drm/i915/opregion: let user specify override VBT via firmware load

Sometimes it would be most enlightening to debug systems by replacing
the VBT to be used. For example, in the referenced bug the BIOS provides
different VBT depending on the boot mode (UEFI vs. legacy). It would be
interesting to try the failing boot mode with the VBT from the working
boot, and see if that makes a difference.

Add a module parameter to load the VBT using the firmware loader, not
unlike the EDID firmware mechanism.

As a starting point for experimenting, one can pick up the BIOS provided
VBT from /sys/kernel/debug/dri/0/i915_opregion/i915_vbt.

v2: clarify firmware load return value check (Bob)

v3: kfree the loaded firmware blob

References: https://bugs.freedesktop.org/show_bug.cgi?id=97822#c83
Reviewed-by: Bob Paauwe <bob.j.paauwe@intel.com>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170817115209.25912-1-jani.nikula@intel.com

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 6c25c8520c872a7e9e374914b7d76e381dc75ca3..3ee4fd2a9b41c32e20a57c38c85307d746446681 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -646,6 +646,7 @@ struct intel_opregion {
        u32 swsci_sbcb_sub_functions;
        struct opregion_asle *asle;
        void *rvda;
+       void *vbt_firmware;
        const void *vbt;
        u32 vbt_size;
        u32 *lid_state;

diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index 14e2c2e57f96a53f2fdddd8ecf897c3d28a4ddce..8ab003dca11318469fc13a169a77758f9af30d86 100644 (file)
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -118,6 +118,10 @@ MODULE_PARM_DESC(vbt_sdvo_panel_type,
 module_param_named_unsafe(reset, i915.reset, int, 0600);
 MODULE_PARM_DESC(reset, "Attempt GPU resets (0=disabled, 1=full gpu reset, 2=engine reset [default])");
 
+module_param_named_unsafe(vbt_firmware, i915.vbt_firmware, charp, 0400);
+MODULE_PARM_DESC(vbt_firmware,
+                "Load VBT from specified file under /lib/firmware");
+
 #if IS_ENABLED(CONFIG_DRM_I915_CAPTURE_ERROR)
 module_param_named(error_capture, i915.error_capture, bool, 0600);
 MODULE_PARM_DESC(error_capture,

diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
index febbfdbd30bdb179ec310af6e5c7c1a54944d4db..ac844709c97e78a13bbe2334ca813efa80616678 100644 (file)
--- a/drivers/gpu/drm/i915/i915_params.h
+++ b/drivers/gpu/drm/i915/i915_params.h
@@ -28,6 +28,7 @@
 #include <linux/cache.h> /* for __read_mostly */
 
 #define I915_PARAMS_FOR_EACH(func) \
+       func(char *, vbt_firmware); \
        func(int, modeset); \
        func(int, panel_ignore_lid); \
        func(int, semaphores); \

diff --git a/drivers/gpu/drm/i915/intel_opregion.c b/drivers/gpu/drm/i915/intel_opregion.c
index 2bd03001cc709fbd278af5c3a94a7d6eb21654f2..98154efcb2f41f7f9f70206dca840c3b5dfde244 100644 (file)
--- a/drivers/gpu/drm/i915/intel_opregion.c
+++ b/drivers/gpu/drm/i915/intel_opregion.c
@@ -27,6 +27,7 @@
 
 #include <linux/acpi.h>
 #include <linux/dmi.h>
+#include <linux/firmware.h>
 #include <acpi/video.h>
 
 #include <drm/drmP.h>
@@ -829,6 +830,10 @@ void intel_opregion_unregister(struct drm_i915_private *dev_priv)
                memunmap(opregion->rvda);
                opregion->rvda = NULL;
        }
+       if (opregion->vbt_firmware) {
+               kfree(opregion->vbt_firmware);
+               opregion->vbt_firmware = NULL;
+       }
        opregion->header = NULL;
        opregion->acpi = NULL;
        opregion->swsci = NULL;
@@ -912,6 +917,43 @@ static const struct dmi_system_id intel_no_opregion_vbt[] = {
        { }
 };
 
+static int intel_load_vbt_firmware(struct drm_i915_private *dev_priv)
+{
+       struct intel_opregion *opregion = &dev_priv->opregion;
+       const struct firmware *fw = NULL;
+       const char *name = i915.vbt_firmware;
+       int ret;
+
+       if (!name || !*name)
+               return -ENOENT;
+
+       ret = request_firmware(&fw, name, &dev_priv->drm.pdev->dev);
+       if (ret) {
+               DRM_ERROR("Requesting VBT firmware \"%s\" failed (%d)\n",
+                         name, ret);
+               return ret;
+       }
+
+       if (intel_bios_is_valid_vbt(fw->data, fw->size)) {
+               opregion->vbt_firmware = kmemdup(fw->data, fw->size, GFP_KERNEL);
+               if (opregion->vbt_firmware) {
+                       DRM_DEBUG_KMS("Found valid VBT firmware \"%s\"\n", name);
+                       opregion->vbt = opregion->vbt_firmware;
+                       opregion->vbt_size = fw->size;
+                       ret = 0;
+               } else {
+                       ret = -ENOMEM;
+               }
+       } else {
+               DRM_DEBUG_KMS("Invalid VBT firmware \"%s\"\n", name);
+               ret = -EINVAL;
+       }
+
+       release_firmware(fw);
+
+       return ret;
+}
+
 int intel_opregion_setup(struct drm_i915_private *dev_priv)
 {
        struct intel_opregion *opregion = &dev_priv->opregion;
@@ -974,6 +1016,9 @@ int intel_opregion_setup(struct drm_i915_private *dev_priv)
        if (mboxes & MBOX_ASLE_EXT)
                DRM_DEBUG_DRIVER("ASLE extension supported\n");
 
+       if (intel_load_vbt_firmware(dev_priv) == 0)
+               goto out;
+
        if (dmi_check_system(intel_no_opregion_vbt))
                goto out;