Re: [PATCH v4 1/8] drm/vkms: Create helpers macro to avoid code duplication in format callbacks

["Maíra Canal" <mcanal@igalia.com>]

On 5/30/25 11:05, Louis Chauvet wrote:
> The callback functions for line conversion are almost identical for
> some format. The generic READ_LINE macro generate all the required
> boilerplate to process a line.
> 
> Two overrides of this macro have been added to avoid duplication of
> the same arguments every time.
> 
> Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>

Reviewed-by: Maíra Canal <mcanal@igalia.com>

Best Regards,
- Maíra

> ---
>   drivers/gpu/drm/vkms/vkms_formats.c | 186 ++++++++++++------------------------
>   1 file changed, 59 insertions(+), 127 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vkms/vkms_formats.c b/drivers/gpu/drm/vkms/vkms_formats.c
> index 6d0227c6635a..a9c624081dac 100644
> --- a/drivers/gpu/drm/vkms/vkms_formats.c
> +++ b/drivers/gpu/drm/vkms/vkms_formats.c
> @@ -292,6 +292,58 @@ VISIBLE_IF_KUNIT struct pixel_argb_u16 argb_u16_from_yuv888(u8 y, u8 channel_1,
>   }
>   EXPORT_SYMBOL_IF_KUNIT(argb_u16_from_yuv888);
>   
> +/**
> + * READ_LINE() - Generic generator for a read_line function which can be used for format with one
> + * plane and a block_h == block_w == 1.
> + *
> + * @function_name: Function name to generate
> + * @pixel_name: Temporary pixel name used in the @__VA_ARGS__ parameters
> + * @pixel_type: Used to specify the type you want to cast the pixel pointer
> + * @callback: Callback to call for each pixels. This fonction should take @__VA_ARGS__ as parameter
> + *            and return a pixel_argb_u16
> + * @__VA_ARGS__: Argument to pass inside the callback. You can use @pixel_name to access current
> + *  pixel.
> + */
> +#define READ_LINE(function_name, pixel_name, pixel_type, callback, ...)				\
> +static void function_name(const struct vkms_plane_state *plane, int x_start,			\
> +			      int y_start, enum pixel_read_direction direction, int count,	\
> +			      struct pixel_argb_u16 out_pixel[])				\
> +{												\
> +	struct pixel_argb_u16 *end = out_pixel + count;						\
> +	int step = get_block_step_bytes(plane->frame_info->fb, direction, 0);			\
> +	u8 *src_pixels;										\
> +												\
> +	packed_pixels_addr_1x1(plane->frame_info, x_start, y_start, 0, &src_pixels);		\
> +												\
> +	while (out_pixel < end) {								\
> +		pixel_type *(pixel_name) = (pixel_type *)src_pixels;				\
> +		*out_pixel = (callback)(__VA_ARGS__);						\
> +		out_pixel += 1;									\
> +		src_pixels += step;								\
> +	}											\
> +}
> +
> +/**
> + * READ_LINE_ARGB8888() - Generic generator for ARGB8888 formats.
> + * The pixel type used is u8, so pixel_name[0]..pixel_name[n] are the n components of the pixel.
> + *
> + * @function_name: Function name to generate
> + * @pixel_name: temporary pixel to use in @a, @r, @g and @b parameters
> + * @a, @r, @g, @b: value of each channel
> + */
> +#define READ_LINE_ARGB8888(function_name, pixel_name, a, r, g, b) \
> +	READ_LINE(function_name, pixel_name, u8, argb_u16_from_u8888, a, r, g, b)
> +/**
> + * READ_LINE_le16161616() - Generic generator for ARGB16161616 formats.
> + * The pixel type used is u16, so pixel_name[0]..pixel_name[n] are the n components of the pixel.
> + *
> + * @function_name: Function name to generate
> + * @pixel_name: temporary pixel to use in @a, @r, @g and @b parameters
> + * @a, @r, @g, @b: value of each channel
> + */
> +#define READ_LINE_le16161616(function_name, pixel_name, a, r, g, b) \
> +	READ_LINE(function_name, pixel_name, __le16, argb_u16_from_le16161616, a, r, g, b)
> +
>   /*
>    * The following functions are read_line function for each pixel format supported by VKMS.
>    *
> @@ -378,138 +430,18 @@ static void R4_read_line(const struct vkms_plane_state *plane, int x_start,
>   	Rx_read_line(plane, x_start, y_start, direction, count, out_pixel);
>   }
>   
> -static void R8_read_line(const struct vkms_plane_state *plane, int x_start,
> -			 int y_start, enum pixel_read_direction direction, int count,
> -			 struct pixel_argb_u16 out_pixel[])
> -{
> -	struct pixel_argb_u16 *end = out_pixel + count;
> -	u8 *src_pixels;
> -	int step = get_block_step_bytes(plane->frame_info->fb, direction, 0);
>   
> -	packed_pixels_addr_1x1(plane->frame_info, x_start, y_start, 0, &src_pixels);
> +READ_LINE_ARGB8888(XRGB8888_read_line, px, 0xFF, px[2], px[1], px[0])
>   
> -	while (out_pixel < end) {
> -		*out_pixel = argb_u16_from_gray8(*src_pixels);
