linux-kernel - Re: [PATCH v4 5/6] spi: at91-usart: add driver for at91-usart as spi

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Date:   Tue, 29 May 2018 16:34:37 +0200
From:   Nicolas Ferre <nicolas.ferre@...rochip.com>
To:     Radu Pirea <radu.pirea@...rochip.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>
CC:     Mark Brown <broonie@...nel.org>, <alexandre.belloni@...tlin.com>,
        Lee Jones <lee.jones@...aro.org>,
        Richard Genoud <richard.genoud@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-spi <linux-spi@...r.kernel.org>,
        linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        "open list:SERIAL DRIVERS" <linux-serial@...r.kernel.org>,
        Ludovic Desroches <ludovic.desroches@...rochip.com>
Subject: Re: [PATCH v4 5/6] spi: at91-usart: add driver for at91-usart as spi

On 29/05/2018 at 16:28, Radu Pirea wrote:
> 
> 
> On 05/28/2018 11:21 AM, Andy Shevchenko wrote:
>> On Fri, May 25, 2018 at 8:19 PM, Radu Pirea <radu.pirea@...rochip.com> wrote:
>>> This is the driver for at91-usart in spi mode. The USART IP can be configured
>>> to work in many modes and one of them is SPI.

[..]

>>> +static int at91_usart_gpio_setup(struct platform_device *pdev)
>>> +{
>>
>>> +       struct device_node      *np = pdev->dev.parent->of_node;
>>
>> Your driver is not OF specific as far as I can see. Drop all these
>> device_node stuff and change API calls respectively.
> 
> Ok. What do you suggest to use instead of OF API to get the count of
> cs-gpios and to read their values one by one?

As Alexandre said, we can make this driver OF specific.

What could be interesting is to use the gpio descriptors API and not the 
older one. This would allow us to have far more control over the gpio 
that we use in our drivers (Ludovic is converting our drivers to only 
use gpiod structures).

Regards,
   Nicolas

> 
>>
>>> +       int                     i;
>>
>>> +       int                     ret = 0;
>>> +       int                     nb = 0;
>>
>> What happened to indentation?
>>
>> Redundnant assignment for both.
>>
>>> +       if (!np)
>>> +               return -EINVAL;
>>> +
>>> +       nb = of_gpio_named_count(np, "cs-gpios");
>>> +       for (i = 0; i < nb; i++) {
>>> +               int cs_gpio = of_get_named_gpio(np, "cs-gpios", i);
>>> +
>>> +               if (cs_gpio < 0)
>>> +                       return cs_gpio;
>>> +
>>> +               if (gpio_is_valid(cs_gpio)) {
>>> +                       ret = devm_gpio_request_one(&pdev->dev, cs_gpio,
>>> +                                                   GPIOF_DIR_OUT,
>>> +                                                   dev_name(&pdev->dev));
>>> +                       if (ret)
>>> +                               return ret;
>>> +               }
>>> +       }
>>> +
>>> +       return 0;
>>> +}
[..]

-- 
Nicolas Ferre