drm: allow loading an EDID as firmware to override broken monitor

Broken monitors and/or broken graphic boards may send erroneous or no
EDID data. This also applies to broken KVM devices that are unable to
correctly forward the EDID data of the connected monitor but invent
their own fantasy data.

This patch allows to specify an EDID data set to be used instead of
probing the monitor for it. It contains built-in data sets of frequently
used screen resolutions. In addition, a particular EDID data set may be
provided in the /lib/firmware directory and loaded via the firmware
interface. The name is passed to the kernel as module parameter of the
drm_kms_helper module either when loaded
  options drm_kms_helper edid_firmware=edid/1280x1024.bin
or as kernel commandline parameter
  drm_kms_helper.edid_firmware=edid/1280x1024.bin

It is also possible to restrict the usage of a specified EDID data set
to a particular connector. This is done by prepending the name of the
connector to the name of the EDID data set using the syntax
  edid_firmware=[<connector>:]<edid>
such as, for example,
  edid_firmware=DVI-I-1:edid/1920x1080.bin
in which case no other connector will be affected.

The built-in data sets are
Resolution    Name
--------------------------------
1024x768      edid/1024x768.bin
1280x1024     edid/1280x1024.bin
1680x1050     edid/1680x1050.bin
1920x1080     edid/1920x1080.bin

They are ignored, if a file with the same name is available in the
/lib/firmware directory.

The built-in EDID data sets are based on standard timings that may not
apply to a particular monitor and even crash it. Ideally, EDID data of
the connected monitor should be used. They may be obtained through the
drm/cardX/cardX-<connector>/edid entry in the /sys/devices PCI directory
of a correctly working graphics adapter.

It is even possible to specify the name of an EDID data set on-the-fly
via the /sys/module interface, e.g.
echo edid/myedid.bin >/sys/module/drm_kms_helper/parameters/edid_firmware
The new screen mode is considered when the related kernel function is
called for the first time after the change. Such calls are made when the
X server is started or when the display settings dialog is opened in an
already running X server.

Signed-off-by: Carsten Emde <C.Emde@osadl.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>

5 files changed, 272 insertions, 3 deletions

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 6b358d1dfb24..87ca18b82e15 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -32,6 +32,18 @@ config DRM_KMS_HELPER
         help
           FB and CRTC helpers for KMS drivers.
 
+config DRM_LOAD_EDID_FIRMWARE
+        bool "Allow to specify an EDID data set instead of probing for it"
+        depends on DRM_KMS_HELPER
+        help
+          Say Y here, if you want to use EDID data to be loaded from the
+          /lib/firmware directory or one of the provided built-in
+          data sets. This may be necessary, if the graphics adapter or
+          monitor are unable to provide appropriate EDID data. Since this
+          feature is provided as a workaround for broken hardware, the
+          default case is N. Details and instructions how to build your own
+          EDID data are given in Documentation/EDID/HOWTO.txt.
+
 config DRM_TTM
         tristate
         depends on DRM
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index 3b8be8939bb6..a858532806ae 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -19,6 +19,7 @@ drm-$(CONFIG_COMPAT) += drm_ioc32.o
 drm-usb-y   := drm_usb.o
 
 drm_kms_helper-y := drm_fb_helper.o drm_crtc_helper.o drm_dp_i2c_helper.o
+drm_kms_helper-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o
 
 obj-$(CONFIG_DRM_KMS_HELPER) += drm_kms_helper.o
 
diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c
index d9d66846c610..81118893264c 100644
--- a/drivers/gpu/drm/drm_crtc_helper.c
+++ b/drivers/gpu/drm/drm_crtc_helper.c
@@ -37,6 +37,7 @@
 #include "drm_fourcc.h"
 #include "drm_crtc_helper.h"
 #include "drm_fb_helper.h"
+#include "drm_edid.h"
 
 static bool drm_kms_helper_poll = true;
 module_param_named(poll, drm_kms_helper_poll, bool, 0600);
@@ -118,7 +119,12 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
                 goto prune;
         }
 
