[PATCH] drm/amd/display: check attr flag before set cursor degamma on DCN3+

[Alex Hung]

Tested-by: Alex Hung <alex.hung at amd.com>

On 2023-07-31 02:35, Melissa Wen wrote:
> Don't set predefined degamma curve to cursor plane if the cursor
> attribute flag is not set. Applying a degamma curve to the cursor by
> default breaks userspace expectation. Checking the flag before
> performing any color transformation prevents too dark cursor gamma in
> DCN3+ on many Linux desktop environment (KDE Plasma, GNOME,
> wlroots-based, etc.) as reported at:
> - https://gitlab.freedesktop.org/drm/amd/-/issues/1513
> 
> This is the same approach followed by DCN2 drivers where the issue is
> not present.
> 
> Fixes: 03f54d7d3448 ("drm/amd/display: Add DCN3 DPP")
> Signed-off-by: Melissa Wen <mwen at igalia.com>
> ---
>   drivers/gpu/drm/amd/display/dc/dcn30/dcn30_dpp.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_dpp.c b/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_dpp.c
> index e5b7ef7422b8..50dc83404644 100644
> --- a/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_dpp.c
> +++ b/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_dpp.c
> @@ -357,8 +357,11 @@ void dpp3_set_cursor_attributes(
>   	int cur_rom_en = 0;
>   
>   	if (color_format == CURSOR_MODE_COLOR_PRE_MULTIPLIED_ALPHA ||
> -		color_format == CURSOR_MODE_COLOR_UN_PRE_MULTIPLIED_ALPHA)
> -		cur_rom_en = 1;
> +		color_format == CURSOR_MODE_COLOR_UN_PRE_MULTIPLIED_ALPHA) {
> +		if (cursor_attributes->attribute_flags.bits.ENABLE_CURSOR_DEGAMMA) {
> +			cur_rom_en = 1;
> +		}
> +	}
>   
>   	REG_UPDATE_3(CURSOR0_CONTROL,
>   			CUR0_MODE, color_format,