From eed65b99bea32412061c7e79646d17cb9062a982 Mon Sep 17 00:00:00 2001
From: Thomas Zimmermann <tzimmermann@suse.de>
Date: Mon, 25 Apr 2022 09:59:38 +0200
Subject: drm/format-helper: Add RGB888-to-XRGB8888 conversion
Git-commit: 26c30f223123b7feff0ca8722af2f93935b08b85
Patch-mainline: v5.19-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

Add a format helper that converts RGB888 to XRGB8888. Use this
function in drm_fb_blit_toio(). Fixes simpledrm output for this
combination of formats.

UEFI and/or Grub will usually set 32-bit output in XRGB8888 format.
The issue can be reproduced by enabling simpledrm and requesting a
console framebuffer of different format on the kernel command line;
for example

  nomodeset video=1024x768-24

In this case, conversion helpers will display nothing on the console.
The patch makes this work by implementing the rsp conversion helpers.
It also enables odd userspace configurations, such as running Xorg
with 24-bit color depth on a 32-bit output buffer.

v2:
	* use helpers for struct drm_rect (Javier)
	* improve commit message (Javier)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220425075939.30450-3-tzimmermann@suse.de
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/drm_format_helper.c | 46 +++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
index b648f29b21b6..c83e0bb2e8c7 100644
--- a/drivers/gpu/drm/drm_format_helper.c
+++ b/drivers/gpu/drm/drm_format_helper.c
@@ -411,6 +411,47 @@ void drm_fb_xrgb8888_to_rgb888_toio(void __iomem *dst, unsigned int dst_pitch,
 }
 EXPORT_SYMBOL(drm_fb_xrgb8888_to_rgb888_toio);
 
+static void drm_fb_rgb888_to_xrgb8888_line(void *dbuf, const void *sbuf, unsigned int pixels)
+{
+	u32 *dbuf32 = dbuf;
+	const u8 *sbuf8 = sbuf;
+	unsigned int x;
+
+	for (x = 0; x < pixels; x++) {
+		u8 r = *sbuf8++;
+		u8 g = *sbuf8++;
+		u8 b = *sbuf8++;
+		*dbuf32++ = 0xff000000 | (r << 16) | (g << 8) | b;
+	}
+}
+
+static void drm_fb_rgb888_to_xrgb8888_toio(void __iomem *dst, unsigned int dst_pitch,
+					   const void *vaddr, const struct drm_framebuffer *fb,
+					   const struct drm_rect *clip)
+{
+	size_t linepixels = drm_rect_width(clip);
+	size_t dst_len = linepixels * 4;
+	unsigned int y, lines = drm_rect_height(clip);
+	void *dbuf;
+
+	if (!dst_pitch)
+		dst_pitch = dst_len;
+
+	dbuf = kmalloc(dst_len, GFP_KERNEL);
+	if (!dbuf)
+		return;
+
+	vaddr += clip_offset(clip, fb->pitches[0], 3);
+	for (y = 0; y < lines; y++) {
+		drm_fb_rgb888_to_xrgb8888_line(dbuf, vaddr, linepixels);
+		memcpy_toio(dst, dbuf, dst_len);
+		vaddr += fb->pitches[0];
+		dst += dst_pitch;
+	}
+
+	kfree(dbuf);
+}
+
 static void drm_fb_xrgb8888_to_xrgb2101010_line(u32 *dbuf, const u32 *sbuf,
 						unsigned int pixels)
 {
@@ -583,6 +624,11 @@ int drm_fb_blit_toio(void __iomem *dst, unsigned int dst_pitch, uint32_t dst_for
 			drm_fb_xrgb8888_to_rgb888_toio(dst, dst_pitch, vmap, fb, clip);
 			return 0;
 		}
+	} else if (dst_format == DRM_FORMAT_XRGB8888) {
+		if (fb_format == DRM_FORMAT_RGB888) {
+			drm_fb_rgb888_to_xrgb8888_toio(dst, dst_pitch, vmap, fb, clip);
+			return 0;
+		}
 	} else if (dst_format == DRM_FORMAT_XRGB2101010) {
 		if (fb_format == DRM_FORMAT_XRGB8888) {
 			drm_fb_xrgb8888_to_xrgb2101010_toio(dst, dst_pitch, vmap, fb, clip);
-- 
2.38.1