drm/fb-helper: Add support for DRM_FORMAT_C[124]

Add support for color-indexed frame buffer formats with two, four, and
sixteen colors to the DRM framebuffer helper functions:
  1. Add support for 1, 2, and 4 bits per pixel to the damage helper,
  2. For color-indexed modes, the length of the color bitfields must be
     set to the color depth, else the logo code may pick a logo with too
     many colors.  Drop the incorrect DAC width comment, which
     originates from the i915 driver.
  3. Accept C[124] modes when validating or filling in struct
     fb_var_screeninfo, and use the correct number of bits per pixel.
  4. Set the visual to FB_VISUAL_PSEUDOCOLOR for all color-indexed
     modes.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/db3e80b445df661ff0cd7e698507a8d24a4c867e.1657294931.git.geert@linux-m68k.org

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 2d4cee6..71edb80 100644 (file)
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -377,12 +377,31 @@ static void drm_fb_helper_damage_blit_real(struct drm_fb_helper *fb_helper,
                                           struct iosys_map *dst)
 {
        struct drm_framebuffer *fb = fb_helper->fb;
-       unsigned int cpp = fb->format->cpp[0];
-       size_t offset = clip->y1 * fb->pitches[0] + clip->x1 * cpp;
-       void *src = fb_helper->fbdev->screen_buffer + offset;
-       size_t len = (clip->x2 - clip->x1) * cpp;
+       size_t offset = clip->y1 * fb->pitches[0];
+       size_t len = clip->x2 - clip->x1;
        unsigned int y;
+       void *src;
 
+       switch (drm_format_info_bpp(fb->format, 0)) {
+       case 1:
+               offset += clip->x1 / 8;
+               len = DIV_ROUND_UP(len + clip->x1 % 8, 8);
+               break;
+       case 2:
+               offset += clip->x1 / 4;
+               len = DIV_ROUND_UP(len + clip->x1 % 4, 4);
+               break;
+       case 4:
+               offset += clip->x1 / 2;
+               len = DIV_ROUND_UP(len + clip->x1 % 2, 2);
+               break;
+       default:
+               offset += clip->x1 * fb->format->cpp[0];
+               len *= fb->format->cpp[0];
+               break;
+       }
+
+       src = fb_helper->fbdev->screen_buffer + offset;
        iosys_map_incr(dst, offset); /* go to first pixel within clip rect */
 
        for (y = clip->y1; y < clip->y2; y++) {
@@ -1274,19 +1293,23 @@ static bool drm_fb_pixel_format_equal(const struct fb_var_screeninfo *var_1,
 }
 
 static void drm_fb_helper_fill_pixel_fmt(struct fb_var_screeninfo *var,
-                                        u8 depth)
+                                        const struct drm_format_info *format)
 {
-       switch (depth) {
-       case 8:
+       u8 depth = format->depth;
+
+       if (format->is_color_indexed) {
                var->red.offset = 0;
                var->green.offset = 0;
                var->blue.offset = 0;
-               var->red.length = 8; /* 8bit DAC */
-               var->green.length = 8;
-               var->blue.length = 8;
+               var->red.length = depth;
+               var->green.length = depth;
+               var->blue.length = depth;
                var->transp.offset = 0;
                var->transp.length = 0;
-               break;
+               return;
+       }
+
+       switch (depth) {
        case 15:
                var->red.offset = 10;
                var->green.offset = 5;
@@ -1341,7 +1364,9 @@ int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
 {
        struct drm_fb_helper *fb_helper = info->par;
        struct drm_framebuffer *fb = fb_helper->fb;
+       const struct drm_format_info *format = fb->format;
        struct drm_device *dev = fb_helper->dev;
+       unsigned int bpp;
 
        if (in_dbg_master())
                return -EINVAL;
@@ -1351,22 +1376,33 @@ int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
                var->pixclock = 0;
        }
 
-       if ((drm_format_info_block_width(fb->format, 0) > 1) ||
-           (drm_format_info_block_height(fb->format, 0) > 1))
-               return -EINVAL;
+       switch (format->format) {
+       case DRM_FORMAT_C1:
+       case DRM_FORMAT_C2:
+       case DRM_FORMAT_C4:
+               /* supported format with sub-byte pixels */
+               break;
+
+       default:
+               if ((drm_format_info_block_width(format, 0) > 1) ||
+                   (drm_format_info_block_height(format, 0) > 1))
+                       return -EINVAL;
+               break;
+       }
 
