Patch "drm/i915: Add missing MacBook Pro models with dual channel LVDS" has been added to the 3.14-stable tree

This is a note to let you know that I've just added the patch titled

drm/i915: Add missing MacBook Pro models with dual channel LVDS

to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
drm-i915-add-missing-macbook-pro-models-with-dual-channel-lvds.patch
and it can be found in the queue-3.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Lukas Wunner <[email protected]>
Date: Mon, 4 May 2015 15:06:49 +0200
Subject: drm/i915: Add missing MacBook Pro models with dual channel LVDS

From: Lukas Wunner <[email protected]>

commit 3916e3fd81021fb795bfbdb17f375b6b3685bced upstream.

Single channel LVDS maxes out at 112 MHz. The 15" pre-retina models shipped with 1440x900 (106 MHz) by default or 1680x1050 (119 MHz) as a BTO option, both versions used dual channel LVDS even though the smaller one would have fit into a single channel.

Notes:
Bug report showing that the MacBookPro8,2 with 1440x900 uses dual channel LVDS (this lead to it being hardcoded in intel_lvds.c by Daniel Vetter with commit 618563e3945b9d0864154bab3c607865b557cecc):

    https://bugzilla.kernel.org/show_bug.cgi?id=42842

If i915.lvds_channel_mode=2 is missing even though the machine needs it, every other vertical line is white and consequently, only the left half of the screen is visible (verified by myself on a MacBookPro9,1).

Forum posting concerning a MacBookPro6,2 with 1440x900, author is using i915.lvds_channel_mode=2 on the kernel command line, proving that the machine uses dual channels:

    https://bbs.archlinux.org/viewtopic.php?id=185770

Chi Mei N154C6-L04 with 1440x900 is a replacement panel for all MacBook Pro "A1286" models, and that model number encompasses the MacBookPro6,2 / 8,2 / 9,1. Page 17 of the panel's datasheet shows it's driven with dual channel LVDS:

    http://www.ebay.com/itm/-/400690878560
    http://www.everymac.com/ultimate-mac-lookup/?search_keywords=A1286
    http://www.taopanel.com/chimei/datasheet/N154C6-L04.pdf

Those three 15" models, MacBookPro6,2 / 8,2 / 9,1, are the only ones with i915 graphics and dual channel LVDS, so that list should be complete. And the 8,2 is already in intel_lvds.c.

Possible motivation to use dual channel LVDS even on the 1440x900
models: Reduce the number of different parts, i.e. use identical logic boards and display cabling on both versions and the only differing component is the panel.

---
 drivers/gpu/drm/i915/intel_lvds.c |   18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

@@ -815,12 +815,28 @@ static int intel_dual_link_lvds_callback
 static const struct dmi_system_id intel_dual_link_lvds[] = {
 	{
 		.callback = intel_dual_link_lvds_callback,
-		.ident = "Apple MacBook Pro (Core i5/i7 Series)",
+		.ident = "Apple MacBook Pro 15\" (2010)",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro6,2"),
+		},
+	},
+	{
+		.callback = intel_dual_link_lvds_callback,
+		.ident = "Apple MacBook Pro 15\" (2011)",
 		.matches = {
 			DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
 			DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro8,2"),
 		},
 	},
+	{
+		.callback = intel_dual_link_lvds_callback,
+		.ident = "Apple MacBook Pro 15\" (2012)",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro9,1"),
+		},
+	},
 	{ }	/* terminating entry */
 };
 

Patches currently in stable-queue which might be from [email protected] are

queue-3.14/drm-i915-add-missing-macbook-pro-models-with-dual-channel-lvds.patch