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

From: Dmitry Osipenko
Date: Tue Dec 10 2019 - 09:16:04 EST

10.12.2019 15:52, Thierry Reding ÐÐÑÐÑ:
> On Tue, Dec 10, 2019 at 04:40:11AM +0300, Dmitry Osipenko 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.
>> 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.
>> Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
>> ---
>> drivers/mmc/host/sdhci-tegra.c | 28 ++++++++++++++++++++++++++++
>> 1 file changed, 28 insertions(+)
> This seems like the wrong place to do this. If this is specific to this
> WiFi SDIO chip this should be handled at the SDIO card or function
> level. It seems like the SDIO infrastructure doesn't currently allow
> this because the OF nodes are attached to the card after
> mmc_sdio_init_card(), whereas it seems like the quirk is already needed
> during mmc_sdio_init_card().
> That said, I think we could have some common code that's executed as
> part of mmc_attach_sdio() (and before mmc_sdio_init_card()).
> Actually, it looks like we already have something like that.
> mmc_sdio_init_card() calls mmc_fixup_device() with sdio_fixup_methods
> after doing some very basic initialization. Do you know if things start
> to go wrong before or after that point? It might be worth looking at
> that SDIO fixup array and add something that would override the CCCR
> support. That would fix things in a more generic way rather than
> requiring every host controller driver to duplicate this quirk.

Hello Thierry,

Thank you very much for the suggestion, looks like indeed it is possible
to make workaround in a generic way.

Ulf / Adrian, will something like this be acceptable:

diff --git a/drivers/mmc/core/card.h b/drivers/mmc/core/card.h
index 7bd392d55cfa..a6001f210b9e 100644
--- a/drivers/mmc/core/card.h
+++ b/drivers/mmc/core/card.h
@@ -150,6 +150,12 @@ static inline void __maybe_unused
add_limit_rate_quirk(struct mmc_card *card,
card->quirk_max_rate = data;

+static inline void __maybe_unused add_high_speed_quirk(struct mmc_card
+ int data)
+ card->cccr.high_speed = data;
* Quirk add/remove for MMC products.
diff --git a/drivers/mmc/core/quirks.h b/drivers/mmc/core/quirks.h
index 3dba15bccce2..a824c0caa7fb 100644
--- a/drivers/mmc/core/quirks.h
+++ b/drivers/mmc/core/quirks.h
@@ -142,6 +142,9 @@ static const struct mmc_fixup sdio_fixup_methods[] = {
add_limit_rate_quirk, 150000000),

+ add_high_speed_quirk, 1),