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author | Lukas Wunner <lukas@wunner.de> | 2018-01-24 19:35:45 +0100 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-02-22 15:42:26 +0100 |
commit | 598b21708ec09ad33cd66d162d2fea2dd66d9f64 (patch) | |
tree | ea6a8e827281504edb024c81f370e6bf4bd22bb6 /drivers/platform | |
parent | e7cedb56ae9a1c00b76df98d2adebb6208d2b71e (diff) | |
download | linux-stable-598b21708ec09ad33cd66d162d2fea2dd66d9f64.tar.gz linux-stable-598b21708ec09ad33cd66d162d2fea2dd66d9f64.tar.bz2 linux-stable-598b21708ec09ad33cd66d162d2fea2dd66d9f64.zip |
Revert "apple-gmux: lock iGP IO to protect from vgaarb changes"
commit d6fa7588fd7a8def4c747c0c574ce85d453e3788 upstream.
Commit 4eebd5a4e726 ("apple-gmux: lock iGP IO to protect from vgaarb
changes") amended this driver's ->probe hook to lock decoding of normal
(non-legacy) I/O space accesses to the integrated GPU on dual-GPU
MacBook Pros. The lock stays in place until the driver is unbound.
The change was made to work around an issue with the out-of-tree nvidia
graphics driver (available at http://www.nvidia.com/object/unix.html).
It contains the following sequence in nvidia/nv.c:
#if defined(CONFIG_VGA_ARB) && !defined(NVCPU_PPC64LE)
#if defined(VGA_DEFAULT_DEVICE)
vga_tryget(VGA_DEFAULT_DEVICE, VGA_RSRC_LEGACY_MASK);
#endif
vga_set_legacy_decoding(dev, VGA_RSRC_NONE);
#endif
This code was reported to cause deadlocks with VFIO already in 2013:
https://devtalk.nvidia.com/default/topic/545560
I've reported the issue to Nvidia developers once more in 2017:
https://www.spinics.net/lists/dri-devel/msg138754.html
On the MacBookPro10,1, this code apparently breaks backlight control
(which is handled by apple-gmux via an I/O region starting at 0x700),
as reported by Petri Hodju:
https://bugzilla.kernel.org/show_bug.cgi?id=86121
I tried to replicate Petri's observations on my MacBook9,1, which uses
the same Intel Ivy Bridge + Nvidia GeForce GT 650M architecture, to no
avail. On my machine apple-gmux' I/O region remains accessible even
with the nvidia driver loaded and commit 4eebd5a4e726 reverted.
Petri reported that apple-gmux becomes accessible again after a
suspend/resume cycle because the BIOS changed the VGA routing on the
root port to the Nvidia GPU. Perhaps this is a BIOS issue after all
that can be fixed with an update?
In any case, the change made by commit 4eebd5a4e726 has turned out to
cause two new issues:
* Wilfried Klaebe reports a deadlock when launching Xorg because it
opens /dev/vga_arbiter and calls vga_get(), but apple-gmux is holding
a lock on I/O space indefinitely. It looks like apple-gmux' current
behavior is an abuse of the vgaarb API as locks are not meant to be
held for longer periods:
https://bugzilla.kernel.org/show_bug.cgi?id=88861#c11
https://bugzilla.kernel.org/attachment.cgi?id=217541
* On dual GPU MacBook Pros introduced since 2013, the integrated GPU is
powergated on boot und thus becomes invisible to Linux unless a custom
EFI protocol is used to leave it powered on. (A patch exists but is
not in mainline yet due to several negative side effects.) On these
machines, locking I/O to the integrated GPU (as done by 4eebd5a4e726)
fails and backlight control is therefore broken:
https://bugzilla.kernel.org/show_bug.cgi?id=105051
So let's revert commit 4eebd5a4e726 please. Users experiencing the
issue with the proprietary nvidia driver can comment out the above-
quoted problematic code as a workaround (or try updating the BIOS).
