samsung-laptop: unregister ACPI video module for some well known laptops

On these laptops, the ACPI video is not functional, and very unlikely
to be fixed by the vendor. Note that intel_backlight works for some
of these laptops, and the backlight from samsung-laptop always work.

The good news is that newer laptops have functional ACPI video device
and won't end up growing this list.
Signed-off-by: Corentin Chary <corentincj@iksaif.net>
Signed-off-by: Matthew Garrett <mjg@redhat.com>

drivers/platform/x86/samsung-laptop.c

@@ -26,6 +26,9 @@
 #include <linux/seq_file.h>
 #include <linux/debugfs.h>
 #include <linux/ctype.h>
+#if (defined CONFIG_ACPI_VIDEO || defined CONFIG_ACPI_VIDEO_MODULE)
+#include <acpi/video.h>
+#endif
 
 /*
  * This driver is needed because a number of Samsung laptops do not hook
@@ -336,6 +339,7 @@ struct samsung_laptop {
 	struct work_struct kbd_led_work;
 
 	struct samsung_laptop_debug debug;
+	struct samsung_quirks *quirks;
 
 	bool handle_backlight;
 	bool has_stepping_quirk;
@@ -343,7 +347,15 @@ struct samsung_laptop {
 	char sdiag[64];
 };
 
+struct samsung_quirks {
+	bool broken_acpi_video;
+};
+
+static struct samsung_quirks samsung_unknown = {};
 
+static struct samsung_quirks samsung_broken_acpi_video = {
+	.broken_acpi_video = true,
+};
 
 static bool force;
 module_param(force, bool, 0);
@@ -1416,6 +1428,14 @@ static int __init samsung_platform_init(struct samsung_laptop *samsung)
 	return 0;
 }
 
+static struct samsung_quirks *quirks;
+
+static int __init samsung_dmi_matched(const struct dmi_system_id *d)
+{
+	quirks = d->driver_data;
+	return 0;
+}
+
 static struct dmi_system_id __initdata samsung_dmi_table[] = {
 	{
 		.matches = {
@@ -1445,6 +1465,47 @@ static struct dmi_system_id __initdata samsung_dmi_table[] = {
 			DMI_MATCH(DMI_CHASSIS_TYPE, "14"), /* Sub-Notebook */
 		},
 	},
+	/* Specific DMI ids for laptop with quirks */
+	{
+	 .callback = samsung_dmi_matched,
+	 .ident = "N150P",
+	 .matches = {
+		DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
+		DMI_MATCH(DMI_PRODUCT_NAME, "N150P"),
+		DMI_MATCH(DMI_BOARD_NAME, "N150P"),
+		},
+	 .driver_data = &samsung_broken_acpi_video,
+	},
+	{
+	 .callback = samsung_dmi_matched,
+	 .ident = "N145P/N250P/N260P",
+	 .matches = {
+		DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
+		DMI_MATCH(DMI_PRODUCT_NAME, "N145P/N250P/N260P"),
+		DMI_MATCH(DMI_BOARD_NAME, "N145P/N250P/N260P"),
+		},
+	 .driver_data = &samsung_broken_acpi_video,
+	},
+	{
+	 .callback = samsung_dmi_matched,
+	 .ident = "N150/N210/N220",
+	 .matches = {
+		DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
+		DMI_MATCH(DMI_PRODUCT_NAME, "N150/N210/N220"),
+		DMI_MATCH(DMI_BOARD_NAME, "N150/N210/N220"),
+		},
+	 .driver_data = &samsung_broken_acpi_video,
+	},
+	{
+	 .callback = samsung_dmi_matched,
+	 .ident = "NF110/NF210/NF310",
+	 .matches = {
+		DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
+		DMI_MATCH(DMI_PRODUCT_NAME, "NF110/NF210/NF310"),
+		DMI_MATCH(DMI_BOARD_NAME, "NF110/NF210/NF310"),
+		},
+	 .driver_data = &samsung_broken_acpi_video,
+	},
 	{ },
 };
 MODULE_DEVICE_TABLE(dmi, samsung_dmi_table);
@@ -1456,6 +1517,7 @@ static int __init samsung_init(void)
 	struct samsung_laptop *samsung;
 	int ret;
 
+	quirks = &samsung_unknown;
 	if (!force && !dmi_check_system(samsung_dmi_table))
 		return -ENODEV;
 
@@ -1465,12 +1527,21 @@ static int __init samsung_init(void)
 
 	mutex_init(&samsung->sabi_mutex);
 	samsung->handle_backlight = true;
+	samsung->quirks = quirks;
 
-#ifdef CONFIG_ACPI
+
+#if (defined CONFIG_ACPI_VIDEO || defined CONFIG_ACPI_VIDEO_MODULE)
 	/* Don't handle backlight here if the acpi video already handle it */
-	if (acpi_video_backlight_support())
-		samsung->handle_backlight = false;
+	if (acpi_video_backlight_support()) {
+		if (samsung->quirks->broken_acpi_video) {
+			pr_info("Disabling ACPI video driver\n");
+			acpi_video_unregister();
+		} else {
+			samsung->handle_backlight = false;
+		}
+	}
 #endif
+
 	ret = samsung_platform_init(samsung);
 	if (ret)
 		goto error_platform;
@@ -1481,7 +1552,8 @@ static int __init samsung_init(void)
 
 #ifdef CONFIG_ACPI
 	/* Only log that if we are really on a sabi platform */
-	if (acpi_video_backlight_support())
+	if (acpi_video_backlight_support() &&
+	    !samsung->quirks->broken_acpi_video)
 		pr_info("Backlight controlled by ACPI video driver\n");
 #endif