Re: [virtio-dev][PATCH V9 2/2] virtio-spi: add the device specification

[Cornelia Huck <cohuck@redhat.com>]

On Tue, Dec 12 2023, Haixu Cui <quic_haixcui@quicinc.com> wrote:

[BTW: A changelog would be useful, either in the patch or in the cover
letter.]

> The Virtio SPI (Serial Peripheral Interface) device is a virtual
> SPI controller that allows the driver to operate and use the SPI
> controller under the control of the host.
>
> This patch adds the specification for virtio-spi.
>
> Signed-off-by: Haixu Cui <quic_haixcui@quicinc.com>
> Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
>  device-types/spi/description.tex        | 281 ++++++++++++++++++++++++
>  device-types/spi/device-conformance.tex |   7 +
>  device-types/spi/driver-conformance.tex |   7 +
>  3 files changed, 295 insertions(+)
>  create mode 100644 device-types/spi/description.tex
>  create mode 100644 device-types/spi/device-conformance.tex
>  create mode 100644 device-types/spi/driver-conformance.tex
>
> diff --git a/device-types/spi/description.tex b/device-types/spi/description.tex

Please move inclusion of this new file into content.tex here, instead of
including a not-yet-existing file in the previous patch.

(...)

> +\field{mode_func_supported} indicates whether the following features are supported or not:
> +        bit 0-1: CPHA feature,
> +            0b00: invalid, must support as least one CPHA setting.
> +            0b01: supports CPHA=0 only;
> +            0b10: supports CPHA=1 only;
> +            0b11: supports CPHA=0 and CPHA=1;
> +
> +        bit 2-3: CPOL feature,
> +            0b00: invalid, must support as least one CPOL setting.
> +            0b01: supports CPOL=0 only;
> +            0b10: supports CPOL=1 only;
> +            0b11: supports CPOL=0 and CPOL=1;
> +
> +        bit 4: chipselect active high feature, 0 for unsupported and 1 for supported,
> +            chipselect active low must always be supported.
> +
> +        bit 5: LSB first feature, 0 for unsupported and 1 for supported, MSB first must always be
> +            supported.
> +
> +        bit 6: loopback mode feature, 0 for unsupported and 1 for supported, normal mode
> +            must always be supported.
> +
> +Note: CPOL is clock polarity and CPHA is clock phase. If CPOL is 0, the clock idles at the logical
> +low voltage, otherwise it idles at the logical high voltage. CPHA determines how data is outputted
> +and sampled.

Shouldn't you also specify what CPHA==0 and CPHA==1 mean?


(...)

> +VIRTIO_SPI_TRANS_ERR indicates a transfer error, which means that the parameters are all
> +valid but the trasnfer process failed.

s/trasnfer/transfer/

LGTM otherwise. Does anybody else have comments?