Cc: Petri Hodju <petrihodju@yahoo.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Bruno Prémont <bonbons@linux-vserver.org>
Cc: Andy Ritger <aritger@nvidia.com>
Cc: Ronald Tschalär <ronald@innovation.ch>
Tested-by: Wilfried Klaebe <linux-kernel@lebenslange-mailadresse.de>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: stable@vger.kernel.org
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/platform')
-rw-r--r-- | drivers/platform/x86/apple-gmux.c | 48 |
1 files changed, 1 insertions, 47 deletions
diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c index 623d322447a2..7c4eb86c851e 100644 --- a/drivers/platform/x86/apple-gmux.c +++ b/drivers/platform/x86/apple-gmux.c @@ -24,7 +24,6 @@ #include <linux/delay.h> #include <linux/pci.h> #include <linux/vga_switcheroo.h> -#include <linux/vgaarb.h> #include <acpi/video.h> #include <asm/io.h> @@ -54,7 +53,6 @@ struct apple_gmux_data { bool indexed; struct mutex index_lock; - struct pci_dev *pdev; struct backlight_device *bdev; /* switcheroo data */ @@ -599,23 +597,6 @@ static int gmux_resume(struct device *dev) return 0; } -static struct pci_dev *gmux_get_io_pdev(void) -{ - struct pci_dev *pdev = NULL; - - while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_VGA << 8, pdev))) { - u16 cmd; - - pci_read_config_word(pdev, PCI_COMMAND, &cmd); - if (!(cmd & PCI_COMMAND_IO)) - continue; - - return pdev; - } - - return NULL; -} - static int is_thunderbolt(struct device *dev, void *data) { return to_pci_dev(dev)->is_thunderbolt; @@ -631,7 +612,6 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id) int ret = -ENXIO; acpi_status status; unsigned long long gpe; - struct pci_dev *pdev = NULL; if (apple_gmux_data) return -EBUSY; @@ -682,7 +662,7 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id) ver_minor = (version >> 16) & 0xff; ver_release = (version >> 8) & 0xff; } else { - pr_info("gmux device not present or IO disabled\n"); + pr_info("gmux device not present\n"); ret = -ENODEV; goto err_release; } @@ -690,23 +670,6 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id) pr_info("Found gmux version %d.%d.%d [%s]\n", ver_major, ver_minor, ver_release, (gmux_data->indexed ? "indexed" : "classic")); - /* - * Apple systems with gmux are EFI based and normally don't use - * VGA. In addition changing IO+MEM ownership between IGP and dGPU - * disables IO/MEM used for backlight control on some systems. - * Lock IO+MEM to GPU with active IO to prevent switch. - */ - pdev = gmux_get_io_pdev(); - if (pdev && vga_tryget(pdev, - VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM)) { - pr_err("IO+MEM vgaarb-locking for PCI:%s failed\n", - pci_name(pdev)); - ret = -EBUSY; - goto err_release; - } else if (pdev) - pr_info("locked IO for PCI:%s\n", pci_name(pdev)); - gmux_data->pdev = pdev; - memset(&props, 0, sizeof(props)); props.type = BACKLIGHT_PLATFORM; props.max_brightness = gmux_read32(gmux_data, GMUX_PORT_MAX_BRIGHTNESS); @@ -822,10 +785,6 @@ err_enable_gpe: err_notify: backlight_device_unregister(bdev); err_release: - if (gmux_data->pdev) - vga_put(gmux_data->pdev, - VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM); - pci_dev_put(pdev); release_region(gmux_data->iostart, gmux_data->iolen); err_free: kfree(gmux_data); @@ -845,11 +804,6 @@ static void gmux_remove(struct pnp_dev *pnp) &gmux_notify_handler); } - if (gmux_data->pdev) { - vga_put(gmux_data->pdev, - VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM); - pci_dev_put(gmux_data->pdev); - } backlight_device_unregister(gmux_data->bdev); release_region(gmux_data->iostart, gmux_data->iolen); |