Re: [PATCH 08/11] usb: xhci-mtk: update fs bus bandwidth by bw_budget_table

On Wed, 2021-08-04 at 22:06 +0800, Ikjoon Jang wrote:

Hi,

On Wed, Aug 4, 2021 at 1:19 PM Chunfeng Yun <
chunfeng.yun@mediatek.com> wrote:

quoted

On Tue, 2021-08-03 at 14:05 +0800, Ikjoon Jang wrote:

quoted

Hi Chunfeng,

On Fri, Jul 30, 2021 at 4:51 PM 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>
---
 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 0bb1a6295d64..10c0f0f6461f 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];

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

I agree that xhci-mtk-sch still has more rooms for tt periodic
bandwidth
but I think this approach could trigger a problem.

See updat_bus_bw(), when add fs ep's bandwidth, it uses
bw_budget_table[], so prefer to use the same way

quoted

for example, if there are two endpoints scheduled in the same u-
frame index,
* ep1out  = iso 192bytes bw_budget_table[] = { 188, 188, 0, ...}
--> y0
* ep2in = int 64bytes, bw_budget_table[] = { 0, 0, 64, ... }  -->
y0

(If this is possible allocation from this patch),
I guess xhci-mtk could have some problems on internal scheduling?

Test it on dvt env. don't encounter issues;

As you can see In the above example, this patch starts to allow that
allocation.
Do you mean that we don't have to worry about such a case (on all MTK
platforms)?

No, that is another question, when update bus_bw[] and fs_bus_bw[] for
FS with TT should use the same bw_budget_table[] which is filled in
setup_sch_info(). If the bw_budget_table[] is something wrong, we can
prepare new patch to fix it.

thanks

quoted

Thanks

quoted

quoted

        }

        if (used)
--
2.18.0