Re: [PATCH v2] drm/log: Batch vmap/vunmap and flush for record drawing

On 30/07/2026 12:59, [email protected] wrote:
> From: Shixiong Ou <[email protected]>
> 
> drm_log_draw_new_line() calls drm_log_clear_line() and drm_log_draw_line(),
> which independently call drm_client_buffer_vmap_local(),
> drm_client_buffer_vunmap_local(), and drm_client_buffer_flush(). For each
> call to drm_log_draw_new_line(), this results in 2 vmap/vunmap pairs and
> 2 flush calls, even though vmap_local maps the entire framebuffer
> each time.
> 
> Refactor drm_log_clear_line() and drm_log_draw_line() to accept a
> pre-mapped iosys_map by value, removing the per-line vmap/vunmap/flush
> calls. Move the single vmap/vunmap pair and flush up to
> drm_log_draw_new_line(), which now maps once before clearing and
> drawing, then issues a single flush after unmapping.
> 
> Also remove the now-unused drm_rect from both functions.

Thanks, it looks good to me.

Reviewed-by: Jocelyn Falempe <[email protected]>

> 
> Signed-off-by: Shixiong Ou <[email protected]>
> ---
> v1->v2:
>     Remove unused drm_rect from drm_log_clear_line() and
>     drm_log_draw_line().
> 
> diff --git a/drivers/gpu/drm/clients/drm_log.c b/drivers/gpu/drm/clients/drm_log.c
> index ac10c978f917..52563e2a1c45 100644
> --- a/drivers/gpu/drm/clients/drm_log.c
> +++ b/drivers/gpu/drm/clients/drm_log.c
> @@ -94,37 +94,28 @@ static void drm_log_blit(struct iosys_map *dst, unsigned int dst_pitch,
>   	}
>   }
>   
> -static void drm_log_clear_line(struct drm_log_scanout *scanout, u32 line)
> +static void drm_log_clear_line(struct drm_log_scanout *scanout, u32 line,
> +			       struct iosys_map map)
>   {
>   	struct drm_framebuffer *fb = scanout->buffer->fb;
>   	unsigned long height = scanout->scaled_font_h;
> -	struct iosys_map map;
> -	struct drm_rect r = DRM_RECT_INIT(0, line * height, fb->width, height);
>   
> -	if (drm_client_buffer_vmap_local(scanout->buffer, &map))
> -		return;
> -	iosys_map_memset(&map, r.y1 * fb->pitches[0], 0, height * fb->pitches[0]);
> -	drm_client_buffer_vunmap_local(scanout->buffer);
> -	drm_client_buffer_flush(scanout->buffer, &r);
> +	iosys_map_memset(&map, line * height * fb->pitches[0], 0, height * fb->pitches[0]);
>   }
>   
>   static void drm_log_draw_line(struct drm_log_scanout *scanout, const char *s,
> -			      unsigned int len, unsigned int prefix_len)
> +			      unsigned int len, unsigned int prefix_len,
> +			      struct iosys_map map)
>   {
>   	struct drm_framebuffer *fb = scanout->buffer->fb;
> -	struct iosys_map map;
>   	const struct font_desc *font = scanout->font;
>   	size_t font_pitch = DIV_ROUND_UP(font->width, 8);
>   	const u8 *src;
>   	u32 px_width = fb->format->cpp[0];
> -	struct drm_rect r = DRM_RECT_INIT(0, scanout->line * scanout->scaled_font_h,
> -					  fb->width, (scanout->line + 1) * scanout->scaled_font_h);
>   	u32 i;
>   
> -	if (drm_client_buffer_vmap_local(scanout->buffer, &map))
> -		return;
> +	iosys_map_incr(&map, scanout->line * scanout->scaled_font_h * fb->pitches[0]);
>   
> -	iosys_map_incr(&map, r.y1 * fb->pitches[0]);
>   	for (i = 0; i < len && i < scanout->columns; i++) {
>   		u32 color = (i < prefix_len) ? scanout->prefix_color : scanout->front_color;
>   		src = font_data_glyph_buf(font->data, font->width, font->height,
> @@ -139,21 +130,40 @@ static void drm_log_draw_line(struct drm_log_scanout *scanout, const char *s,
>   	scanout->line++;
>   	if (scanout->line >= scanout->rows)
>   		scanout->line = 0;
> -	drm_client_buffer_vunmap_local(scanout->buffer);
> -	drm_client_buffer_flush(scanout->buffer, &r);
>   }
>   
>   static void drm_log_draw_new_line(struct drm_log_scanout *scanout,
> -				  const char *s, unsigned int len, unsigned int prefix_len)
> +				  const char *s, unsigned int len,
> +				  unsigned int prefix_len)
>   {
> +	struct iosys_map map;
> +	struct drm_framebuffer *fb = scanout->buffer->fb;
> +	u32 height = scanout->scaled_font_h;
> +	u32 line = scanout->line;
> +	u32 y2;
> +	struct drm_rect dirty;
> +
> +	if (drm_client_buffer_vmap_local(scanout->buffer, &map))
> +		return;
> +
>   	if (scanout->line == 0) {
> -		drm_log_clear_line(scanout, 0);
> -		drm_log_clear_line(scanout, 1);
> -		drm_log_clear_line(scanout, 2);
> -	} else if (scanout->line + 2 < scanout->rows)
> -		drm_log_clear_line(scanout, scanout->line + 2);
> +		drm_log_clear_line(scanout, 0, map);
> +		drm_log_clear_line(scanout, 1, map);
> +		drm_log_clear_line(scanout, 2, map);
> +		y2 = min(3, scanout->rows) * height;
> +	} else if (scanout->line + 2 < scanout->rows) {
> +		drm_log_clear_line(scanout, scanout->line + 2, map);
> +		y2 = (line + 3) * height;
> +	} else {
> +		y2 = (line + 1) * height;
> +	}
> +
> +	drm_log_draw_line(scanout, s, len, prefix_len, map);
> +
> +	drm_client_buffer_vunmap_local(scanout->buffer);
>   
> -	drm_log_draw_line(scanout, s, len, prefix_len);
> +	dirty = DRM_RECT_INIT(0, line * height, fb->width, y2 - line * height);
> +	drm_client_buffer_flush(scanout->buffer, &dirty);
>   }
>   
>   /*
> --
> 2.25.1
> 
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