-        count = (*connector_funcs->get_modes)(connector);
+#ifdef CONFIG_DRM_LOAD_EDID_FIRMWARE
+        count = drm_load_edid_firmware(connector);
+        if (count == 0)
+#endif
+                count = (*connector_funcs->get_modes)(connector);
+
         if (count == 0 && connector->status == connector_status_connected)
                 count = drm_add_modes_noedid(connector, 1024, 768);
         if (count == 0)
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 7ee7be1e5ce6..7a1434aeffc4 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -149,8 +149,7 @@ EXPORT_SYMBOL(drm_edid_header_is_valid);
  * Sanity check the EDID block (base or extension).  Return 0 if the block
  * doesn't check out, or 1 if it's valid.
  */
-static bool
-drm_edid_block_valid(u8 *raw_edid)
+bool drm_edid_block_valid(u8 *raw_edid)
 {
         int i;
         u8 csum = 0;
@@ -203,6 +202,7 @@ bad:
         }
         return 0;
 }
+EXPORT_SYMBOL(drm_edid_block_valid);
 
 /**
  * drm_edid_is_valid - sanity check EDID data
diff --git a/drivers/gpu/drm/drm_edid_load.c b/drivers/gpu/drm/drm_edid_load.c
new file mode 100644
index 000000000000..da9acba2dd6c
--- /dev/null
+++ b/drivers/gpu/drm/drm_edid_load.c
@@ -0,0 +1,250 @@
+/*
+   drm_edid_load.c: use a built-in EDID data set or load it via the firmware
+                    interface
+
+   Copyright (C) 2012 Carsten Emde <C.Emde@osadl.org>
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License
+   as published by the Free Software Foundation; either version 2
+   of the License, or (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA.
+*/
+
+#include <linux/module.h>
+#include <linux/firmware.h>
+#include "drmP.h"
+#include "drm_crtc.h"
+#include "drm_crtc_helper.h"
+#include "drm_edid.h"
+
+static char edid_firmware[PATH_MAX];
+module_param_string(edid_firmware, edid_firmware, sizeof(edid_firmware), 0644);
+MODULE_PARM_DESC(edid_firmware, "Do not probe monitor, use specified EDID blob "
+        "from built-in data or /lib/firmware instead. ");
+
+#define GENERIC_EDIDS 4
+static char *generic_edid_name[GENERIC_EDIDS] = {
+        "edid/1024x768.bin",
+        "edid/1280x1024.bin",
+        "edid/1680x1050.bin",
+        "edid/1920x1080.bin",
+};
+
+static u8 generic_edid[GENERIC_EDIDS][128] = {
+        {
+        0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00,
+        0x31, 0xd8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        0x05, 0x16, 0x01, 0x03, 0x6d, 0x23, 0x1a, 0x78,
+        0xea, 0x5e, 0xc0, 0xa4, 0x59, 0x4a, 0x98, 0x25,
+        0x20, 0x50, 0x54, 0x00, 0x08, 0x00, 0x61, 0x40,
+        0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+        0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x64, 0x19,
+        0x00, 0x40, 0x41, 0x00, 0x26, 0x30, 0x08, 0x90,
+        0x36, 0x00, 0x63, 0x0a, 0x11, 0x00, 0x00, 0x18,
+        0x00, 0x00, 0x00, 0xff, 0x00, 0x4c, 0x69, 0x6e,
+        0x75, 0x78, 0x20, 0x23, 0x30, 0x0a, 0x20, 0x20,
+        0x20, 0x20, 0x00, 0x00, 0x00, 0xfd, 0x00, 0x3b,
+        0x3d, 0x2f, 0x31, 0x07, 0x00, 0x0a, 0x20, 0x20,
+        0x20, 0x20, 0x20, 0x20, 0x00, 0x00, 0x00, 0xfc,
+        0x00, 0x4c, 0x69, 0x6e, 0x75, 0x78, 0x20, 0x58,
+        0x47, 0x41, 0x0a, 0x20, 0x20, 0x20, 0x00, 0x55,
+        },
+        {
+        0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00,
+        0x31, 0xd8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        0x05, 0x16, 0x01, 0x03, 0x6d, 0x2c, 0x23, 0x78,
+        0xea, 0x5e, 0xc0, 0xa4, 0x59, 0x4a, 0x98, 0x25,
+        0x20, 0x50, 0x54, 0x00, 0x00, 0x00, 0x81, 0x80,
