lkml.org 
[lkml]   [2017]   [Jul]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] spi: pxa2xx: Only claim CS GPIOs when the slave device is created
From
Date
On 2017-07-24 13:02, Andy Shevchenko wrote:
> On Mon, Jul 24, 2017 at 1:53 PM, Jan Kiszka <jan.kiszka@web.de> wrote:
>> On 2017-07-24 12:44, Andy Shevchenko wrote:
>>> +Cc: Mika
>>>
>>> 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.
>
>>> This breaks all systems which are using _DSD.
>>
>> Err, can you elaborate? Worked fine here with _DSD on the IOT2000.
>
> Sure, the setup() function can be called several times for the same
> chip (as written in the comment inside the function).
> Definitely your code doesn't follow this, since gpiod_get_index() is
> returning -EBUSY when called 2+ time, that's what I got on all my
> tests.

Ah, multiple devices on the same controller - I only had one.

>
>>> While I'm looking for fix, I get feeling that the approach itself is not right,
>>>
>>> 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.
>
> Please, send it as RFC, because it might have something we can use/re-use.
>

OK, will dig them out later.

Jan

[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2017-07-24 13:07    [W:0.065 / U:0.804 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site