Re: [PATCH v2 2/2] drm/vkms: Fix RGB565 pixel conversion

[Arthur Grillo Queiroz Cabral <arthurgrillo@riseup.net>]

On 07/05/23 17:28, Maíra Canal wrote:
> Currently, the pixel conversion isn't rounding the fixed-point values
> before assigning it to the RGB coefficients, which is causing the IGT
> pixel-format tests to fail. So, use the drm_fixp2int_round() fixed-point
> helper to round the values when assigning it to the RGB coefficients.
> 
> Tested with igt@kms_plane@pixel-format and igt@kms_plane@pixel-format-source-clamping.
> 
> Fixes: 89b03aeaef16 ("drm/vkms: fix 32bit compilation error by replacing macros")
> Signed-off-by: Maíra Canal <mcanal@igalia.com>
> ---

Reviewed-by: Arthur Grillo <arthurgrillo@riseup.net>

Best Regards,
~Arthur Grillo

> 
> v1 -> v2: https://lore.kernel.org/dri-devel/20230425153353.238844-1-mcanal@igalia.com/T/
> 
> * Use drm_fixp2int_round() to fix the pixel conversion instead of casting
>   the values to s32 (Melissa Wen).
> 
> ---
>  drivers/gpu/drm/vkms/vkms_formats.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vkms/vkms_formats.c b/drivers/gpu/drm/vkms/vkms_formats.c
> index 8d948c73741e..b11342026485 100644
> --- a/drivers/gpu/drm/vkms/vkms_formats.c
> +++ b/drivers/gpu/drm/vkms/vkms_formats.c
> @@ -97,9 +97,9 @@ static void RGB565_to_argb_u16(u8 *src_pixels, struct pixel_argb_u16 *out_pixel)
>  	s64 fp_b = drm_int2fixp(rgb_565 & 0x1f);
>  
>  	out_pixel->a = (u16)0xffff;
> -	out_pixel->r = drm_fixp2int(drm_fixp_mul(fp_r, fp_rb_ratio));
> -	out_pixel->g = drm_fixp2int(drm_fixp_mul(fp_g, fp_g_ratio));
> -	out_pixel->b = drm_fixp2int(drm_fixp_mul(fp_b, fp_rb_ratio));
> +	out_pixel->r = drm_fixp2int_round(drm_fixp_mul(fp_r, fp_rb_ratio));
> +	out_pixel->g = drm_fixp2int_round(drm_fixp_mul(fp_g, fp_g_ratio));
> +	out_pixel->b = drm_fixp2int_round(drm_fixp_mul(fp_b, fp_rb_ratio));
>  }
>  
>  void vkms_compose_row(struct line_buffer *stage_buffer, struct vkms_plane_state *plane, int y)
> @@ -216,9 +216,9 @@ static void argb_u16_to_RGB565(struct vkms_frame_info *frame_info,
>  		s64 fp_g = drm_int2fixp(in_pixels[x].g);
>  		s64 fp_b = drm_int2fixp(in_pixels[x].b);
>  
> -		u16 r = drm_fixp2int(drm_fixp_div(fp_r, fp_rb_ratio));
> -		u16 g = drm_fixp2int(drm_fixp_div(fp_g, fp_g_ratio));
> -		u16 b = drm_fixp2int(drm_fixp_div(fp_b, fp_rb_ratio));
> +		u16 r = drm_fixp2int_round(drm_fixp_div(fp_r, fp_rb_ratio));
> +		u16 g = drm_fixp2int_round(drm_fixp_div(fp_g, fp_g_ratio));
> +		u16 b = drm_fixp2int_round(drm_fixp_div(fp_b, fp_rb_ratio));
>  
>  		*dst_pixels = cpu_to_le16(r << 11 | g << 5 | b);
>  	}