panfrost: Determine framebuffer format bits late

Again, these formats are only properly known at the time of fragment job
emit. Rather than hardcoding the format, at least for MFBD we begin to
construct the format bits on-demand. This cleans up the code,
futureproofs for ES3 framebuffer formats, and should fix bugs regarding
FBO colour swizzles.

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Tomeu Vizoso <tomeu.visozo@collabora.com>

src/gallium/drivers/panfrost/pan_context.c

@@ -131,6 +131,35 @@ panfrost_enable_checksum(struct panfrost_context *ctx, struct panfrost_resource
         rsrc->bo->has_checksum = true;
 }
 
+static unsigned
+panfrost_sfbd_format_for_surface(struct pipe_surface *surf)
+{
+        /* TODO */
+        return 0xb84e0281; /* RGB32, no MSAA */
+}
+
+static struct mali_rt_format
+panfrost_mfbd_format_for_surface(struct pipe_surface *surf)
+{
+        /* Explode details on the format */
+
+        const struct util_format_description *desc =
+                util_format_description(surf->texture->format);
+
+        /* Fill in accordingly */
+
+        struct mali_rt_format fmt = {
+                .unk1 = 0x4000000,
+                .unk2 = 0x1,
+                .nr_channels = MALI_POSITIVE(desc->nr_channels),
+                .flags = 0x444,
+                .swizzle = panfrost_translate_swizzle_4(desc->swizzle),
+                .unk4 = 0x8
+        };
+
+        return fmt;
+}
+
 static bool panfrost_is_scanout(struct panfrost_context *ctx);
 
 /* These routines link a fragment job with the bound surface, accounting for the
@@ -147,6 +176,18 @@ panfrost_set_fragment_target_cbuf(
         signed stride =
                 util_format_get_stride(surf->format, surf->texture->width0);
 
+        /* First, we set the format bits */
+
+        if (ctx->require_sfbd) {
+                ctx->fragment_sfbd.format =
+                        panfrost_sfbd_format_for_surface(surf);
+        } else {
+                ctx->fragment_rts[cb].format =
+                        panfrost_mfbd_format_for_surface(surf);
+        }
+
+        /* Now, we set the layout specific pieces */
+
         if (rsrc->bo->layout == PAN_LINEAR) {
                 mali_ptr framebuffer = rsrc->bo->gpu[0];
 
@@ -367,7 +408,6 @@ panfrost_new_frag_framebuffer(struct panfrost_context *ctx)
 {
         if (ctx->require_sfbd) {
                 struct mali_single_framebuffer fb = panfrost_emit_sfbd(ctx);
-                fb.format = 0xb84e0281; /* RGB32, no MSAA */
                 memcpy(&ctx->fragment_sfbd, &fb, sizeof(fb));
         } else {
                 struct bifrost_framebuffer fb = panfrost_emit_mfbd(ctx);
@@ -376,24 +416,9 @@ panfrost_new_frag_framebuffer(struct panfrost_context *ctx)
                 fb.rt_count_2 = 1;
                 fb.unk3 = 0x100;
 
-                /* By default, Gallium seems to need a BGR framebuffer */
-                unsigned char bgra[4] = {
-                        PIPE_SWIZZLE_Z, PIPE_SWIZZLE_Y, PIPE_SWIZZLE_X, PIPE_SWIZZLE_W
-                };
-
-                struct bifrost_render_target rt = {
-                        .format = {
-                                .unk1 = 0x4000000,
-                                .unk2 = 0x1,
-                                .nr_channels = MALI_POSITIVE(4),
-                                .flags = 0x444,
-                                .swizzle = panfrost_translate_swizzle_4(bgra),
-                                .unk4 = 0x8
-                        },
-                };
+                struct bifrost_render_target rt = {};
 
                 memcpy(&ctx->fragment_rts[0], &rt, sizeof(rt));
-
                 memset(&ctx->fragment_extra, 0, sizeof(ctx->fragment_extra));
                 memcpy(&ctx->fragment_mfbd, &fb, sizeof(fb));
         }