linux-kernel - Re: [PATCH] spi: pxa2xx: Only claim CS GPIOs when the slave device is created

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Date:   Mon, 10 Jul 2017 19:31:24 +0200
From:   Jan Kiszka <jan.kiszka@....de>
To:     Mark Brown <broonie@...nel.org>,
        Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Daniel Mack <daniel@...que.org>,
        Haojian Zhuang <haojian.zhuang@...il.com>,
        Robert Jarzmik <robert.jarzmik@...e.fr>,
        linux-spi <linux-spi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] spi: pxa2xx: Only claim CS GPIOs when the slave device is
 created

On 2017-07-10 14:09, Mark Brown wrote:
> On Sun, Jul 09, 2017 at 12:48:10AM +0300, Andy Shevchenko wrote:
>> On Sat, Jul 8, 2017 at 11:41 AM, Jan Kiszka <jan.kiszka@....de> wrote:
> 
>>> Tested on the IOT2000 where the second SPI bus is connected to an
>>> Arduino-compatible connector and multiplexed between SPI, GPIO and PWM
>>> usage.
> 
>> Can we first switch the driver to use GPIO descriptors instead of
>> plain integers?
> 
> Only if you also convert the SPI core to use descriptors, Chris Packham
> was looking at that but he needed update the ep93xx drivers among others
> and getting reviewers was hard.
> 

IIUC, we can't convert completely due to some legacy boards providing
their CS lines as integers. But even then, a few more API usages can be
converted.

While looking into this, I noticed that this patch violated the formal
rule to never release a GPIO with the old API when it was requested with
the new one. That's at least stated in the docs, even though gpio_free
is equivalent to gpiod_put. Fixed that already, but I need to find some
time to retest.

Jan



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