linux-kernel - Re: [PATCH] spi: spi-geni-qcom: Use the new method of gpio CS control

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Date:   Wed, 2 Dec 2020 14:18:20 -0800
From:   Alexandru M Stan <amstan@...omium.org>
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     Mark Brown <broonie@...nel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-arm-msm@...r.kernel.org, linux-spi@...r.kernel.org,
        Akash Asthana <akashast@...eaurora.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Douglas Anderson <dianders@...omium.org>
Subject: Re: [PATCH] spi: spi-geni-qcom: Use the new method of gpio CS control

On Wed, Dec 2, 2020 at 1:49 PM Stephen Boyd <swboyd@...omium.org> wrote:
>
> Let's set the 'use_gpio_descriptors' field so that we use the new way of
> requesting the CS GPIOs in the core. This allows us to avoid having to
> configure the CS pins in "output" mode with an 'output-enable' pinctrl
> setting.
>
> Cc: Akash Asthana <akashast@...eaurora.org>
> Cc: Bjorn Andersson <bjorn.andersson@...aro.org>
> Reviewed-by: Douglas Anderson <dianders@...omium.org>
> Acked-by: Alexandru M Stan <amstan@...omium.org>
I meant this as a joke in chat. It doesn't really mean anything in any capacity.

> Signed-off-by: Stephen Boyd <swboyd@...omium.org>
> ---
>  drivers/spi/spi-geni-qcom.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/spi/spi-geni-qcom.c b/drivers/spi/spi-geni-qcom.c
> index 25810a7eef10..c4c88984abc9 100644
> --- a/drivers/spi/spi-geni-qcom.c
> +++ b/drivers/spi/spi-geni-qcom.c
> @@ -636,6 +636,7 @@ static int spi_geni_probe(struct platform_device *pdev)
>         spi->auto_runtime_pm = true;
>         spi->handle_err = handle_fifo_timeout;
>         spi->set_cs = spi_geni_set_cs;
> +       spi->use_gpio_descriptors = true;
>
>         init_completion(&mas->cs_done);
>         init_completion(&mas->cancel_done);
>
> base-commit: b65054597872ce3aefbc6a666385eabdf9e288da
> --
> https://chromeos.dev
>

Unfortunately this patch makes my cros-ec (the main EC that used to
work even before my debugging) also fail to probe:
[    0.839533] cros-ec-spi spi6.0: EC failed to respond in time
[    1.040453] cros-ec-spi spi6.0: EC failed to respond in time
[    1.040852] cros-ec-spi spi6.0: Cannot identify the EC: error -110
[    1.040855] cros-ec-spi spi6.0: cannot register EC, fallback to spidev
[    1.040942] cros-ec-spi: probe of spi6.0 failed with error -110

I wasn't closely looking at this part closely when I was using my
other spi port with spidev, so this is why I haven't noticed it
before.
Doug suggests this might be a polarity issue. More scoping to be had.

On the other hand my gpioinfo output is better with this patch:
       line  86: "AP_SPI_FP_MISO" unused input active-high
       line  87: "AP_SPI_FP_MOSI" unused input active-high
       line  88: "AP_SPI_FP_CLK" unused input active-high
       line  89: "AP_SPI_FP_CS_L" "spi10 CS0" output active-low [used]

Previously they were:
       line  86: "AP_SPI_FP_MISO" unused input active-high
       line  87: "AP_SPI_FP_MOSI" unused input active-high
       line  88: "AP_SPI_FP_CLK" unused input active-high
       line  89: "AP_SPI_FP_CS_L" unused output active-high

But I'm still disappointed the rest of the pins (CLK MISO MOSI) are
still "unused", but I was told that's just an artifact of those pins
not being gpios (but remuxed to spi).

Alexandru Stan (amstan)