linux-kernel - Re: [PATCH 1/2] spi: rockchip: add support for "cs-gpios" dts property

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Date:   Mon, 12 Jun 2017 10:18:06 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Shawn Lin <shawn.lin@...k-chips.com>
Cc:     Jeffy Chen <jeffy.chen@...k-chips.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Mark Brown <broonie@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Brian Norris <briannorris@...omium.org>,
        Heiko Stuebner <heiko@...ech.de>,
        Doug Anderson <dianders@...omium.org>,
        linux-spi <linux-spi@...r.kernel.org>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        Rob Herring <robh+dt@...nel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 1/2] spi: rockchip: add support for "cs-gpios" dts property

On Mon, Jun 12, 2017 at 9:15 AM, Shawn Lin <shawn.lin@...k-chips.com> wrote:
> On 2017/6/12 14:14, Jeffy Chen wrote:
>>
>> Support using "cs-gpios" property to specify cs gpios.
>>
>> Signed-off-by: Jeffy Chen <jeffy.chen@...k-chips.com>

>> index 83da493..02171b2 100644
>> --- a/Documentation/devicetree/bindings/spi/spi-rockchip.txt
>> +++ b/Documentation/devicetree/bindings/spi/spi-rockchip.txt
>> @@ -17,6 +17,7 @@ Required Properties:
>>          region.
>>   - interrupts: The interrupt number to the cpu. The interrupt specifier
>> format
>>                 depends on the interrupt controller.
>> +- cs-gpios : Specifies the gpio pins to be used for chipselects.
>
> It's not a required property, otherwise how other boards work as your
> patch 2 only add this for rk3399-gru.

>> --- a/drivers/spi/spi-rockchip.c
>> +++ b/drivers/spi/spi-rockchip.c

>> @@ -297,6 +302,50 @@ static void rockchip_spi_set_cs(struct spi_device
>> *spi, bool enable)
>>         pm_runtime_put_sync(rs->dev);
>>   }
>>   +static int rockchip_spi_setup(struct spi_device *spi)
>> +{
>> +       int ret = 0;
>> +       unsigned long flags = (spi->mode & SPI_CS_HIGH) ?
>> +                             GPIOF_OUT_INIT_LOW : GPIOF_OUT_INIT_HIGH;
>> +       struct rockchip_spi_data *data = spi_get_ctldata(spi);
>> +
>> +       if (!gpio_is_valid(spi->cs_gpio))
>> +               return 0;

> return -EINVAL?

Isn't this check meant to fall back to hardware CS if no cs-gpios property
is present?

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds