Re: [PATCH next v2 3/6] usb: xhci-mtk: update fs bus bandwidth by bw_budget_table

On Fri, Aug 27, 2021 at 2:49 PM Chunfeng Yun (云春峰)
[off-list ref] wrote:

On Thu, 2021-08-26 at 19:54 +0800, Ikjoon Jang wrote:

quoted

Hi Chunfeng,

On Thu, Aug 26, 2021 at 10:52 AM Chunfeng Yun <
chunfeng.yun@mediatek.com> wrote:

quoted

Use @bw_budget_table[] to update fs bus bandwidth due to
not all microframes consume @bw_cost_per_microframe, see
setup_sch_info().

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
---
v2: new patch, move from another series
---
 drivers/usb/host/xhci-mtk-sch.c | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/drivers/usb/host/xhci-mtk-sch.c

b/drivers/usb/host/xhci-mtk-sch.c
index cffcaf4dfa9f..83abd28269ca 100644

--- a/drivers/usb/host/xhci-mtk-sch.c
+++ b/drivers/usb/host/xhci-mtk-sch.c

@@ -458,8 +458,8 @@ static int check_fs_bus_bw(struct

mu3h_sch_ep_info *sch_ep, int offset)
                 * 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++) {
-                       tmp = tt->fs_bus_bw[base + j] + sch_ep-

quoted

bw_cost_per_microframe;

+               for (j = 0; j < sch_ep->num_budget_microframes;
j++) {
+                       tmp = tt->fs_bus_bw[base + j] + sch_ep-

quoted

bw_budget_table[j];

I'm worrying about this case with two endpoints,
* EP1OUT: isochronous, maxpacket=192: bw_budget_table[] = { 188, 188,
0, ... }
* EP2IN: interrupt, maxpacket=64: bw_budget_table[] = { 0, 0, 64, 64,
... }
(Is this correct bw_budget_table contents for those eps?)

Yes, ep1out isoc use two uframe, ep2in intr use a extra cs;

quoted

I'm not sure if it's okay for those two endpoints to be allocated
on the same u-frame slot.
Can you please check if this is okay for xhci-mtk?

Already test it this afternoon, can transfer data rightly on our dvt
env.

quoted

(I feel like I already asked the same questions many times.)

Yes, as said before, prefer to use bw_budget_table[], if there is
issue, we can fix it by building this table.

So do you mean such an allocation shouldn't be a problem by IP design?

This patch starts to allow such an allocation (again).
But i remember my earlier tests showed that when those two eps
in the above example are allocated on the same u-frame slot,
xhci-mtk puts "SSPLIT for EP2" between
"SSPLIT-start and SSPLIT-end for EP1OUT transaction",
which is a spec violation. Hub will generate bit stuffing errors on the
full-speed bus.

Thanks

quoted

quoted

                        if (tmp > FS_PAYLOAD_MAX)
                                return -ESCH_BW_OVERFLOW;
                }

@@ -534,21 +534,18 @@ 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 bw_updated;
        int i, j;

        num_esit = XHCI_MTK_MAX_ESIT / sch_ep->esit;

-       if (used)
-               bw_updated = sch_ep->bw_cost_per_microframe;
-       else
-               bw_updated = -sch_ep->bw_cost_per_microframe;
-
        for (i = 0; i < num_esit; i++) {
                base = sch_ep->offset + i * sch_ep->esit;

-               for (j = 0; j < sch_ep->cs_count; j++)
-                       tt->fs_bus_bw[base + j] += bw_updated;
+               for (j = 0; j < sch_ep->num_budget_microframes;
j++)
+                       if (used)
+                               tt->fs_bus_bw[base + j] += sch_ep-

quoted

bw_budget_table[j];

+                       else
+                               tt->fs_bus_bw[base + j] -= sch_ep-

quoted

bw_budget_table[j];

        }

        if (used)
--
2.18.0