[PATCH] radeon: acquire BIOS via firmware subsystem if everything else failed

[Wilfried Klaebe]

At least Apple's MacBook Pro 8,2 booting EFI -> GRUB2 -> Linux (without
BIOS emulation) seems to have no Radeon BIOS accessible via conventional
means. Loading one via firmware system previously dumped (with
"dd if=/dev/mem of=/lib/firmware/radeon/vbios.bin bs=65536 skip=12 count=1")
when booted with BIOS emulation works. I carry this patch around since
about 3.8 and never had any problems, not even with several dozen cycles
of suspend2ram and resume. Also, I tested every new release if this patch
was still necessary, and it always was.

Thanks to Stefan Dösinger and others at 
https://www.libreoffice.org/bugzilla/show_bug.cgi?id=26891

Signed-off-by: Wilfried Klaebe <w-lkml@xxxxxxxxxxxxxxxxxxxxxxxxxx>

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me if replying there.

diff --git a/drivers/gpu/drm/radeon/radeon_bios.c b/drivers/gpu/drm/radeon/radeon_bios.c
index 63ccb8f..cf55e0e 100644
--- a/drivers/gpu/drm/radeon/radeon_bios.c
+++ b/drivers/gpu/drm/radeon/radeon_bios.c
@@ -29,6 +29,7 @@
 #include "radeon_reg.h"
 #include "radeon.h"
 #include "atom.h"
+#include <linux/firmware.h>
 
 #include <linux/vga_switcheroo.h>
 #include <linux/slab.h>
@@ -74,6 +75,44 @@ static bool igp_read_bios_from_vram(struct radeon_device *rdev)
 	return true;
 }
 
+static bool radeon_read_bios_from_firmware(struct radeon_device *rdev)
+{
+	const uint8_t __iomem *bios;
+	resource_size_t size;
+	const struct firmware *fw = NULL;
+	char *err = NULL;
+
+	request_firmware(&fw, "radeon/vbios.bin", rdev->dev);
+	if (!fw) {
+		err = "firmware request returned NULL\n";
+		goto out;
+	}
+	size = fw->size;
+	bios = fw->data;
+
+	if (size == 0 || !bios) {
+		err = "firmware request returned zero sized or NULL data\n";
+		goto out;
+	}
+
+	if (bios[0] != 0x55 || bios[1] != 0xaa) {
+		err = "wrong signature on firmware\n";
+		goto out;
+	}
+	rdev->bios = kmalloc(size, GFP_KERNEL);
+	if (rdev->bios == NULL) {
+		err = "failed to kmalloc() memory for firmware\n";
+		goto out;
+	}
+	memcpy(rdev->bios, bios, size);
+out:
+	if (err)
+		DRM_ERROR(err);
+	if (fw)
+		release_firmware(fw);
+	return !err;
+}
+
 static bool radeon_read_bios(struct radeon_device *rdev)
 {
 	uint8_t __iomem *bios;
@@ -662,6 +701,8 @@ bool radeon_get_bios(struct radeon_device *rdev)
 		r = radeon_read_disabled_bios(rdev);
 	if (r == false)
 		r = radeon_read_platform_bios(rdev);
+	if (r == false)
+		r = radeon_read_bios_from_firmware(rdev);
 	if (r == false || rdev->bios == NULL) {
 		DRM_ERROR("Unable to locate a BIOS ROM\n");
 		rdev->bios = NULL;

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