linux-kernel - Re: [PATCH v1] sdhci: tegra: Add workaround for Broadcom WiFi

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Message-ID: <CAPDyKFpWO_McZEoefX1T=SE=RYm_GU3S+LgYZrgJY_SJgv7egA@mail.gmail.com>
Date:   Wed, 11 Dec 2019 17:10:07 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        linux-tegra <linux-tegra@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1] sdhci: tegra: Add workaround for Broadcom WiFi

On Wed, 11 Dec 2019 at 16:46, Dmitry Osipenko <digetx@...il.com> wrote:
>
> Hello Ulf,
>
> 11.12.2019 11:11, Ulf Hansson пишет:
> > On Tue, 10 Dec 2019 at 02:40, Dmitry Osipenko <digetx@...il.com> wrote:
> >>
> >> All Tegra20 boards that have embedded Broadcom WiFi SDIO chip are affected
> >> by a problem where WiFi chip reports CCCR v1.10, while it should v1.20.
> >> In a result high-speed mode isn't enabled for the WiFi card and this
> >> results in a malfunctioning SDIO communication.
> >
> > Does that also mean SDIO_SPEED_SHS bit is set when reading SDIO_CCCR_SPEED?
>
> Yes, the SDIO_SPEED_SHS bit is set.
>
> >>  brcmfmac: brcmf_sdio_readframes: read 304 bytes from channel 1 failed: -84
> >>  brcmfmac: brcmf_sdio_rxfail: abort command, terminate frame, send NAK
> >>
> >> Downstream kernels are overriding card's CCCR info in SDHCI driver to fix
> >> the problem, let's do the same in upstream.
> >>
> >> The change is inspired by omap_hsmmc_init_card() of OMAP's HSMMC driver,
> >> which overrides card's info for the TI wl1251 WiFi.
> >
> > This is a temporary solution and should be replaced by doing the DT
> > parsing during
> >
> > So, yes, let's see if we can use a card quirk instead. That's the first option.
> >
> > A second option is simply to parse the DT subnode for a new DT
> > property during mmc_sdio_init_card(). Along the lines of what we do
> > for the broken-hpi DT binding for eMMC.
>
> Let's try the first option. My understanding is that the problem affects
> only the specific model of the WiFi chip and it's not a board-specific
> problem. I'll add Broadcom driver people to CC for the next version of
> the patch, maybe they'll have something to say.

Okay, sounds reasonable. By looking at your latest attempt for a fix,
I have two minor nitpicks, otherwise it looks good.

The nitpicks:
I suggest to rename MMC_QUIRK_HIGH_SPEED_CARD to MMC_QUIRK_HIGH_SPEED
and mmc_card_need_high_speed_toggle() to mmc_card_quirk_hs().

Kind regards
Uffe