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From:   Tomasz Figa <tfiga@chromium.org>
Date:   Thu, 7 Nov 2019 13:26:46 +0900
Message-ID: <CAAFQd5AiFZGZkND++umeTg5SoQK_VES5JEXdJ8hCGL-izs3NkQ@mail.gmail.com>
Subject: Re: [PATCH] usb: mtk-xhci: Set the XHCI_NO_64BIT_SUPPORT quirk
To:     Chunfeng Yun <chunfeng.yun@mediatek.com>
Cc:     Matthias Brugger <matthias.bgg@gmail.com>,
        linux-usb@vger.kernel.org, Mathias Nyman <mathias.nyman@intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-arm-kernel@lists.infradead.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@lists.infradead.org>,
        open list <linux-kernel@vger.kernel.org>,
        Changqi Hu <Changqi.Hu@mediatek.com>,
        Nicolas Boichat <drinkcat@chromium.org>,
        Shik Chen <shik@chromium.org>
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On Wed, Oct 30, 2019 at 5:15 PM Chunfeng Yun <chunfeng.yun@mediatek.com> wrote:
>
> Hi Tomasz,
>
> On Fri, 2019-10-11 at 13:35 +0900, Tomasz Figa wrote:
> > On Thu, Oct 10, 2019 at 7:59 PM Chunfeng Yun <chunfeng.yun@mediatek.com> wrote:
> > >
> > > On Thu, 2019-10-10 at 18:00 +0900, Tomasz Figa wrote:
> > > > Hi Chunfeng,
> > > >
> > > > On Thu, Oct 10, 2019 at 5:45 PM Chunfeng Yun <chunfeng.yun@mediatek.com> wrote:
> > > > >
> > > > > Hi, Tomasz,
> > > > >
> > > > > On Thu, 2019-10-10 at 16:50 +0900, Tomasz Figa wrote:
> > > > > > MediaTek XHCI host controller does not support 64-bit addressing despite
> > > > > > the AC64 bit of HCCPARAMS1 register being set. The platform-specific
> > > > > > glue sets the DMA mask to 32 bits on its own, but it has no effect,
> > > > > > because xhci_gen_setup() overrides it according to hardware
> > > > > > capabilities.
> > > Yes, this is what I want to do, maybe need remove DMA mask setting in
> > > platform-specific.
> > >
> > > > > >
> > > > > > Use the XHCI_NO_64BIT_SUPPORT quirk to tell the XHCI core to force
> > > > > > 32-bit DMA mask instead.
> > > > > >
> > > > > > Signed-off-by: Tomasz Figa <tfiga@chromium.org>
> > > > > > ---
> > > > > >  drivers/usb/host/xhci-mtk.c | 10 +++++-----
> > > > > >  1 file changed, 5 insertions(+), 5 deletions(-)
> > > > > >
> > > > > > diff --git a/drivers/usb/host/xhci-mtk.c b/drivers/usb/host/xhci-mtk.c
> > > > > > index b18a6baef204a..4d101d52cc11b 100644
> > > > > > --- a/drivers/usb/host/xhci-mtk.c
> > > > > > +++ b/drivers/usb/host/xhci-mtk.c
> > > > > > @@ -395,6 +395,11 @@ static void xhci_mtk_quirks(struct device *dev, struct xhci_hcd *xhci)
> > > > > >       xhci->quirks |= XHCI_SPURIOUS_SUCCESS;
> > > > > >       if (mtk->lpm_support)
> > > > > >               xhci->quirks |= XHCI_LPM_SUPPORT;
> > > > > > +     /*
> > > > > > +      * MTK host controller does not support 64-bit addressing, despite
> > > > > > +      * having the AC64 bit of the HCCPARAMS1 register set.
> > > > > > +      */
> > > > > > +     xhci->quirks |= XHCI_NO_64BIT_SUPPORT;
> > > > > Somes SoCs support 64bits in fact, so can't support this quirk, do you
> > > > > encounter any issues without this quirk?
> > > > >
> > > >
> > > > Thanks for taking a look at this patch.
> > > >
> > > > Yes, on MT8183 the DMA mask ended up being set to 64 bits, but
> > > > according to the information I received from MediaTek, the controller
> > > > on that SoC only supports 32 bits.
> > > As I know, mt8183 doesn't support memory greater than 4G mode.
> > >
> >
> > We have 4GB of DRAM at 0x40000000-0x140000000 on our board with
> > MT8183. What happens if you attempt to use the memory from
> > 0x100000000-0x140000000 with the XHCI controller on this SoC?
>
> Sorry for the late reply.
>
> I've checked it with USB DE, USB IP supports 64bit on MT8183, so no need
> set XHCI_NO_64BIT_SUPPORT.
> Would you please help to send a new patch to remove local dma mask
> setting, no need set it.
>
> Thanks a lot
>

Thanks Chunfeng. Sounds good then. I'll send a follow-up clean-up
patch once I catch up after a conference and vacation. :)

Best regards,
Tomasz

>
> >
> > > >
> > > > If some SoCs support only 32 bits and some support 64 bits, we may
> > > > either need to use different DT compatible string for them or add a DT
> > > > property and set the quirk based on that. Right now in upstream we
> > > > have:
> > > >
> > > > 1) "mediatek,mt8173-xhci", used by:
> > > > MT8173
> > > >
> > > > 2)"mediatek,mtk-xhci", used by:
> > > > MT2712
> > > > MT7622
> > > > MT8183 (not yet upstream, but I suppose it's on the mailing lists)
> > > >
> > > > Would you be able to check which of the SoCs above report 64 bits but
> > > > support only 32? (and so would need this quirk)
> > > I'm afraid I can't, almost all MTK SoCs supporting xHCI are using this
> > > driver, AC64 should be set rightly according to addressing capability.
> > >
> >
> > Does it mean that only MT8183 may be the only SoC with a problem with
> > this capability bit?
> >
> > Matthias, do you have access to MT2712 and MT7622 devices? I have
> > MT8173 and MT8183, so I can check them, but would be good to check
> > this on the other ones too.
>
>
> >
> > Best regards,
> > Tomasz
>
>