edid: Make framebuffer row alignment configurable

Our EDID code had always been aligning the framebuffer's
bytes_per_line (and x_resolution dependent on that) to 64. It turns out
that this is a controller-dependent parameter that seems to only really
be necessary for Intel chipsets, and commit 6911219cc (edid: Add helper
function to calculate bits-per-pixel dependent values) probably actually
broke this for some other controllers by applying the alignment too
widely.

This patch makes it explicitly configurable and depends the default on
ARCH_X86 (which seems to be the simplest and least intrusive way to make
it fit most cases for now... boards where this doesn't apply can still
override it manually by calling edid_set_framebuffer_bits_per_pixel()
again).

Change-Id: I1c565a72826fc5ddfbb1ae4a5db5e9063b761455
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/14267
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/drivers/emulation/qemu/bochs.c

@@ -113,7 +113,7 @@ static void bochs_init(struct device *dev)
 	edid.mode.va = height;
 	edid.panel_bits_per_color = 8;
 	edid.panel_bits_per_pixel = 24;
-	edid_set_framebuffer_bits_per_pixel(&edid, 32);
+	edid_set_framebuffer_bits_per_pixel(&edid, 32, 0);
 	set_vbe_mode_info_valid(&edid, addr);
 #else
 	vga_misc_write(0x1);

src/drivers/emulation/qemu/cirrus.c

@@ -332,7 +332,7 @@ static void cirrus_init(struct device *dev)
 	edid.mode.va = height;
 	edid.panel_bits_per_color = 8;
 	edid.panel_bits_per_pixel = 24;
-	edid_set_framebuffer_bits_per_pixel(&edid, 32);
+	edid_set_framebuffer_bits_per_pixel(&edid, 32, 0);
 	set_vbe_mode_info_valid(&edid, addr);
 #else
 	vga_misc_write(0x1);

src/include/edid.h

@@ -93,7 +93,8 @@ struct edid {
 
 /* Defined in src/lib/edid.c */
 int decode_edid(unsigned char *edid, int size, struct edid *out);
-void edid_set_framebuffer_bits_per_pixel(struct edid *edid, int fb_bpp);
+void edid_set_framebuffer_bits_per_pixel(struct edid *edid, int fb_bpp,
+					 int row_byte_alignment);
 void set_vbe_mode_info_valid(struct edid *edid, uintptr_t fb_addr);
 int set_display_mode(struct edid *edid, enum edid_modes mode);
 

src/lib/edid.c

@@ -481,9 +481,14 @@ detailed_block(struct edid *result_edid, unsigned char *x, int in_extension,
 	out->mode.vborder = x[16];
 
 	/* We assume rgb888 (32 bits per pixel) framebuffers by default.
-	 * Chipsets that want something else will need to override this
+	 * Chipsets that want something else will need to override this with
-	 * with another call to edid_set_framebuffer_bits_per_pixel(). */
+	 * another call to edid_set_framebuffer_bits_per_pixel(). As a cheap
-	edid_set_framebuffer_bits_per_pixel(out, 32);
+	 * heuristic, assume that X86 systems require a 64-byte row alignment
+	 * (since that seems to be true for most Intel chipsets). */
+	if (IS_ENABLED(CONFIG_ARCH_X86))
+		edid_set_framebuffer_bits_per_pixel(out, 32, 64);
+	else
+		edid_set_framebuffer_bits_per_pixel(out, 32, 0);
 
 	switch ((x[17] & 0x18) >> 3) {
 	case 0x00:
@@ -1524,14 +1529,16 @@ int decode_edid(unsigned char *edid, int size, struct edid *out)
  */
 
 /* Set the framebuffer bits-per-pixel, recalculating all dependent values. */
-void edid_set_framebuffer_bits_per_pixel(struct edid *edid, int fb_bpp)
+void edid_set_framebuffer_bits_per_pixel(struct edid *edid, int fb_bpp,
+					 int row_byte_alignment)
 {
 	/* Caller should pass a supported value, everything else is BUG(). */
 	assert(fb_bpp == 32 || fb_bpp == 24 || fb_bpp == 16);
+	row_byte_alignment = max(row_byte_alignment, 1);
 
 	edid->framebuffer_bits_per_pixel = fb_bpp;
 	edid->bytes_per_line = ALIGN_UP(edid->mode.ha *
-					div_round_up(fb_bpp, 8), 64);
+		div_round_up(fb_bpp, 8), row_byte_alignment);
 	edid->x_resolution = edid->bytes_per_line / (fb_bpp / 8);
 	edid->y_resolution = edid->mode.va;
 }

src/soc/nvidia/tegra124/display.c

@@ -334,6 +334,6 @@ void display_startup(device_t dev)
 	edid.mode.va = config->yres;
 	edid.mode.ha = config->xres;
 	edid_set_framebuffer_bits_per_pixel(&edid,
-					    config->framebuffer_bits_per_pixel);
+		config->framebuffer_bits_per_pixel, 0);
 	set_vbe_mode_info_valid(&edid, (uintptr_t)(framebuffer_base_mb*MiB));
 }

src/soc/nvidia/tegra132/dc.c

@@ -230,7 +230,7 @@ void pass_mode_info_to_payload(
 	edid.mode.va = config->display_yres;
 	edid.mode.ha = config->display_xres;
 	edid_set_framebuffer_bits_per_pixel(&edid,
-					    config->framebuffer_bits_per_pixel);
+		config->framebuffer_bits_per_pixel, 0);
 
 	printk(BIOS_INFO, "%s: bytes_per_line: %d, bits_per_pixel: %d\n "
 			"               x_res x y_res: %d x %d, size: %d\n",

src/soc/nvidia/tegra210/dc.c

@@ -230,7 +230,7 @@ void pass_mode_info_to_payload(
 	edid.mode.va = config->display_yres;
 	edid.mode.ha = config->display_xres;
 	edid_set_framebuffer_bits_per_pixel(&edid,
-					    config->framebuffer_bits_per_pixel);
+		config->framebuffer_bits_per_pixel, 0);
 
 	printk(BIOS_INFO, "%s: bytes_per_line: %d, bits_per_pixel: %d\n "
 			"               x_res x y_res: %d x %d, size: %d\n",

src/soc/rockchip/rk3288/display.c

@@ -95,7 +95,7 @@ void rk_display_init(device_t dev, u32 lcdbase,
 	}
 
 	edid_set_framebuffer_bits_per_pixel(&edid,
-					    conf->framebuffer_bits_per_pixel);
+		conf->framebuffer_bits_per_pixel, 0);
 	rkvop_mode_set(conf->vop_id, &edid, detected_mode);
 
 	rkvop_enable(conf->vop_id, lcdbase, &edid);