From 98b3a3402eb6e38c3bf5dd4281e60e1f186f0041 Mon Sep 17 00:00:00 2001 From: Lukas Wunner Date: Mon, 11 Jan 2016 20:09:20 +0100 Subject: [PATCH] drm/nouveau: Defer probe if gmux is present but its driver isn't gmux is a microcontroller built into dual GPU MacBook Pros. On pre-retina MBPs, if we're the inactive GPU, we need apple-gmux to temporarily switch DDC so that we can probe the panel's EDID. The checks for CONFIG_VGA_ARB and CONFIG_VGA_SWITCHEROO are necessary because if either of them is disabled but gmux is present, the driver would never load, even if we're the active GPU. (vga_default_device() would evaluate to NULL and vga_switcheroo_handler_flags() would evaluate to 0.) Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=88861 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=61115 Tested-by: Lukas Wunner [MBP 9,1 2012 intel IVB + nvidia GK107 pre-retina 15"] Signed-off-by: Lukas Wunner Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/d9542ca5041178165d3ff286c90cc99634f7d2ce.1452525860.git.lukas@wunner.de --- drivers/gpu/drm/nouveau/nouveau_drm.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c index 2f2f252e3fb6..bb8498c9b13e 100644 --- a/drivers/gpu/drm/nouveau/nouveau_drm.c +++ b/drivers/gpu/drm/nouveau/nouveau_drm.c @@ -22,11 +22,13 @@ * Authors: Ben Skeggs */ +#include #include #include #include #include #include +#include #include #include "drmP.h" @@ -312,6 +314,15 @@ static int nouveau_drm_probe(struct pci_dev *pdev, bool boot = false; int ret; + /* + * apple-gmux is needed on dual GPU MacBook Pro + * to probe the panel if we're the inactive GPU. + */ + if (IS_ENABLED(CONFIG_VGA_ARB) && IS_ENABLED(CONFIG_VGA_SWITCHEROO) && + apple_gmux_present() && pdev != vga_default_device() && + !vga_switcheroo_handler_flags()) + return -EPROBE_DEFER; + /* remove conflicting drivers (vesafb, efifb etc) */ aper = alloc_apertures(3); if (!aper) -- 2.20.1