linux-kernel - Re: [PATCH 3/3] ARM: davinci: hawk: use gpio descriptor for card detect

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Message-ID: <CAKXjFTNfnEZ09XDRV8YvaD=f6OCz=iNk7R-=vN-BtBEcQzDXRw@mail.gmail.com>
Date:   Tue, 22 Nov 2016 13:49:35 +0100
From:   Axel Haslam <ahaslam@...libre.com>
To:     Sekhar Nori <nsekhar@...com>
Cc:     Kevin Hilman <khilman@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] ARM: davinci: hawk: use gpio descriptor for card detect

On Tue, Nov 22, 2016 at 11:26 AM, Sekhar Nori <nsekhar@...com> wrote:
> On Monday 21 November 2016 09:45 PM, Axel Haslam wrote:
>> Currently the mmc driver is polling the gpio to know if the
>> card was removed.
>>
>> By using a gpio descriptor instead of the platform callbacks, the
>> driver will be able to register the gpio with the mmc core with API's
>> designed for this purpose.
>>
>> This has the advantage that an irq will be registered,
>> and polling is no longer needed. Also, platform callbacks can be removed.
>>
>> Signed-off-by: Axel Haslam <ahaslam@...libre.com>
>
> This patch looks good, provided it is not based of 1/3 and 2/3. There
> are other boards in mach-davinci using the card detect and wp callbacks.
> And some like board-dm365-evm.c have those pins routed through a CPLD.
> So I guess there is more work to be done before platform callbacks can
> completely be removed from MMC/SD driver. But the closer we get, the
> better it is :)
>

Yes, i saw the platform using CPLD for the pins. that might be tricky to remove.
we can flag the mmc "broken card detect" which would force polling on the pin.
im not sure if it is feasible to move the cpld pin handling to a
driver.. (maybe a
gpio driver?)


> Thanks,
> Sekhar
>