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

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Message-ID: <28045442-6a1c-1e0b-0dfe-c36fa9de149a@gmail.com>
Date:   Wed, 11 Dec 2019 18:46:34 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Ulf Hansson <ulf.hansson@...aro.org>
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

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.

[snip]