linux-kernel - Re: [PATCH v3 5/6] spi: at91-usart: add driver for at91-usart as spi

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Message-ID: <0e6e71e2-f8ac-7889-0d81-8d8a4c15223d@microchip.com>
Date:   Thu, 24 May 2018 19:04:11 +0300
From:   Radu Pirea <radu.pirea@...rochip.com>
To:     Mark Brown <broonie@...nel.org>
CC:     Andy Shevchenko <andy.shevchenko@...il.com>,
        devicetree <devicetree@...r.kernel.org>,
        "open list:SERIAL DRIVERS" <linux-serial@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
        linux-spi <linux-spi@...r.kernel.org>,
        Mark Rutland <mark.rutland@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Lee Jones <lee.jones@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>,
        Richard Genoud <richard.genoud@...il.com>,
        <alexandre.belloni@...tlin.com>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>
Subject: Re: [PATCH v3 5/6] spi: at91-usart: add driver for at91-usart as spi



On 05/17/2018 07:54 AM, Mark Brown wrote:
> On Tue, May 15, 2018 at 12:22:24PM +0300, Radu Pirea wrote:
>> On Mon, 2018-05-14 at 20:38 +0300, Andy Shevchenko wrote:
> 
>>> So, what is not going as expected in "SPI core takes care of CSs"
>>> case?
>>> Did you use oscilloscope for that?
> 
>> Yes, I used and CSs was not asserted. Anyway, I will will try again.
> 
> If the core chip select handling is not working properly for some reason
> then the core chip select handling should be fixed rather than just open
> coding in your driver - probably it's also broken for other users.
> 

Hi Mark,

I found the fix for cs-gpios. If I change spi_add_device function like 
this(see below) everything is ok.

int spi_add_device(struct spi_device *spi)

...

     if (ctlr->cs_gpios){
         spi->cs_gpio = ctlr->cs_gpios[spi->chip_select];
         if(gpio_is_valid(spi->cs_gpio))
             gpio_direction_output(spi->cs_gpio, !(spi->mode & 
SPI_CS_HIGH));

     }

...

     return status;
}

In the subsystem gpio direction of pins is never set and 
gpio_set_value() don't set the direction.
In my opinion gpio_direction_output() set direction should be called in 
spi_add_device. What do you think? Is ok?