ACPI / video: Add a parameter to not register the backlight sysfs interface

On some systems acpi-video backlight is broken in the sense that it cannot
control the brightness of the backlight, but it must still be called on
resume to power-up the backlight after resume.

This commit allows these systems to work by going through all the usual
backlight control moves, while not registering a sysfs backlight
interface.

This commit also adds a quirk enabling this parameter on Toshiba Portege
R830 systems which are known to be affected by this.

I wish there was a better way to deal with this, but we've been unable to
find one.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=21012
Link: https://bugs.freedesktop.org/show_bug.cgi?id=82634
Reported-and-tested-by: Sylvain Pasche <sylvain.pasche@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index 518f0e1d274dc9c6d36c15045421b56cfbcf642c..3bc4c68d8bd010f165a6c11a23ec61dc88d1ddfc 100644 (file)
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -92,6 +92,9 @@ static int use_native_backlight_param = NATIVE_BACKLIGHT_NOT_SET;
 module_param_named(use_native_backlight, use_native_backlight_param, int, 0444);
 static int use_native_backlight_dmi = NATIVE_BACKLIGHT_NOT_SET;
 
+static int disable_backlight_sysfs_if = -1;
+module_param(disable_backlight_sysfs_if, int, 0444);
+
 static int register_count;
 static struct mutex video_list_lock;
 static struct list_head video_bus_head;
@@ -431,6 +434,14 @@ static int __init video_enable_native_backlight(const struct dmi_system_id *d)
        return 0;
 }
 
+static int __init video_disable_backlight_sysfs_if(
+       const struct dmi_system_id *d)
+{
+       if (disable_backlight_sysfs_if == -1)
+               disable_backlight_sysfs_if = 1;
+       return 0;
+}
+
 static struct dmi_system_id video_dmi_table[] __initdata = {
        /*
         * Broken _BQC workaround http://bugzilla.kernel.org/show_bug.cgi?id=13121
@@ -592,6 +603,23 @@ static struct dmi_system_id video_dmi_table[] __initdata = {
                DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro12,1"),
                },
        },
+
+       /*
+        * Some machines have a broken acpi-video interface for brightness
+        * control, but still need an acpi_video_device_lcd_set_level() call
+        * on resume to turn the backlight power on.  We Enable backlight
+        * control on these systems, but do not register a backlight sysfs
+        * as brightness control does not work.
+        */
+       {
+        /* https://bugs.freedesktop.org/show_bug.cgi?id=82634 */
+        .callback = video_disable_backlight_sysfs_if,
+        .ident = "Toshiba Portege R830",
+        .matches = {
+               DMI_MATCH(DMI_SYS_VENDOR, "TOSHIBA"),
+               DMI_MATCH(DMI_PRODUCT_NAME, "PORTEGE R830"),
+               },
+       },
        {}
 };
 
@@ -1391,7 +1419,7 @@ acpi_video_switch_brightness(struct work_struct *work)
        int result = -EINVAL;
 
        /* no warning message if acpi_backlight=vendor or a quirk is used */
-       if (!acpi_video_verify_backlight_support())
+       if (!device->backlight)
                return;
 
        if (!device->brightness)
@@ -1666,8 +1694,9 @@ static int acpi_video_resume(struct notifier_block *nb,
 
        for (i = 0; i < video->attached_count; i++) {
                video_device = video->attached_array[i].bind_info;
-               if (video_device && video_device->backlight)
-                       acpi_video_set_brightness(video_device->backlight);
+               if (video_device && video_device->brightness)
+                       acpi_video_device_lcd_set_level(video_device,
+                                       video_device->brightness->curr);
        }
 
        return NOTIFY_OK;
@@ -1716,6 +1745,10 @@ static void acpi_video_dev_register_backlight(struct acpi_video_device *device)
        result = acpi_video_init_brightness(device);
        if (result)
                return;
+
+       if (disable_backlight_sysfs_if > 0)
+               return;
+
        name = kasprintf(GFP_KERNEL, "acpi_video%d", count);
        if (!name)
                return;
@@ -1738,8 +1771,10 @@ static void acpi_video_dev_register_backlight(struct acpi_video_device *device)
                                                      &acpi_backlight_ops,
                                                      &props);
        kfree(name);
-       if (IS_ERR(device->backlight))
+       if (IS_ERR(device->backlight)) {
+               device->backlight = NULL;
                return;
+       }
 
        /*
         * Save current brightness level in case we have to restore it