Re: [PATCH v3 3/6] drm/dp: Add macro to check max_downspread capability

From: Stephen Boyd
Date: Thu Oct 28 2021 - 02:31:31 EST


Quoting Sankeerth Billakanti (2021-10-27 18:54:45)
> Add a macro to check for the max_downspread capability in
> drm_dp_helper.
>
> Signed-off-by: Sankeerth Billakanti <quic_sbillaka@xxxxxxxxxxx>
> ---

Looks OK to me. One question below

Reviewed-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>

> include/drm/drm_dp_helper.h | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index afdf7f4..b39e7a0 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -1784,6 +1784,12 @@ drm_dp_tps3_supported(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
> }
>
> static inline bool
> +drm_dp_max_downspread(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
> +{
> + return dpcd[DP_MAX_DOWNSPREAD] & DP_MAX_DOWNSPREAD_0_5;

Does it need a dpcd[DP_DPCD_REV] >= 0x11 check? Reading the spec I think
the answer may be that we check for 1.1 and always return 1 if so just
to make sure devices don't break the spec and put a 0 here when they're
rev is >= v1.1?

> +}
> +
> +static inline bool
> drm_dp_tps4_supported(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
> {
> return dpcd[DP_DPCD_REV] >= 0x14 &&