Message-Id: <20190212220230.1568-1-lyude@redhat.com>
Date:   Tue, 12 Feb 2019 17:02:30 -0500
From:   Lyude Paul <lyude@...hat.com>
To:     linux-pci@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     nouveau@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        Karol Herbst <kherbst@...hat.com>,
        Ben Skeggs <skeggsb@...il.com>, stable@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] pci/quirks: Add quirk to reset nvgpu at boot for the Lenovo ThinkPad P50

On a very specific subset of ThinkPad P50 SKUs, particularly ones that
come with a Quadro M1000M chip instead of the M2000M variant, the BIOS
seems to have a very nasty habit of not always resetting the secondary
Nvidia GPU between full reboots if the laptop is configured in Hybrid
Graphics mode. The reason for this happening is unknown, but the
following steps and possibly a good bit of patience will reproduce the
issue:

1. Boot up the laptop normally in Hybrid graphics mode
2. Make sure nouveau is loaded and that the GPU is awake
2. Allow the nvidia GPU to runtime suspend itself after being idle
3. Reboot the machine, the more sudden the better (e.g sysrq-b may help)
4. If nouveau loads up properly, reboot the machine again and go back to
step 2 until you reproduce the issue

This results in some very strange behavior: the GPU will
quite literally be left in exactly the same state it was in when the
previously booted kernel started the reboot. This has all sorts of bad
sideaffects: for starters, this completely breaks nouveau starting with a
mysterious EVO channel failure that happens well before we've actually
used the EVO channel for anything:

nouveau 0000:01:00.0: disp: chid 0 mthd 0000 data 00000400 00001000
00000002

Later on, this causes us to timeout trying to bring up the GR ctx:

