drm/gma500: fbdev: Calculate buffer geometry with format helpers

Replace the geometry and size calculation in gma500's fbdev emulation
with DRM format helpers. This consists of 4CC lookup from the fbdev
parameters, format loockup, pitch calculation and size calculation.
Then allocate the GEM buffer object for the framebuffer memory from
the calculated size.

As before, fallback to 16-bit colors if the stolen memory is insufficient
for 32-bit colors. But look at the result from psb_gem_create() instead
of guessing before the allocation. The new method is more reliable when
others allocate from stolen video memory (e.g., cursors).

Set up mode_cmd with the calculated values just before allocating the
framebuffer. This code will later be replaced with a DRM client buffer.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Link: https://patch.msgid.link/20260206133458.226467-4-tzimmermann@suse.de

diff --git a/drivers/gpu/drm/gma500/fbdev.c b/drivers/gpu/drm/gma500/fbdev.c
index f5e60ada6de252a125b1c2b1d44938aa6fccc581..a93c3d2fe0ff3ee28f7646d1b618d672a12729c2 100644 (file)
--- a/drivers/gpu/drm/gma500/fbdev.c
+++ b/drivers/gpu/drm/gma500/fbdev.c
@@ -109,56 +109,52 @@ int psb_fbdev_driver_fbdev_probe(struct drm_fb_helper *fb_helper,
        struct drm_psb_private *dev_priv = to_drm_psb_private(dev);
        struct pci_dev *pdev = to_pci_dev(dev->dev);
        struct fb_info *info = fb_helper->info;
+       u32 fourcc, pitch;
+       u64 size;
+       const struct drm_format_info *format;
        struct drm_framebuffer *fb;
        struct drm_mode_fb_cmd2 mode_cmd = { };
-       int size;
        int ret;
        struct psb_gem_object *backing;
        struct drm_gem_object *obj;
-       u32 bpp, depth;
 
        /* No 24-bit packed mode */
        if (sizes->surface_bpp == 24) {
                sizes->surface_bpp = 32;
                sizes->surface_depth = 24;
        }
-       bpp = sizes->surface_bpp;
-       depth = sizes->surface_depth;
 
-       /*
-        * If the mode does not fit in 32 bit then switch to 16 bit to get
-        * a console on full resolution. The X mode setting server will
-        * allocate its own 32-bit GEM framebuffer.
-        */
-       size = ALIGN(sizes->surface_width * DIV_ROUND_UP(bpp, 8), 64) *
-                    sizes->surface_height;
-       size = ALIGN(size, PAGE_SIZE);
+try_psb_gem_create:
+       fourcc = drm_mode_legacy_fb_format(sizes->surface_bpp, sizes->surface_depth);
+       format = drm_get_format_info(dev, fourcc, DRM_FORMAT_MOD_LINEAR);
+       pitch = ALIGN(drm_format_info_min_pitch(format, 0, sizes->surface_width), SZ_64);
+       size = ALIGN(pitch * sizes->surface_height, PAGE_SIZE);
 
-       if (size > dev_priv->vram_stolen_size) {
-               sizes->surface_bpp = 16;
-               sizes->surface_depth = 16;
+       /* Allocate the framebuffer in the GTT with stolen page backing */
+       backing = psb_gem_create(dev, size, "fb", true, PAGE_SIZE);
+       if (IS_ERR(backing)) {
+               ret = PTR_ERR(backing);
+               if (ret == -EBUSY && sizes->surface_bpp > 16) {
+                       /*
+                        * If the mode does not fit in 32 bit then switch to 16 bit to
+                        * get a console on full resolution. User-space compositors will
+                        * allocate their own 32-bit framebuffers.
+                        */
+                       sizes->surface_bpp = 16;
+                       sizes->surface_depth = 16;
+                       goto try_psb_gem_create;
+               }
+               return ret;
        }
-       bpp = sizes->surface_bpp;
-       depth = sizes->surface_depth;
+       obj = &backing->base;
 
        mode_cmd.width = sizes->surface_width;
        mode_cmd.height = sizes->surface_height;
-       mode_cmd.pitches[0] = ALIGN(mode_cmd.width * DIV_ROUND_UP(bpp, 8), 64);
-       mode_cmd.pixel_format = drm_mode_legacy_fb_format(bpp, depth);
-
-       size = mode_cmd.pitches[0] * mode_cmd.height;
-       size = ALIGN(size, PAGE_SIZE);
-
-       /* Allocate the framebuffer in the GTT with stolen page backing */
-       backing = psb_gem_create(dev, size, "fb", true, PAGE_SIZE);
-       if (IS_ERR(backing))
-               return PTR_ERR(backing);
-       obj = &backing->base;
+       mode_cmd.pixel_format = fourcc;
+       mode_cmd.pitches[0] = pitch;
+       mode_cmd.modifier[0] = DRM_FORMAT_MOD_LINEAR;
 
-       fb = psb_framebuffer_create(dev,
-                                   drm_get_format_info(dev, mode_cmd.pixel_format,
-                                                       mode_cmd.modifier[0]),
-                                   &mode_cmd, obj);
+       fb = psb_framebuffer_create(dev, format, &mode_cmd, obj);
        if (IS_ERR(fb)) {
                ret = PTR_ERR(fb);
                goto err_drm_gem_object_put;