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author | Linus Torvalds <torvalds@linux-foundation.org> | 2019-07-15 20:44:49 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-07-15 20:44:49 -0700 |
commit | fb4da215ed92f564f7ca090bb81a199b0d6cab8a (patch) | |
tree | 38d4e18e1db026bec42c8b58ee40a245db313af3 /Documentation/power/s2ram.rst | |
parent | 2a3c389a0fde49b241430df806a34276568cfb29 (diff) | |
parent | 7b4b0f6b34d893be569da81ffad865a9d3a7d014 (diff) | |
download | linux-fb4da215ed92f564f7ca090bb81a199b0d6cab8a.tar.gz linux-fb4da215ed92f564f7ca090bb81a199b0d6cab8a.tar.bz2 linux-fb4da215ed92f564f7ca090bb81a199b0d6cab8a.zip |
Merge tag 'pci-v5.3-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci
Pull PCI updates from Bjorn Helgaas:
"Enumeration changes:
- Evaluate PCI Boot Configuration _DSM to learn if firmware wants us
to preserve its resource assignments (Benjamin Herrenschmidt)
- Simplify resource distribution (Nicholas Johnson)
- Decode 32 GT/s link speed (Gustavo Pimentel)
Virtualization:
- Fix incorrect caching of VF config space size (Alex Williamson)
- Fix VF driver probing sysfs knobs (Alex Williamson)
Peer-to-peer DMA:
- Fix dma_virt_ops check (Logan Gunthorpe)
Altera host bridge driver:
- Allow building as module (Ley Foon Tan)
Armada 8K host bridge driver:
- add PHYs support (Miquel Raynal)
DesignWare host bridge driver:
- Export APIs to support removable loadable module (Vidya Sagar)
- Enable Relaxed Ordering erratum workaround only on Tegra20 &
Tegra30 (Vidya Sagar)
Hyper-V host bridge driver:
- Fix use-after-free in eject (Dexuan Cui)
Mobiveil host bridge driver:
- Clean up and fix many issues, including non-identify mapped
windows, 64-bit windows, multi-MSI, class code, INTx clearing (Hou
Zhiqiang)
Qualcomm host bridge driver:
- Use clk bulk API for 2.4.0 controllers (Bjorn Andersson)
- Add QCS404 support (Bjorn Andersson)
- Assert PERST for at least 100ms (Niklas Cassel)
R-Car host bridge driver:
- Add r8a774a1 DT support (Biju Das)
Tegra host bridge driver:
- Add support for Gen2, opportunistic UpdateFC and ACK (PCIe protocol
details) AER, GPIO-based PERST# (Manikanta Maddireddy)
- Fix many issues, including power-on failure cases, interrupt
masking in suspend, UPHY settings, AFI dynamic clock gating,
pending DLL transactions (Manikanta Maddireddy)
Xilinx host bridge driver:
- Fix NWL Multi-MSI programming (Bharat Kumar Gogada)
Endpoint support:
- Fix 64bit BAR support (Alan Mikhak)
- Fix pcitest build issues (Alan Mikhak, Andy Shevchenko)
Bug fixes:
- Fix NVIDIA GPU multi-function power dependencies (Abhishek Sahu)
- Fix NVIDIA GPU HDA enablement issue (Lukas Wunner)
- Ignore lockdep for sysfs "remove" (Marek Vasut)
Misc:
- Convert docs to reST (Changbin Du, Mauro Carvalho Chehab)"
* tag 'pci-v5.3-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci: (107 commits)
PCI: Enable NVIDIA HDA controllers
tools: PCI: Fix installation when `make tools/pci_install`
PCI: dwc: pci-dra7xx: Fix compilation when !CONFIG_GPIOLIB
PCI: Fix typos and whitespace errors
PCI: mobiveil: Fix INTx interrupt clearing in mobiveil_pcie_isr()
PCI: mobiveil: Fix infinite-loop in the INTx handling function
PCI: mobiveil: Move PCIe PIO enablement out of inbound window routine
PCI: mobiveil: Add upper 32-bit PCI base address setup in inbound window
PCI: mobiveil: Add upper 32-bit CPU base address setup in outbound window
PCI: mobiveil: Mask out hardcoded bits in inbound/outbound windows setup
PCI: mobiveil: Clear the control fields before updating it
PCI: mobiveil: Add configured inbound windows counter
PCI: mobiveil: Fix the valid check for inbound and outbound windows
PCI: mobiveil: Clean-up program_{ib/ob}_windows()
PCI: mobiveil: Remove an unnecessary return value check
PCI: mobiveil: Fix error return values
PCI: mobiveil: Refactor the MEM/IO outbound window initialization
PCI: mobiveil: Make some register updates more readable
PCI: mobiveil: Reformat the code for readability
dt-bindings: PCI: mobiveil: Change gpio_slave and apb_csr to optional
...
