Re: [PATCH v3] PCI: Reprogram bridge prefetch registers on resume
From: Bjorn Helgaas <hidden>
Date: 2018-09-18 21:32:44
On Thu, Sep 13, 2018 at 11:37:45AM +0800, Daniel Drake wrote:
On 38+ Intel-based Asus products, the nvidia GPU becomes unusable
after S3 suspend/resume. The affected products include multiple
generations of nvidia GPUs and Intel SoCs. After resume, nouveau logs
many errors such as:
fifo: fault 00 [READ] at 0000005555555000 engine 00 [GR] client 04
[HUB/FE] reason 4a [] on channel -1 [007fa91000 unknown]
DRM: failed to idle channel 0 [DRM]
Similarly, the nvidia proprietary driver also fails after resume
(black screen, 100% CPU usage in Xorg process). We shipped a sample
to Nvidia for diagnosis, and their response indicated that it's a
problem with the parent PCI bridge (on the Intel SoC), not the GPU.
Runtime suspend/resume works fine, only S3 suspend is affected.
We found a workaround: on resume, rewrite the Intel PCI bridge
'Prefetchable Base Upper 32 Bits' register (PCI_PREF_BASE_UPPER32). In
the cases that I checked, this register has value 0 and we just have to
rewrite that value.
Linux already saves and restores PCI config space during suspend/resume,
but this register was being skipped because upon resume, it already
has value 0 (the correct, pre-suspend value).
Intel appear to have previously acknowledged this behaviour and the
requirement to rewrite this register.
https://bugzilla.kernel.org/show_bug.cgi?id=116851#c23
Based on that, rewrite the prefetch register values even when that
appears unnecessary.
We have confirmed this solution on all the affected models we have
in-hands (X542UQ, UX533FD, X530UN, V272UN).
Additionally, this solves an issue where r8169 MSI-X interrupts were
broken after S3 suspend/resume on Asus X441UAR. This issue was recently
worked around in commit 7bb05b85bc2d ("r8169: don't use MSI-X on
RTL8106e"). It also fixes the same issue on RTL6186evl/8111evl on an
Aimfor-tech laptop that we had not yet patched. I suspect it will also
fix the issue that was worked around in commit 7c53a722459c ("r8169:
don't use MSI-X on RTL8168g").
Thomas Martitz reports that this change also solves an issue where
the AMD Radeon Polaris 10 GPU on the HP Zbook 14u G5 is unresponsive
after S3 suspend/resume.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=201069
Signed-off-by: Daniel Drake <redacted>Applied with Rafael's and Peter's reviewed-by to pci/enumeration for v4.20. Thanks for the the huge investigative effort!
quoted hunk
--- drivers/pci/pci.c | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-)diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 29ff9619b5fa..5d58220b6997 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c@@ -1289,12 +1289,12 @@ int pci_save_state(struct pci_dev *dev) EXPORT_SYMBOL(pci_save_state); static void pci_restore_config_dword(struct pci_dev *pdev, int offset, - u32 saved_val, int retry) + u32 saved_val, int retry, bool force) { u32 val; pci_read_config_dword(pdev, offset, &val); - if (val == saved_val) + if (!force && val == saved_val) return; for (;;) {@@ -1313,25 +1313,34 @@ static void pci_restore_config_dword(struct pci_dev *pdev, int offset, } static void pci_restore_config_space_range(struct pci_dev *pdev, - int start, int end, int retry) + int start, int end, int retry, + bool force) { int index; for (index = end; index >= start; index--) pci_restore_config_dword(pdev, 4 * index, pdev->saved_config_space[index], - retry); + retry, force); } static void pci_restore_config_space(struct pci_dev *pdev) { if (pdev->hdr_type == PCI_HEADER_TYPE_NORMAL) { - pci_restore_config_space_range(pdev, 10, 15, 0); + pci_restore_config_space_range(pdev, 10, 15, 0, false); /* Restore BARs before the command register. */ - pci_restore_config_space_range(pdev, 4, 9, 10); - pci_restore_config_space_range(pdev, 0, 3, 0); + pci_restore_config_space_range(pdev, 4, 9, 10, false); + pci_restore_config_space_range(pdev, 0, 3, 0, false); + } else if (pdev->hdr_type == PCI_HEADER_TYPE_BRIDGE) { + pci_restore_config_space_range(pdev, 12, 15, 0, false); + /* Force rewriting of prefetch registers to avoid + * S3 resume issues on Intel PCI bridges that occur when + * these registers are not explicitly written. + */ + pci_restore_config_space_range(pdev, 9, 11, 0, true); + pci_restore_config_space_range(pdev, 0, 8, 0, false); } else { - pci_restore_config_space_range(pdev, 0, 15, 0); + pci_restore_config_space_range(pdev, 0, 15, 0, false); } }-- 2.17.1
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