        /*
         * Changes struct fb_var_screeninfo are currently not pushed back
         * to KMS, hence fail if different settings are requested.
         */
-       if (var->bits_per_pixel > fb->format->cpp[0] * 8 ||
+       bpp = drm_format_info_bpp(format, 0);
+       if (var->bits_per_pixel > bpp ||
            var->xres > fb->width || var->yres > fb->height ||
            var->xres_virtual > fb->width || var->yres_virtual > fb->height) {
                drm_dbg_kms(dev, "fb requested width/height/bpp can't fit in current fb "
                          "request %dx%d-%d (virtual %dx%d) > %dx%d-%d\n",
                          var->xres, var->yres, var->bits_per_pixel,
                          var->xres_virtual, var->yres_virtual,
-                         fb->width, fb->height, fb->format->cpp[0] * 8);
+                         fb->width, fb->height, bpp);
                return -EINVAL;
        }
 
@@ -1381,13 +1417,13 @@ int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
            !var->blue.length    && !var->transp.length   &&
            !var->red.msb_right  && !var->green.msb_right &&
            !var->blue.msb_right && !var->transp.msb_right) {
-               drm_fb_helper_fill_pixel_fmt(var, fb->format->depth);
+               drm_fb_helper_fill_pixel_fmt(var, format);
        }
 
        /*
         * Likewise, bits_per_pixel should be rounded up to a supported value.
         */
-       var->bits_per_pixel = fb->format->cpp[0] * 8;
+       var->bits_per_pixel = bpp;
 
        /*
         * drm fbdev emulation doesn't support changing the pixel format at all,
@@ -1723,11 +1759,11 @@ static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper,
 }
 
 static void drm_fb_helper_fill_fix(struct fb_info *info, uint32_t pitch,
-                                  uint32_t depth)
+                                  bool is_color_indexed)
 {
        info->fix.type = FB_TYPE_PACKED_PIXELS;
-       info->fix.visual = depth == 8 ? FB_VISUAL_PSEUDOCOLOR :
-               FB_VISUAL_TRUECOLOR;
+       info->fix.visual = is_color_indexed ? FB_VISUAL_PSEUDOCOLOR
+                                           : FB_VISUAL_TRUECOLOR;
        info->fix.mmio_start = 0;
        info->fix.mmio_len = 0;
        info->fix.type_aux = 0;
@@ -1744,19 +1780,31 @@ static void drm_fb_helper_fill_var(struct fb_info *info,
                                   uint32_t fb_width, uint32_t fb_height)
 {
        struct drm_framebuffer *fb = fb_helper->fb;
+       const struct drm_format_info *format = fb->format;
+
+       switch (format->format) {
+       case DRM_FORMAT_C1:
+       case DRM_FORMAT_C2:
+       case DRM_FORMAT_C4:
+               /* supported format with sub-byte pixels */
+               break;
+
+       default:
+               WARN_ON((drm_format_info_block_width(format, 0) > 1) ||
+                       (drm_format_info_block_height(format, 0) > 1));
+               break;
+       }
 
-       WARN_ON((drm_format_info_block_width(fb->format, 0) > 1) ||
-               (drm_format_info_block_height(fb->format, 0) > 1));
        info->pseudo_palette = fb_helper->pseudo_palette;
        info->var.xres_virtual = fb->width;
        info->var.yres_virtual = fb->height;
-       info->var.bits_per_pixel = fb->format->cpp[0] * 8;
+       info->var.bits_per_pixel = drm_format_info_bpp(format, 0);
        info->var.accel_flags = FB_ACCELF_TEXT;
        info->var.xoffset = 0;
        info->var.yoffset = 0;
        info->var.activate = FB_ACTIVATE_NOW;
 
-       drm_fb_helper_fill_pixel_fmt(&info->var, fb->format->depth);
+       drm_fb_helper_fill_pixel_fmt(&info->var, format);
 
        info->var.xres = fb_width;
        info->var.yres = fb_height;
@@ -1781,7 +1829,8 @@ void drm_fb_helper_fill_info(struct fb_info *info,
 {
        struct drm_framebuffer *fb = fb_helper->fb;
 
-       drm_fb_helper_fill_fix(info, fb->pitches[0], fb->format->depth);
+       drm_fb_helper_fill_fix(info, fb->pitches[0],
+                              fb->format->is_color_indexed);
        drm_fb_helper_fill_var(info, fb_helper,
                               sizes->fb_width, sizes->fb_height);