Diffstat (limited to 'Documentation/power/s2ram.rst')
-rw-r--r-- | Documentation/power/s2ram.rst | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/Documentation/power/s2ram.rst b/Documentation/power/s2ram.rst new file mode 100644 index 000000000000..d739aa7c742c --- /dev/null +++ b/Documentation/power/s2ram.rst @@ -0,0 +1,87 @@ +======================== +How to get s2ram working +======================== + +2006 Linus Torvalds +2006 Pavel Machek + +1) Check suspend.sf.net, program s2ram there has long whitelist of + "known ok" machines, along with tricks to use on each one. + +2) If that does not help, try reading tricks.txt and + video.txt. Perhaps problem is as simple as broken module, and + simple module unload can fix it. + +3) You can use Linus' TRACE_RESUME infrastructure, described below. + +Using TRACE_RESUME +~~~~~~~~~~~~~~~~~~ + +I've been working at making the machines I have able to STR, and almost +always it's a driver that is buggy. Thank God for the suspend/resume +debugging - the thing that Chuck tried to disable. That's often the _only_ +way to debug these things, and it's actually pretty powerful (but +time-consuming - having to insert TRACE_RESUME() markers into the device +driver that doesn't resume and recompile and reboot). + +Anyway, the way to debug this for people who are interested (have a +machine that doesn't boot) is: + + - enable PM_DEBUG, and PM_TRACE + + - use a script like this:: + + #!/bin/sh + sync + echo 1 > /sys/power/pm_trace + echo mem > /sys/power/state + + to suspend + + - if it doesn't come back up (which is usually the problem), reboot by + holding the power button down, and look at the dmesg output for things + like:: + + Magic number: 4:156:725 + hash matches drivers/base/power/resume.c:28 + hash matches device 0000:01:00.0 + + which means that the last trace event was just before trying to resume + device 0000:01:00.0. Then figure out what driver is controlling that + device (lspci and /sys/devices/pci* is your friend), and see if you can + fix it, disable it, or trace into its resume function. + + If no device matches the hash (or any matches appear to be false positives), + the culprit may be a device from a loadable kernel module that is not loaded + until after the hash is checked. You can check the hash against the current + devices again after more modules are loaded using sysfs:: + + cat /sys/power/pm_trace_dev_match + +For example, the above happens to be the VGA device on my EVO, which I +used to run with "radeonfb" (it's an ATI Radeon mobility). It turns out +that "radeonfb" simply cannot resume that device - it tries to set the +PLL's, and it just _hangs_. Using the regular VGA console and letting X +resume it instead works fine. + +NOTE +==== +pm_trace uses the system's Real Time Clock (RTC) to save the magic number. +Reason for this is that the RTC is the only reliably available piece of +hardware during resume operations where a value can be set that will +survive a reboot. + +pm_trace is not compatible with asynchronous suspend, so it turns +asynchronous suspend off (which may work around timing or +ordering-sensitive bugs). + +Consequence is that after a resume (even if it is successful) your system +clock will have a value corresponding to the magic number instead of the +correct date/time! It is therefore advisable to use a program like ntp-date +or rdate to reset the correct date/time from an external time source when +using this trace option. + +As the clock keeps ticking it is also essential that the reboot is done +quickly after the resume failure. The trace option does not use the seconds +or the low order bits of the minutes of the RTC, but a too long delay will +corrupt the magic value. |