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

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Message-ID: <72ee7a203d8a49e6e43a954b45133470ee6d5c16.camel@mediatek.com>
Date:   Fri, 27 Aug 2021 06:49:27 +0000
From:   Chunfeng Yun (云春峰) 
        <Chunfeng.Yun@...iatek.com>
To:     "ikjn@...omium.org" <ikjn@...omium.org>
CC:     "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        Yaqii Wu (武亚奇) <Yaqii.Wu@...iatek.com>,
        "mathias.nyman@...el.com" <mathias.nyman@...el.com>,
        Eddie Hung (洪正鑫) 
        <Eddie.Hung@...iatek.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>
Subject: Re: [PATCH next v2 3/6] usb: xhci-mtk: update fs bus bandwidth by
 bw_budget_table

On Thu, 2021-08-26 at 19:54 +0800, Ikjoon Jang wrote:
> Hi Chunfeng,
> 
> On Thu, Aug 26, 2021 at 10:52 AM Chunfeng Yun <
> chunfeng.yun@...iatek.com> wrote:
> > 
> > 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@...iatek.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-
> > >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];
> 
> 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;
> 
> 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.

> (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.

Thanks
> 
> 
> >                         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];
> >         }
> > 
> >         if (used)
> > --
> > 2.18.0
> >