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

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Message-ID: <70d88e65-5dd1-f218-dc39-e553a1b6acb5@web.de>
Date:   Sun, 9 Jul 2017 12:30:40 +0200
From:   Jan Kiszka <jan.kiszka@....de>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Daniel Mack <daniel@...que.org>,
        Haojian Zhuang <haojian.zhuang@...il.com>,
        Robert Jarzmik <robert.jarzmik@...e.fr>,
        Mark Brown <broonie@...nel.org>,
        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 2017-07-09 11:55, Andy Shevchenko wrote:
> On Sun, Jul 9, 2017 at 12:30 PM, Jan Kiszka <jan.kiszka@....de> wrote:
>> On 2017-07-08 23:48, Andy Shevchenko wrote:
>>> On Sat, Jul 8, 2017 at 11:41 AM, Jan Kiszka <jan.kiszka@....de> wrote:
>>>> From: Jan Kiszka <jan.kiszka@...mens.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.
>>>
>>> Can we first switch the driver to use GPIO descriptors instead of
>>> plain integers?
>>
>> -ENOPARSE
> 
> In code you are trying to modify there is a mix of plain integers and
> GPIO descriptors (and two APIs).
> Can we just convert it to use GPIO descriptors API?

That wasn't helpful either for someone not doing gpio development the
whole day. I suppose you wanted to suggest the conversion of
chip_data::chip_cs to struct gpio_desc * and the consistent usage of
gpiod_*, instead of gpio_*. That's not necessarily a precondition, but
it's a reasonable cleanup.

Jan



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