> -		src_pixels += step;
> -		out_pixel += 1;
> -	}
> -}
> +READ_LINE_ARGB8888(ARGB8888_read_line, px, px[3], px[2], px[1], px[0])
> +READ_LINE_ARGB8888(ABGR8888_read_line, px, px[3], px[0], px[1], px[2])
>   
> -static void ARGB8888_read_line(const struct vkms_plane_state *plane, int x_start, int y_start,
> -			       enum pixel_read_direction direction, int count,
> -			       struct pixel_argb_u16 out_pixel[])
> -{
> -	struct pixel_argb_u16 *end = out_pixel + count;
> -	u8 *src_pixels;
> -
> -	packed_pixels_addr_1x1(plane->frame_info, x_start, y_start, 0, &src_pixels);
> +READ_LINE_le16161616(ARGB16161616_read_line, px, px[3], px[2], px[1], px[0])
> +READ_LINE_le16161616(XRGB16161616_read_line, px, cpu_to_le16(0xFFFF), px[2], px[1], px[0])
>   
> -	int step = get_block_step_bytes(plane->frame_info->fb, direction, 0);
> +READ_LINE(RGB565_read_line, px, __le16, argb_u16_from_RGB565, px)
>   
> -	while (out_pixel < end) {
> -		u8 *px = (u8 *)src_pixels;
> -		*out_pixel = argb_u16_from_u8888(px[3], px[2], px[1], px[0]);
> -		out_pixel += 1;
> -		src_pixels += step;
> -	}
> -}
> -
> -static void XRGB8888_read_line(const struct vkms_plane_state *plane, int x_start, int y_start,
> -			       enum pixel_read_direction direction, int count,
> -			       struct pixel_argb_u16 out_pixel[])
> -{
> -	struct pixel_argb_u16 *end = out_pixel + count;
> -	u8 *src_pixels;
> -
> -	packed_pixels_addr_1x1(plane->frame_info, x_start, y_start, 0, &src_pixels);
> -
> -	int step = get_block_step_bytes(plane->frame_info->fb, direction, 0);
> -
> -	while (out_pixel < end) {
> -		u8 *px = (u8 *)src_pixels;
> -		*out_pixel = argb_u16_from_u8888(255, px[2], px[1], px[0]);
> -		out_pixel += 1;
> -		src_pixels += step;
> -	}
> -}
> -
> -static void ABGR8888_read_line(const struct vkms_plane_state *plane, int x_start, int y_start,
> -			       enum pixel_read_direction direction, int count,
> -			       struct pixel_argb_u16 out_pixel[])
> -{
> -	struct pixel_argb_u16 *end = out_pixel + count;
> -	u8 *src_pixels;
> -
> -	packed_pixels_addr_1x1(plane->frame_info, x_start, y_start, 0, &src_pixels);
> -
> -	int step = get_block_step_bytes(plane->frame_info->fb, direction, 0);
> -
> -	while (out_pixel < end) {
> -		u8 *px = (u8 *)src_pixels;
> -		/* Switch blue and red pixels. */
> -		*out_pixel = argb_u16_from_u8888(px[3], px[0], px[1], px[2]);
> -		out_pixel += 1;
> -		src_pixels += step;
> -	}
> -}
> -
> -static void ARGB16161616_read_line(const struct vkms_plane_state *plane, int x_start,
> -				   int y_start, enum pixel_read_direction direction, int count,
> -				   struct pixel_argb_u16 out_pixel[])
> -{
> -	struct pixel_argb_u16 *end = out_pixel + count;
> -	u8 *src_pixels;
> -
> -	packed_pixels_addr_1x1(plane->frame_info, x_start, y_start, 0, &src_pixels);
> -
> -	int step = get_block_step_bytes(plane->frame_info->fb, direction, 0);
> -
> -	while (out_pixel < end) {
> -		u16 *px = (u16 *)src_pixels;
> -		*out_pixel = argb_u16_from_u16161616(px[3], px[2], px[1], px[0]);
> -		out_pixel += 1;
> -		src_pixels += step;
> -	}
> -}
> -
> -static void XRGB16161616_read_line(const struct vkms_plane_state *plane, int x_start,
> -				   int y_start, enum pixel_read_direction direction, int count,
> -				   struct pixel_argb_u16 out_pixel[])
> -{
> -	struct pixel_argb_u16 *end = out_pixel + count;
> -	u8 *src_pixels;
> -
> -	packed_pixels_addr_1x1(plane->frame_info, x_start, y_start, 0, &src_pixels);
> -
> -	int step = get_block_step_bytes(plane->frame_info->fb, direction, 0);
> -
> -	while (out_pixel < end) {
> -		__le16 *px = (__le16 *)src_pixels;
> -		*out_pixel = argb_u16_from_le16161616(cpu_to_le16(0xFFFF), px[2], px[1], px[0]);
> -		out_pixel += 1;
> -		src_pixels += step;
> -	}
> -}
> -
> -static void RGB565_read_line(const struct vkms_plane_state *plane, int x_start,
> -			     int y_start, enum pixel_read_direction direction, int count,
> -			     struct pixel_argb_u16 out_pixel[])
> -{
> -	struct pixel_argb_u16 *end = out_pixel + count;
> -	u8 *src_pixels;
> -
> -	packed_pixels_addr_1x1(plane->frame_info, x_start, y_start, 0, &src_pixels);
> -
> -	int step = get_block_step_bytes(plane->frame_info->fb, direction, 0);
> -
> -	while (out_pixel < end) {
> -		__le16 *px = (__le16 *)src_pixels;
> -
> -		*out_pixel = argb_u16_from_RGB565(px);
> -		out_pixel += 1;
> -		src_pixels += step;
> -	}
> -}
> +READ_LINE(R8_read_line, px, u8, argb_u16_from_gray8, *px)
>   
>   /*
>    * This callback can be used for YUV formats where U and V values are
>