------------[ cut here ]------------
nouveau 0000:01:00.0: timeout
WARNING: CPU: 0 PID: 12 at
drivers/gpu/drm/nouveau/nvkm/engine/gr/ctxgf100.c:1547
gf100_grctx_generate+0x7b2/0x850 [nouveau]
Modules linked in: nouveau mxm_wmi i915 crc32c_intel ttm i2c_algo_bit
serio_raw drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops
xhci_pci drm xhci_hcd i2c_core wmi video
CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.0.0-rc5Lyude-Test+ #29
Hardware name: LENOVO 20EQS64N0B/20EQS64N0B, BIOS N1EET82W (1.55 )
12/18/2018
Workqueue: events_long drm_dp_mst_link_probe_work [drm_kms_helper]
RIP: 0010:gf100_grctx_generate+0x7b2/0x850 [nouveau]
Code: 85 d2 75 04 48 8b 57 10 48 89 95 28 ff ff ff e8 b4 37 0e e1 48 8b
95 28 ff ff ff 48 c7 c7 b1 97 57 a0 48 89 c6 e8 5a 38 c0 e0 <0f> 0b e9
b9 fd ff ff 48 8b 85 60 ff ff ff 48 8b 40 10 48 8b 78 10
RSP: 0018:ffffc900000b77f0 EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffff888871af8000 RCX: 0000000000000000
RDX: ffff88887f41dfe0 RSI: ffff88887f415698 RDI: ffff88887f415698
RBP: ffffc900000b78c8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff888872118000
R13: 0000000000000000 R14: ffffffffa0551420 R15: ffffc900000b7818
FS:  0000000000000000(0000) GS:ffff88887f400000(0000)
knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005644d0556ca8 CR3: 0000000002214006 CR4: 00000000003606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 gf100_gr_init_ctxctl+0x27b/0x2d0 [nouveau]
 gf100_gr_init+0x5bd/0x5e0 [nouveau]
 gf100_gr_init_+0x61/0x70 [nouveau]
 nvkm_gr_init+0x1d/0x20 [nouveau]
 nvkm_engine_init+0xcb/0x210 [nouveau]
 nvkm_subdev_init+0xd6/0x230 [nouveau]
 nvkm_engine_ref.part.0+0x52/0x70 [nouveau]
 nvkm_engine_ref+0x13/0x20 [nouveau]
 nvkm_ioctl_new+0x12c/0x260 [nouveau]
 ? nvkm_fifo_chan_child_del+0xa0/0xa0 [nouveau]
 ? gf100_gr_dtor+0xe0/0xe0 [nouveau]
 nvkm_ioctl+0xe2/0x180 [nouveau]
 nvkm_client_ioctl+0x12/0x20 [nouveau]
 nvif_object_ioctl+0x47/0x50 [nouveau]
 nvif_object_init+0xc8/0x120 [nouveau]
 nvc0_fbcon_accel_init+0x5c/0x960 [nouveau]
 nouveau_fbcon_create+0x5a5/0x5d0 [nouveau]
 ? drm_setup_crtcs+0x27b/0xcb0 [drm_kms_helper]
 ? __lock_is_held+0x5e/0xa0
 __drm_fb_helper_initial_config_and_unlock+0x27c/0x520 [drm_kms_helper]
 drm_fb_helper_hotplug_event.part.29+0xae/0xc0 [drm_kms_helper]
 drm_fb_helper_hotplug_event+0x1c/0x30 [drm_kms_helper]
 nouveau_fbcon_output_poll_changed+0xb8/0x110 [nouveau]
 drm_kms_helper_hotplug_event+0x2a/0x40 [drm_kms_helper]
 drm_dp_send_link_address+0x176/0x1c0 [drm_kms_helper]
 drm_dp_check_and_send_link_address+0xa0/0xb0 [drm_kms_helper]
 drm_dp_mst_link_probe_work+0xa4/0xc0 [drm_kms_helper]
 process_one_work+0x22f/0x5c0
 worker_thread+0x44/0x3a0
 kthread+0x12b/0x150
 ? wq_pool_ids_show+0x140/0x140
 ? kthread_create_on_node+0x60/0x60
 ret_from_fork+0x3a/0x50
irq event stamp: 22490
hardirqs last  enabled at (22489): [<ffffffff8113281d>]
console_unlock+0x44d/0x5f0
hardirqs last disabled at (22490): [<ffffffff81001c03>]
trace_hardirqs_off_thunk+0x1a/0x1c
softirqs last  enabled at (22486): [<ffffffff81c00330>]
__do_softirq+0x330/0x44d
softirqs last disabled at (22479): [<ffffffff810c3105>]
irq_exit+0xe5/0xf0
WARNING: CPU: 0 PID: 12 at
drivers/gpu/drm/nouveau/nvkm/engine/gr/ctxgf100.c:1547
gf100_grctx_generate+0x7b2/0x850 [nouveau]
---[ end trace bf0976ed88b122a8 ]---
nouveau 0000:01:00.0: gr: wait for idle timeout (en: 1, ctxsw: 0, busy: 1)
nouveau 0000:01:00.0: gr: wait for idle timeout (en: 1, ctxsw: 0, busy: 1)
nouveau 0000:01:00.0: fifo: fault 01 [WRITE] at 0000000000008000 engine
00 [GR] client 15 [HUB/SCC_NB] reason c4 [] on channel -1 [0000000000
unknown]

>From which the GPU never manages to recover. Booting without nouveau
loading causes issues as well, since the GPU starts sending spurious
interrupts that cause other device's IRQs to get disabled by the kernel:

irq 16: nobody cared (try booting with the "irqpoll" option)
…
handlers:
[<000000007faa9e99>] i801_isr [i2c_i801]
Disabling IRQ #16
…
serio: RMI4 PS/2 pass-through port at rmi4-00.fn03
i801_smbus 0000:00:1f.4: Timeout waiting for interrupt!
i801_smbus 0000:00:1f.4: Transaction timeout
rmi4_f03 rmi4-00.fn03: rmi_f03_pt_write: Failed to write to F03 TX
register (-110).
i801_smbus 0000:00:1f.4: Timeout waiting for interrupt!
i801_smbus 0000:00:1f.4: Transaction timeout
rmi4_physical rmi4-00: rmi_driver_set_irq_bits: Failed to change enabled
interrupts!

Which in turn causes the touchpad and sometimes even other things to get
disabled.

Since the GPU staying on causes problems even without nouveau's
intervention, we can't fix this problem from nouveau itself. We have to
fix it as early as possible in the boot sequence in order to make sure
that the GPU is in a clean state before it has a chance to spam us with
interrupts and break things.

