From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x224dXzp2TEO0bZM2+ftpsa2gMDa3WyxEnh3Fo1+7Ihs7YFxSpm9LMqI2wLfIQI/81vIZrgAy ARC-Seal: i=1; a=rsa-sha256; t=1519218151; cv=none; d=google.com; s=arc-20160816; b=o7I5AwhGOKcuK646+cecSJikyYd1CtKeDsvVXVM+MWWsV5IuJq/IWhJlrIQ2Pdz6Vd eQhtoWU1hqJv2+ipkBpgVAIZze1wbY5pH2GLWlXzueTEs7AjY0sjDxNJRPKqSDyoPPh7 FIuwT7LW7Qtv09Ri41yIpEaxs/zXyakMAU6PO6MpUpJeIg24fdBdN3+RxJCHsrW9Hm7D 4SqPzMKpTNezoaGXV5v72w4a1fGzdHpl7L4TNQ05g7ivLwkZ7adW6hUxO7Zt5alEpUHx KE/YBmGUcgjqByhlbU7mcDRDQEGDdifuAV/tsQzritQkcq+u0ezNsibqUjVr1AIkWggX EH7Q== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=kiXUPhMIidnYg2NkcZrAzbJUXpNqY9l7C1bPaBZouAo=; b=TsWxgLP1SCdsv2lnD12Tnmc4oWfo0Ebz0k51DieQY8MYZmlHEVIJ9QUJ4vFvQL9bHG JuvRtbM6Z3QjVhOEQ1/zViae/Tr37VMzgm2E7Zpmm+5w2EXeVeD6vThEJz2xz9wISOMQ tmDxYv+EGPJzzwi1Z9C2/h5k+RKs1Q1XXw/UNoSDmYgL0cbd7v7ng7WhqlDaBl1LjkWa z8wPOT8YDEie3m5ghYtHrFUf3HIIDJmqrYitL3LuIM7QQwLsk9lVqNHbqbIeS3xO2IKz 6i4I4Rwg5+izfSf5DjciFpTk8AdetXg63Ljd/Wk72W+JkGZv3cXX2fKaECVC43UjdKfx Sk8A== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Petri Hodju , Bjorn Helgaas , =?UTF-8?q?Bruno=20Pr=C3=A9mont?= , Andy Ritger , =?UTF-8?q?Ronald=20Tschal=C3=A4r?= , Wilfried Klaebe , Lukas Wunner , "Darren Hart (VMware)" Subject: [PATCH 4.14 104/167] Revert "apple-gmux: lock iGP IO to protect from vgaarb changes" Date: Wed, 21 Feb 2018 13:48:35 +0100 Message-Id: <20180221124530.053661678@linuxfoundation.org> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180221124524.639039577@linuxfoundation.org> References: <20180221124524.639039577@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1593015691967203234?= X-GMAIL-MSGID: =?utf-8?q?1593015691967203234?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Lukas Wunner 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 Cc: Bjorn Helgaas Cc: Bruno Prémont Cc: Andy Ritger Cc: Ronald Tschalär Tested-by: Wilfried Klaebe Signed-off-by: Lukas Wunner Cc: stable@vger.kernel.org Signed-off-by: Darren Hart (VMware) Signed-off-by: Greg Kroah-Hartman --- drivers/platform/x86/apple-gmux.c | 48 -------------------------------------- 1 file changed, 1 insertion(+), 47 deletions(-) --- a/drivers/platform/x86/apple-gmux.c +++ b/drivers/platform/x86/apple-gmux.c @@ -24,7 +24,6 @@ #include #include #include -#include #include #include @@ -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 *de 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 *pn 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 *pn 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 *pn 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 * &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);