From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Shevchenko Subject: Re: [PATCH] spi: pxa2xx: Only claim CS GPIOs when the slave device is created Date: Mon, 24 Jul 2017 14:14:48 +0300 Message-ID: References: <90b3e14d-0077-9a25-9d90-ab340577af57@web.de> <59066818-a284-4da0-d05f-d2503aeee44b@web.de> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Cc: Daniel Mack , Haojian Zhuang , Robert Jarzmik , Mark Brown , linux-spi , Linux Kernel Mailing List , linux-arm-kernel To: Jan Kiszka Return-path: In-Reply-To: Sender: linux-spi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: On Mon, Jul 24, 2017 at 2:06 PM, Jan Kiszka wrote: > On 2017-07-24 13:02, Andy Shevchenko wrote: >> On Mon, Jul 24, 2017 at 1:53 PM, Jan Kiszka wrote: >>> On 2017-07-24 12:44, Andy Shevchenko wrote: >>>> +Cc: Mika >>>> >>>> On Sat, Jul 8, 2017 at 11:41 AM, Jan Kiszka wrote: >>>>> From: Jan Kiszka >>>>> >>>>> 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. Nope, one. Since we are talking about recurrent call to gpiod_get_index() with the same index. -- With Best Regards, Andy Shevchenko -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html