Subject: Re: [PATCH] spi: pxa2xx: Only claim CS GPIOs when the slave device is
 created
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Daniel Mack <daniel@zonque.org>,
        Haojian Zhuang <haojian.zhuang@gmail.com>,
        Robert Jarzmik <robert.jarzmik@free.fr>,
        Mark Brown <broonie@kernel.org>, linux-spi <linux-spi@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
References: <90b3e14d-0077-9a25-9d90-ab340577af57@web.de>
 <CAHp75VfpJzOdhMyZoMGnC4CQc5kGxq1k-__dpmVAOaxaD04w6Q@mail.gmail.com>
From: Jan Kiszka <jan.kiszka@web.de>
Message-ID: <59066818-a284-4da0-d05f-d2503aeee44b@web.de>
Date: Mon, 24 Jul 2017 12:53:20 +0200
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From: Jan Kiszka <jan.kiszka@web.de>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Daniel Mack <daniel@zonque.org>, Haojian Zhuang
 <haojian.zhuang@gmail.com>, Robert Jarzmik <robert.jarzmik@free.fr>,
 Mark Brown <broonie@kernel.org>, linux-spi <linux-spi@vger.kernel.org>,
 Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
 linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Message-ID: <59066818-a284-4da0-d05f-d2503aeee44b@web.de>
Subject: Re: [PATCH] spi: pxa2xx: Only claim CS GPIOs when the slave device is
 created
References: <90b3e14d-0077-9a25-9d90-ab340577af57@web.de>
 <CAHp75VfpJzOdhMyZoMGnC4CQc5kGxq1k-__dpmVAOaxaD04w6Q@mail.gmail.com>
In-Reply-To: <CAHp75VfpJzOdhMyZoMGnC4CQc5kGxq1k-__dpmVAOaxaD04w6Q@mail.gmail.com>

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On 2017-07-24 12:44, Andy Shevchenko wrote:
> +Cc: Mika
>=20
> On Sat, Jul 8, 2017 at 11:41 AM, Jan Kiszka <jan.kiszka@web.de> wrote:
>> From: Jan Kiszka <jan.kiszka@siemens.com>
>>
>> Avoid hogging chip select GPIOs just because they are listed for the
>> master. They might be mulitplexed and, if no slave device is attached,=

>> used for different purposes. Moreover, this strategy avoids having to
>> allocate a cs_gpiods structure.
>>
>> Tested on the IOT2000 where the second SPI bus is connected to an
>> Arduino-compatible connector and multiplexed between SPI, GPIO and PWM=

>> usage.
>>
>=20
> This breaks all systems which are using _DSD.

Err, can you elaborate? Worked fine here with _DSD on the IOT2000.

>=20
> While I'm looking for fix, I get feeling that the approach itself is no=
t right,
>=20
> So, for now I would vote for immediate revert and then rethink what we
> can do here.

I'm fine with reverting because the patch wasn't clean anyway (mixed old
and new GPIO API) - aside from whatever you found in addition. I had an
update pending but, as you are looking into this anyway, I'm sure your
patches will be more holistic.

Thanks,
Jan


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