Re: [PATCH v2 4/5] drm/gma500: Use drm_dp_enhanced_frame_cap()

[Jani Nikula]

On Thu, 29 Oct 2026, Dmytro Malovanyi <dmitrymalovanyy@xxxxxxxxx> wrote:
> Use the helper instead of open coding the check, so enhanced framing is
> used for all DPCD r1.2+ sinks as the spec requires.
>
> The helper takes DP_RECEIVER_CAP_SIZE bytes and gcc warns about reading
> past dpcd[4] (-Wstringop-overread), so read the full receiver caps like
> the other drivers do. That is 15 bytes, it fits in one AUX transfer.
>
> Compile tested only.
>
> Signed-off-by: Dmytro Malovanyi <dmitrymalovanyy@xxxxxxxxx>

Reviewed-by: Jani Nikula <jani.nikula@xxxxxxxxx>

Ditto about drm_dp_read_dpcd_caps() usage.

> ---
>  drivers/gpu/drm/gma500/cdv_intel_dp.c | 8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/gma500/cdv_intel_dp.c b/drivers/gpu/drm/gma500/cdv_intel_dp.c
> index 8d0626ddf..0973598c7 100644
> --- a/drivers/gpu/drm/gma500/cdv_intel_dp.c
> +++ b/drivers/gpu/drm/gma500/cdv_intel_dp.c
> @@ -262,7 +262,7 @@ struct cdv_intel_dp {
>  	uint32_t color_range;
>  	uint8_t link_bw;
>  	uint8_t lane_count;
> -	uint8_t dpcd[4];
> +	uint8_t dpcd[DP_RECEIVER_CAP_SIZE];
>  	struct gma_encoder *encoder;
>  	struct i2c_adapter adapter;
>  	struct i2c_algo_dp_aux_data algo;
> @@ -1070,11 +1070,7 @@ cdv_intel_dp_mode_set(struct drm_encoder *encoder, struct drm_display_mode *mode
>  	intel_dp->link_configuration[0] = intel_dp->link_bw;
>  	intel_dp->link_configuration[1] = intel_dp->lane_count;
>  
> -	/*
> -	 * Check for DPCD version > 1.1 and enhanced framing support
> -	 */
> -	if (intel_dp->dpcd[DP_DPCD_REV] >= 0x11 &&
> -	    (intel_dp->dpcd[DP_MAX_LANE_COUNT] & DP_ENHANCED_FRAME_CAP)) {
> +	if (drm_dp_enhanced_frame_cap(intel_dp->dpcd)) {
>  		intel_dp->link_configuration[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN;
>  		intel_dp->DP |= DP_ENHANCED_FRAMING;
>  	}

-- 
Jani Nikula, Intel