Messages in this thread | | | Subject | Re: [PATCH] spi: pxa2xx: Only claim CS GPIOs when the slave device is created | From | Jan Kiszka <> | Date | Mon, 24 Jul 2017 13:06:43 +0200 |
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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
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