[PATCH v3 06/10] drm/fb-helper: Add support for DRM_FORMAT_C[124]

Geert Uytterhoeven
2022-07-08T18:21:16Z

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>
---
If "[PATCH] drm/fb-helper: Remove helpers to change frame buffer
config"[1] is accepted, the changes to drm_fb_helper_check_var() can
just be removed.

v3:
- Fix FB_VISUAL_TRUECOLOR,
- Add Reviewed-by,

v2:
- Use drm_format_info_bpp() helper instead of deprecated .depth field
or format-dependent calculations,
- Use new .is_color_indexed field instead of checking against a list
of formats.

[1] Link: https://lore.kernel.org/r/20220629105658.1373770-1-geert@linux-m68k.org
---
drivers/gpu/drm/drm_fb_helper.c | 101 ++++++++++++++++++++++++--------
1 file changed, 75 insertions(+), 26 deletions(-)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 1705e8d345aba50a..5098efb374fe64ed 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -376,12 +376,31 @@ 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++) {
@@ -1273,19 +1292,23 @@ 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;
@@ -1340,7 +1363,9 @@ 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;
@@ -1350,22 +1375,33 @@ 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;
}

@@ -1380,13 +1416,13 @@ 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,
@@ -1722,11 +1758,11 @@ 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;
@@ -1743,19 +1779,31 @@ 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;
@@ -1780,7 +1828,8 @@ 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);

--
2.25.1