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

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

Hi Chunfeng,

On Fri, Jul 30, 2021 at 4:51 PM Chunfeng Yun [off-list ref] 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->bw_cost_per_microframe;
+               for (j = 0; j < sch_ep->num_budget_microframes; j++) {
+                       tmp = tt->fs_bus_bw[base + j] + sch_ep->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

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;

Thanks

quoted

        }

        if (used)

quoted

--
2.18.0