linux-kernel - Re: [PATCH 3/3] mmc: tmio: support IP-builtin card detection logic

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Message-ID: <CAK7LNASd9nMr=HKwfFN5E35XT_THzGSJ9XLuUkyZ5wBtjvGnOQ@mail.gmail.com>
Date:   Mon, 20 Nov 2017 17:03:13 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     Wolfram Sang <wsa@...-dreams.de>
Cc:     Wolfram Sang <wsa+renesas@...g-engineering.com>,
        linux-mmc <linux-mmc@...r.kernel.org>,
        Simon Horman <simon.horman@...ronome.com>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>
Subject: Re: [PATCH 3/3] mmc: tmio: support IP-builtin card detection logic

2017-11-20 4:45 GMT+09:00 Wolfram Sang <wsa@...-dreams.de>:
> On Wed, Nov 08, 2017 at 07:17:00PM +0900, Masahiro Yamada wrote:
>> A card detect GPIO is set up only for platforms with "cd-gpios"
>> DT property or TMIO_MMC_USE_GPIO_CD flag.  However, the driver
>> core always uses mmc_gpio_get_cd, which just fails with -ENOSYS
>> if ctx->cd_gpio is unset.
>>
>> The bit 5 of the status register provides the current signal level
>> of the CD line.  Allow to use it if the GPIO is unused.
>
> I might be missing something: Why do we need to report something
> sensible in this case? The card insert/eject interrupts calling
> mmc_detect_change is not enough?
>

Not enough.

mmc_detect_change() just schedules mmc_rescan().

Without correct ->get_cd(), how can mmc_rescan()
know whether a card is inserted or not?




-- 
Best Regards
Masahiro Yamada