+        0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+        0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x30, 0x2a,
+        0x00, 0x98, 0x51, 0x00, 0x2a, 0x40, 0x30, 0x70,
+        0x13, 0x00, 0xbc, 0x63, 0x11, 0x00, 0x00, 0x1e,
+        0x00, 0x00, 0x00, 0xff, 0x00, 0x4c, 0x69, 0x6e,
+        0x75, 0x78, 0x20, 0x23, 0x30, 0x0a, 0x20, 0x20,
+        0x20, 0x20, 0x00, 0x00, 0x00, 0xfd, 0x00, 0x3b,
+        0x3d, 0x3e, 0x40, 0x0b, 0x00, 0x0a, 0x20, 0x20,
+        0x20, 0x20, 0x20, 0x20, 0x00, 0x00, 0x00, 0xfc,
+        0x00, 0x4c, 0x69, 0x6e, 0x75, 0x78, 0x20, 0x53,
+        0x58, 0x47, 0x41, 0x0a, 0x20, 0x20, 0x00, 0xa0,
+        },
+        {
+        0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00,
+        0x31, 0xd8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        0x05, 0x16, 0x01, 0x03, 0x6d, 0x2b, 0x1b, 0x78,
+        0xea, 0x5e, 0xc0, 0xa4, 0x59, 0x4a, 0x98, 0x25,
+        0x20, 0x50, 0x54, 0x00, 0x00, 0x00, 0xb3, 0x00,
+        0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+        0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x21, 0x39,
+        0x90, 0x30, 0x62, 0x1a, 0x27, 0x40, 0x68, 0xb0,
+        0x36, 0x00, 0xb5, 0x11, 0x11, 0x00, 0x00, 0x1e,
+        0x00, 0x00, 0x00, 0xff, 0x00, 0x4c, 0x69, 0x6e,
+        0x75, 0x78, 0x20, 0x23, 0x30, 0x0a, 0x20, 0x20,
+        0x20, 0x20, 0x00, 0x00, 0x00, 0xfd, 0x00, 0x3b,
+        0x3d, 0x40, 0x42, 0x0f, 0x00, 0x0a, 0x20, 0x20,
+        0x20, 0x20, 0x20, 0x20, 0x00, 0x00, 0x00, 0xfc,
+        0x00, 0x4c, 0x69, 0x6e, 0x75, 0x78, 0x20, 0x57,
+        0x53, 0x58, 0x47, 0x41, 0x0a, 0x20, 0x00, 0x26,
+        },
+        {
+        0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00,
+        0x31, 0xd8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        0x05, 0x16, 0x01, 0x03, 0x6d, 0x32, 0x1c, 0x78,
+        0xea, 0x5e, 0xc0, 0xa4, 0x59, 0x4a, 0x98, 0x25,
+        0x20, 0x50, 0x54, 0x00, 0x00, 0x00, 0xd1, 0xc0,
+        0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+        0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x02, 0x3a,
+        0x80, 0x18, 0x71, 0x38, 0x2d, 0x40, 0x58, 0x2c,
+        0x45, 0x00, 0xf4, 0x19, 0x11, 0x00, 0x00, 0x1e,
+        0x00, 0x00, 0x00, 0xff, 0x00, 0x4c, 0x69, 0x6e,
+        0x75, 0x78, 0x20, 0x23, 0x30, 0x0a, 0x20, 0x20,
+        0x20, 0x20, 0x00, 0x00, 0x00, 0xfd, 0x00, 0x3b,
+        0x3d, 0x42, 0x44, 0x0f, 0x00, 0x0a, 0x20, 0x20,
+        0x20, 0x20, 0x20, 0x20, 0x00, 0x00, 0x00, 0xfc,
+        0x00, 0x4c, 0x69, 0x6e, 0x75, 0x78, 0x20, 0x46,
+        0x48, 0x44, 0x0a, 0x20, 0x20, 0x20, 0x00, 0x05,
+        },
+};
+
+static int edid_load(struct drm_connector *connector, char *name,
+                     char *connector_name)
+{
+        const struct firmware *fw;
+        struct platform_device *pdev;
+        u8 *fwdata = NULL, *edid;
+        int fwsize, expected;
+        int builtin = 0, err = 0;
+        int i, valid_extensions = 0;
+
+        pdev = platform_device_register_simple(connector_name, -1, NULL, 0);
+        if (IS_ERR(pdev)) {
+                DRM_ERROR("Failed to register EDID firmware platform device "
+                    "for connector \"%s\"\n", connector_name);
+                err = -EINVAL;
+                goto out;
+        }
+
+        err = request_firmware(&fw, name, &pdev->dev);
+        platform_device_unregister(pdev);
+
+        if (err) {
+                i = 0;
+                while (i < GENERIC_EDIDS && strcmp(name, generic_edid_name[i]))
+                        i++;
+                if (i < GENERIC_EDIDS) {
+                        err = 0;
+                        builtin = 1;
