radeon: Firmware is required for DRM and KMS on R600 onward

radeon requires firmware/microcode for the GPU in all chips, but for
newer chips (apparently R600 'Evergreen' onward) it also expects
firmware for the memory controller and other sub-blocks.

radeon attempts to gracefully fall back and disable some features if
the firmware is not available, but becomes unstable - the framebuffer
and/or system memory may be corrupted, or the display may stay black.

Therefore, perform a basic check for the existence of
/lib/firmware/radeon when a device is probed, and abort if it is
missing, except for the pre-R600 case.

Gbp-Pq: Topic bugfix/all
Gbp-Pq: Name radeon-firmware-is-required-for-drm-and-kms-on-r600-onward.patch

diff --git a/drivers/gpu/drm/radeon/radeon_drv.c b/drivers/gpu/drm/radeon/radeon_drv.c
index 30bd4a6a9d466e11755bf95cee6929473ae65adf..1f92c549b496531daa4b09ffd692ac86117a8bd1 100644 (file)
--- a/drivers/gpu/drm/radeon/radeon_drv.c
+++ b/drivers/gpu/drm/radeon/radeon_drv.c
@@ -43,6 +43,8 @@
 
 #include "drm_crtc_helper.h"
 #include "radeon_kfd.h"
+#include <linux/namei.h>
+#include <linux/path.h>
 
 /*
  * KMS wrapper.
@@ -310,6 +312,29 @@ static struct drm_driver kms_driver;
 
 bool radeon_device_is_virtual(void);
 
+/* Test that /lib/firmware/radeon is a directory (or symlink to a
+ * directory).  We could try to match the udev search path, but let's
+ * assume people take the easy route and install
+ * firmware-linux-nonfree.
+ */
+static bool radeon_firmware_installed(void)
+{
+#if IS_BUILTIN(CONFIG_DRM_RADEON)
+       /* It may be too early to tell.  Assume it's there. */
+       return true;
+#else
+       struct path path;
+
+       if (kern_path("/lib/firmware/radeon", LOOKUP_DIRECTORY | LOOKUP_FOLLOW,
+                     &path) == 0) {
+               path_put(&path);
+               return true;
+       }
+
+       return false;
+#endif
+}
+
 static int radeon_kick_out_firmware_fb(struct pci_dev *pdev)
 {
        struct apertures_struct *ap;
@@ -347,6 +372,12 @@ static int radeon_pci_probe(struct pci_dev *pdev,
        if (vga_switcheroo_client_probe_defer(pdev))
                return -EPROBE_DEFER;
 
+       if ((ent->driver_data & RADEON_FAMILY_MASK) >= CHIP_R600 &&
+           !radeon_firmware_installed()) {
+               DRM_ERROR("radeon kernel modesetting for R600 or later requires firmware-amd-graphics.\n");
+               return -ENODEV;
+       }
+
        /* Get rid of things like offb */
        ret = radeon_kick_out_firmware_fb(pdev);
        if (ret)