So to do this, we add a new pci quirk using
DECLARE_PCI_FIXUP_CLASS_FINAL that will be invoked before the PCI probe
at boot finishes. From there, we check to make sure that this is indeed
the specific P50 variant of this GPU. We also make sure that the GPU PCI
device is advertising NoReset- in order to prevent us from trying to
reset the GPU when the machine is in Dedicated graphics mode (where the
GPU being initialized by the BIOS is normal and expected). Finally, we
try mapping the MMIO space for the GPU which should only work if the GPU
is actually active in D0 mode. We can then read the magic 0x2240c
register on the GPU, which will have bit 1 set if the GPU's firmware has
already been posted during a previous boot. Once we've confirmed all of
this, we reset the PCI device and re-disable it - bringing the GPU back
into a healthy state.

Signed-off-by: Lyude Paul <lyude@...hat.com>
Cc: nouveau@...ts.freedesktop.org
Cc: dri-devel@...ts.freedesktop.org
Cc: Karol Herbst <kherbst@...hat.com>
Cc: Ben Skeggs <skeggsb@...il.com>
Cc: stable@...r.kernel.org
---
 drivers/pci/quirks.c | 65 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index b0a413f3f7ca..948492fda8bf 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -5117,3 +5117,68 @@ SWITCHTEC_QUIRK(0x8573);  /* PFXI 48XG3 */
 SWITCHTEC_QUIRK(0x8574);  /* PFXI 64XG3 */
 SWITCHTEC_QUIRK(0x8575);  /* PFXI 80XG3 */
 SWITCHTEC_QUIRK(0x8576);  /* PFXI 96XG3 */
+
+/*
+ * On certain Lenovo Thinkpad P50 SKUs, specifically those with a Nvidia
+ * Quadro M1000M, the BIOS will occasionally make the mistake of not resetting
+ * the nvidia GPU between reboots if the system is configured to use hybrid
+ * graphics mode. This results in the GPU being left in whatever state it was
+ * in during the previous boot which causes spurious interrupts from the GPU,
+ * which in turn cause us to disable the wrong IRQs and end up breaking the
+ * touchpad. Unsurprisingly, this also completely breaks nouveau.
+ *
+ * Luckily, it seems a simple reset of the PCI device for the nvidia GPU
+ * manages to bring the GPU back into a clean state and fix all of these
+ * issues. Additionally since the GPU will report NoReset+ when the machine is
+ * configured in Dedicated display mode, we don't need to worry about
+ * accidentally resetting the GPU when it's supposed to already be
+ * initialized.
+ */
+static void
+quirk_lenovo_thinkpad_p50_nvgpu_survives_reboot(struct pci_dev *pdev)
+{
+	void __iomem *map;
+	int ret;
+
+	if (pdev->subsystem_vendor != PCI_VENDOR_ID_LENOVO ||
+	    pdev->subsystem_device != 0x222e ||
+	    !pdev->reset_fn)
+		return;
+
+	/*
+	 * If we can't enable the device's mmio space, it's probably not even
+	 * initialized. This is fine, and means we can just skip the quirk
+	 * entirely.
+	 */
+	if (pci_enable_device_mem(pdev)) {
+		pci_dbg(pdev, "Can't enable device mem, no reset needed\n");
+		return;
+	}
+
+	/* Taken from drivers/gpu/drm/nouveau/engine/device/base.c */
+	map = ioremap(pci_resource_start(pdev, 0), 0x102000);
+	if (!map) {
+		pci_err(pdev, "Can't map MMIO space, this is probably very bad\n");
+		goto out_disable;
+	}
+
+	/*
+	 * Be extra careful, and make sure that the GPU firmware is posted
+	 * before trying a reset
+	 */
+	if (ioread32(map + 0x2240c) & 0x2) {
+		pci_info(pdev,
+			 FW_BUG "GPU left initialized by EFI, resetting\n");
+		ret = pci_reset_function(pdev);
+		if (ret < 0)
+			pci_err(pdev, "Failed to reset GPU: %d\n", ret);
+	}
+
+	iounmap(map);
+out_disable:
+	pci_disable_device(pdev);
+}
+
+DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_VENDOR_ID_NVIDIA, 0x13b1,
+			      PCI_CLASS_DISPLAY_VGA, 8,
+			      quirk_lenovo_thinkpad_p50_nvgpu_survives_reboot);
-- 
2.20.1

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