mainlining shenanigans
4e6a13356f
On driver probe and on resume from system sleep, pciehp checks the Presence Detect State bit in the Slot Status register to bring up an occupied slot or bring down an unoccupied slot. Both code paths are identical, so deduplicate them per Mika's request. On probe, an additional check is performed to disable power of an unoccupied slot. This can e.g. happen if power was enabled by BIOS. It cannot happen once pciehp has taken control, hence is not necessary on resume: The Slot Control register is set to the same value that it had on suspend by pci_restore_state(), so if the slot was occupied, power is enabled and if it wasn't, power is disabled. Should occupancy have changed during the system sleep transition, power is adjusted by bringing up or down the slot per the paragraph above. To allow for deduplication of the presence check, move the power check to pcie_init(). This seems safer anyway, because right now it is performed while interrupts are already enabled, and although I can't think of a scenario where pciehp_power_off_slot() and the IRQ thread collide, it does feel brittle. However this means that pcie_init() may now write to the Slot Control register before the IRQ is requested. If both the CCIE and HPIE bits happen to be set, pcie_wait_cmd() will wait for an interrupt (instead of polling the Command Completed bit) and eventually emit a timeout message. Additionally, if a level-triggered INTx interrupt is used, the user may see a spurious interrupt splat. Avoid by disabling interrupts before disabling power. (Normally the HPIE and CCIE bits should be clear on probe, but conceivably they may already have been set e.g. by BIOS.) Signed-off-by: Lukas Wunner <lukas@wunner.de> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com> |
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.