+                        fwdata = generic_edid[i];
+                        fwsize = sizeof(generic_edid[i]);
+                }
+        }
+
+        if (err) {
+                DRM_ERROR("Requesting EDID firmware \"%s\" failed (err=%d)\n",
+                    name, err);
+                goto out;
+        }
+
+        if (fwdata == NULL) {
+                fwdata = (u8 *) fw->data;
+                fwsize = fw->size;
+        }
+
+        expected = (fwdata[0x7e] + 1) * EDID_LENGTH;
+        if (expected != fwsize) {
+                DRM_ERROR("Size of EDID firmware \"%s\" is invalid "
+                    "(expected %d, got %d)\n", name, expected, (int) fwsize);
+                err = -EINVAL;
+                goto relfw_out;
+        }
+
+        edid = kmalloc(fwsize, GFP_KERNEL);
+        if (edid == NULL) {
+                err = -ENOMEM;
+                goto relfw_out;
+        }
+        memcpy(edid, fwdata, fwsize);
+
+        if (!drm_edid_block_valid(edid)) {
+                DRM_ERROR("Base block of EDID firmware \"%s\" is invalid ",
+                    name);
+                kfree(edid);
+                err = -EINVAL;
+                goto relfw_out;
+        }
+
+        for (i = 1; i <= edid[0x7e]; i++) {
+                if (i != valid_extensions + 1)
+                        memcpy(edid + (valid_extensions + 1) * EDID_LENGTH,
+                            edid + i * EDID_LENGTH, EDID_LENGTH);
+                if (drm_edid_block_valid(edid + i * EDID_LENGTH))
+                        valid_extensions++;
+        }
+
+        if (valid_extensions != edid[0x7e]) {
+                edid[EDID_LENGTH-1] += edid[0x7e] - valid_extensions;
+                DRM_INFO("Found %d valid extensions instead of %d in EDID data "
+                    "\"%s\" for connector \"%s\"\n", valid_extensions,
+                    edid[0x7e], name, connector_name);
+                edid[0x7e] = valid_extensions;
+                edid = krealloc(edid, (valid_extensions + 1) * EDID_LENGTH,
+                    GFP_KERNEL);
+                if (edid == NULL) {
+                        err = -ENOMEM;
+                        goto relfw_out;
+                }
+        }
+
+        connector->display_info.raw_edid = edid;
+        DRM_INFO("Got %s EDID base block and %d extension%s from "
+            "\"%s\" for connector \"%s\"\n", builtin ? "built-in" :
+            "external", valid_extensions, valid_extensions == 1 ? "" : "s",
+            name, connector_name);
+
+relfw_out:
+        release_firmware(fw);
+
+out:
+        return err;
+}
+
+int drm_load_edid_firmware(struct drm_connector *connector)
+{
+        char *connector_name = drm_get_connector_name(connector);
+        char *edidname = edid_firmware, *last, *colon;
+        int ret = 0;
+
+        if (*edidname == '\0')
+                return ret;
+
+        colon = strchr(edidname, ':');
+        if (colon != NULL) {
+                if (strncmp(connector_name, edidname, colon - edidname))
+                        return ret;
+                edidname = colon + 1;
+                if (*edidname == '\0')
+                        return ret;
+        }
+
+        last = edidname + strlen(edidname) - 1;
+        if (*last == '\n')
+                *last = '\0';
+
+        ret = edid_load(connector, edidname, connector_name);
+        if (ret)
+                return 0;
+
+        drm_mode_connector_update_edid_property(connector,
+            (struct edid *) connector->display_info.raw_edid);
+
+        return drm_add_edid_modes(connector, (struct edid *)
+            connector->display_info.raw_edid);
+}