet size of current pipe
> + * @param more_trbs_coming     indicate last trb in TD
> + * @return remainder
>   */
> -static u32 xhci_v1_0_td_remainder(int running_total,
> -                               int trb_buff_len,
> -                               unsigned int total_packet_count,
> -                               int maxpacketsize,
> -                               unsigned int num_trbs_left)
> +static u32 xhci_td_remainder(struct xhci_ctrl *ctrl, int transferred,
> +                            int trb_buff_len, unsigned int td_total_len,
> +                            int maxp, bool more_trbs_coming)
>  {
> -       int packets_transferred;
> +       u32 total_packet_count;
> +
> +       if (ctrl->hci_version < 0x100)
> +               return ((td_total_len - transferred) >> 10);
>
>         /* One TRB with a zero-length data packet. */
> -       if (num_trbs_left == 0 || (running_total == 0 && trb_buff_len == 0))
> +       if (!more_trbs_coming || (transferred == 0 && trb_buff_len == 0) ||
> +           trb_buff_len == td_total_len)
>                 return 0;
>
> -       /*
> -        * All the TRB queueing functions don't count the current TRB in
> -        * running_total.
> -        */
> -       packets_transferred = (running_total + trb_buff_len) / maxpacketsize;
> +       total_packet_count = DIV_ROUND_UP(td_total_len, maxp);
>
> -       if ((total_packet_count - packets_transferred) > 31)
> -               return 31 << 17;
> -       return (total_packet_count - packets_transferred) << 17;
> +       /* Queueing functions don't count the current TRB into transferred */
> +       return (total_packet_count - ((transferred + trb_buff_len) / maxp));
>  }
>
>  /**
> @@ -572,7 +569,7 @@ int xhci_bulk_tx(struct usb_device *udev, unsigned long pipe,
>         union xhci_trb *event;
>
>         int running_total, trb_buff_len;
> -       unsigned int total_packet_count;
> +       bool more_trbs_coming = true;
>         int maxpacketsize;
>         u64 addr;
>         int ret;
> @@ -636,8 +633,6 @@ int xhci_bulk_tx(struct usb_device *udev, unsigned long pipe,
>         running_total = 0;
>         maxpacketsize = usb_maxpacket(udev, pipe);
>
> -       total_packet_count = DIV_ROUND_UP(length, maxpacketsize);
> -
>         /* How much data is in the first TRB? */
>         /*
>          * How much data is (potentially) left before the 64KB boundary?
> @@ -672,27 +667,24 @@ int xhci_bulk_tx(struct usb_device *udev, unsigned long pipe,
>                  * Chain all the TRBs together; clear the chain bit in the last
>                  * TRB to indicate it's the last TRB in the chain.
>                  */
> -               if (num_trbs > 1)
> +               if (num_trbs > 1) {
>                         field |= TRB_CHAIN;
> -               else
> +               } else {
>                         field |= TRB_IOC;
> +                       more_trbs_coming = false;
> +               }
>
>                 /* Only set interrupt on short packet for IN endpoints */
>                 if (usb_pipein(pipe))
>                         field |= TRB_ISP;
>
>                 /* Set the TRB length, TD size, and interrupter fields. */
> -               if (ctrl->hci_version < 0x100)
> -                       remainder = xhci_td_remainder(length - running_total);
> -               else
> -                       remainder = xhci_v1_0_td_remainder(running_total,
> -                                                          trb_buff_len,
> -                                                          total_packet_count,
> -                                                          maxpacketsize,
> -                                                          num_trbs - 1);
> +               remainder = xhci_td_remainder(ctrl, running_total, trb_buff_len,
> +                                             length, maxpacketsize,
> +                                             more_trbs_coming);
>
>                 length_field = ((trb_buff_len & TRB_LEN_MASK) |
> -                               remainder |
> +                               TRB_TD_SIZE(remainder) |
>                                 ((0 & TRB_INTR_TARGET_MASK) <<
>                                 TRB_INTR_TARGET_SHIFT));
>
> @@ -764,6 +756,7 @@ int xhci_ctrl_tx(struct usb_device *udev, unsigned long pipe,
>         struct xhci_virt_device *virt_dev = ctrl->devs[slot_id];
>         struct xhci_ring *ep_ring;
>         union xhci_trb *event;
> +       u32 remainder;
>
>         debug("req=%u (%#x), type=%u (%#x), value=%u (%#x), index=%u\n",
>                 req->request, req->request,
> @@ -866,12 +859,14 @@ int xhci_ctrl_tx(struct usb_device *udev, unsigned long pipe,
>         else
>                 field = (TRB_DATA << TRB_TYPE_SHIFT);
>
> -       length_field = (length & TRB_LEN_MASK) | xhci_td_remainder(length) |
> +       remainder = xhci_td_remainder(ctrl, 0, length, length,
> +                                     usb_maxpacket(udev, pipe), 1);

1 should be true

> +       length_field = (length & TRB_LEN_MASK) | TRB_TD_SIZE(remainder) |
>                         ((0 & TRB_INTR_TARGET_MASK) << TRB_INTR_TARGET_SHIFT);
>         debug("length_field = %d, length = %d,"
>                 "xhci_td_remainder(length) = %d , TRB_INTR_TARGET(0) = %d\n",
>                 length_field, (length & TRB_LEN_MASK),
> -               xhci_td_remainder(length), 0);
> +               TRB_TD_SIZE(remainder), 0);
>
>         if (length > 0) {
>                 if (req->requesttype & USB_DIR_IN)
> diff --git a/include/usb/xhci.h b/include/usb/xhci.h
> index a3e5914..15926eb 100644
> --- a/include/usb/xhci.h
> +++ b/include/usb/xhci.h
> @@ -850,6 +850,8 @@ struct xhci_event_cmd {
>  /* transfer_len bitmasks - bits 0:16 */
>  #define        TRB_LEN(p)                      ((p) & 0x1ffff)
>  #define        TRB_LEN_MASK                    (0x1ffff)
> +/* TD Size, packets remaining in this TD, bits 21:17 (5 bits, so max 31) */
> +#define TRB_TD_SIZE(p)          (min((p), (u32)31) << 17)
>  /* Interrupter Target - which MSI-X vector to target the completion event at */
>  #define        TRB_INTR_TARGET_SHIFT           (22)
>  #define        TRB_INTR_TARGET_MASK            (0x3ff)

Otherwise,
Reviewed-by: Bin Meng <bmeng.cn at gmail.com>


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