From: Lukas Wunner <lukas@xxxxxxxxx>
[ Upstream commit 3916e3fd81021fb795bfbdb17f375b6b3685bced ]
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.
Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
Acked-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
[Jani: included notes in the commit message for posterity]
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
---
drivers/gpu/drm/i915/intel_lvds.c | 18 +++++++++++++++++-
1 file changed, 17 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
index c0bbf21..b7e80bf 100644
--- a/drivers/gpu/drm/i915/intel_lvds.c
+++ b/drivers/gpu/drm/i915/intel_lvds.c
@@ -809,12 +809,28 @@ static int intel_dual_link_lvds_callback(const struct dmi_system_id *id)
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 */
};
--
2.1.0
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