linux-kernel - Re: [RFC v4 2/6] mmc: core: allow to match the device tree to apply quirks

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Date:   Fri, 05 Nov 2021 15:27:44 +0100
From:   Jérôme Pouiller <jerome.pouiller@...abs.com>
To:     Ulf Hansson <ulf.hansson@...aro.org>,
        Avri Altman <avri.altman@....com>,
        Shawn Lin <shawn.lin@...k-chips.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Tony Lindgren <tony@...mide.com>,
        Bean Huo <beanhuo@...ron.com>,
        "H. Nikolaus Schaller" <hns@...delico.com>
Cc:     notasas@...il.com, linux-mmc@...r.kernel.org,
        linux-kernel@...r.kernel.org, letux-kernel@...nphoenux.org,
        kernel@...a-handheld.com
Subject: Re: [RFC v4 2/6] mmc: core: allow to match the device tree to apply quirks

On Friday 5 November 2021 10:05:47 CET H. Nikolaus Schaller wrote:
> From: Jérôme Pouiller <jerome.pouiller@...abs.com>
> 
> MMC subsystem provides a way to apply quirks when a device match some
> properties (VID, PID, etc...) Unfortunately, some SDIO devices does not
> comply with the SDIO specification and does not provide reliable VID/PID
> (eg. Silabs WF200).
> 
> So, the drivers for these devices rely on device tree to identify the
> device.
> 
> This patch allows the MMC to also rely on the device tree to apply a
> quirk.
> 
> Signed-off-by: Jérôme Pouiller <jerome.pouiller@...abs.com>

Thank you for to have taken care of that (Maybe, you would like to add a
"Co-developed-by:" tag).


> ---
>  drivers/mmc/core/card.h   |  3 +++
>  drivers/mmc/core/quirks.h | 17 +++++++++++++++++
>  2 files changed, 20 insertions(+)
> 
> diff --git a/drivers/mmc/core/card.h b/drivers/mmc/core/card.h
> index 7bd392d55cfa5..a3204c19861a4 100644
> --- a/drivers/mmc/core/card.h
> +++ b/drivers/mmc/core/card.h
> @@ -59,6 +59,9 @@ struct mmc_fixup {
>         /* for MMC cards */
>         unsigned int ext_csd_rev;
> 
> +       /* Match against functions declared in device tree */
> +       const char **of_compatible;
> +
>         void (*vendor_fixup)(struct mmc_card *card, int data);
>         int data;
>  };
> diff --git a/drivers/mmc/core/quirks.h b/drivers/mmc/core/quirks.h
> index c7ef2d14b359f..ee591fd8aeca2 100644
> --- a/drivers/mmc/core/quirks.h
> +++ b/drivers/mmc/core/quirks.h
> @@ -10,6 +10,7 @@
>   *
>   */
> 
> +#include <linux/of.h>
>  #include <linux/mmc/sdio_ids.h>
> 
>  #include "card.h"
> @@ -145,6 +146,19 @@ static const struct mmc_fixup __maybe_unused sdio_fixup_methods[] = {
>         END_FIXUP
>  };
> 
> +static inline bool mmc_fixup_of_compatible_match(struct mmc_card *card,
> +                                                const char *const *compat_list)
> +{
> +       struct device_node *np;
> +
> +       for_each_child_of_node(mmc_dev(card->host)->of_node, np) {
> +               if (of_device_compatible_match(np, compat_list))
> +                       return true;

Intel robot complains about of_device_compatible_match():

    ERROR: modpost: "of_device_compatible_match" [drivers/mmc/core/mmc_core.ko] undefined!

I think we have to add this line:

    EXPORT_SYMBOL(of_device_compatible_match);

in drivers/of/base.c

> +       }
> +
> +       return false;
> +}
> +
>  static inline void mmc_fixup_device(struct mmc_card *card,
>                                     const struct mmc_fixup *table)
>  {
> @@ -173,6 +187,9 @@ static inline void mmc_fixup_device(struct mmc_card *card,
>                         continue;
>                 if (rev < f->rev_start || rev > f->rev_end)
>                         continue;
> +               if (f->of_compatible &&
> +                   !mmc_fixup_of_compatible_match(card, f->of_compatible))
> +                       continue;
> 
>                 dev_dbg(&card->dev, "calling %ps\n", f->vendor_fixup);
>                 f->vendor_fixup(card, f->data);
> --
> 2.33.0
> 
> 

-- 
Jérôme Pouiller