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drm/nouveau: Defer probe if gmux is present but its driver isn't

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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 <lukas@wunner.de>
    [MBP  9,1 2012  intel IVB + nvidia GK107  pre-retina  15"]
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/d9542ca5041178165d3ff286c90cc99634f7d2ce.1452525860.git.lukas@wunner.de
This commit is contained in:
Lukas Wunner 2016-01-11 20:09:20 +01:00 committed by Daniel Vetter
parent 704ab614ec
commit 98b3a3402e
1 changed files with 11 additions and 0 deletions
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11
drivers/gpu/drm/nouveau/nouveau_drm.c
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@ -22,11 +22,13 @@
* Authors: Ben Skeggs
*/
#include <linux/apple-gmux.h>
#include <linux/console.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/pm_runtime.h>
#include <linux/vgaarb.h>
#include <linux/vga_switcheroo.h>
#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)