| Message ID | 20190618161858.77834-1-mika.westerberg@linux.intel.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | PCI / ACPI: Handle sibling devices sharing power resources | expand |
On Tue, Jun 18, 2019 at 6:19 PM Mika Westerberg <mika.westerberg@linux.intel.com> wrote: > > Hi all, > > Based on a discussion regarding patch series I sent previously [1] to deal > with sibling devices sharing ACPI power resources, I prepared a new > reworked version according to the comments I got. > > To summarize, in Intel Ice Lake the Thunderbolt controller, PCIe root ports > and xHCI all share power resources. When they are all in D3hot power > resources (returned by _PR3) can be turned off powering off the whole > block. However, there are two issues around this. > > Firstly the PCI core sets the device power state by asking what the real > ACPI power state is. This results that all but last device sharing the > power resources are in D3hot when the power resources are turned off. This > causes issues if user runs for example 'lspci' because the device is really > in D3cold so what user gets back is all ones (0xffffffff). > > Secondly if any of the device is runtime resumed the power resources are > turned on bringing all other devices sharing the resources to > D0uninitialized losing their wakeup configuration. > > This series aims to fix the two issues by: > > 1. Using the ACPI cached power state when PCI devices are transitioned > into low power states instead of reading back the "real" power state. > > 2. Introducing concept of "_PR0 dependent devices" that get runtime > resumed whenever their power resource (which they might share with > other sibling devices) gets turned on. > > The series is based on the idea of Rafael J. Wysocki <rafael@kernel.org>. > > [1] https://www.spinics.net/lists/linux-pci/msg83583.html > > Mika Westerberg (3): > PCI / ACPI: Use cached ACPI device state to get PCI device power state > ACPI / PM: Introduce concept of a _PR0 dependent device > PCI / ACPI: Add _PR0 dependent devices LGMT overall, patch [2/3] can be simplified slightly IMO (already sent comments for that one). As far as I'm concerned, the other patches need not be updated.
Hi all, Based on a discussion regarding patch series I sent previously [1] to deal with sibling devices sharing ACPI power resources, I prepared a new reworked version according to the comments I got. To summarize, in Intel Ice Lake the Thunderbolt controller, PCIe root ports and xHCI all share power resources. When they are all in D3hot power resources (returned by _PR3) can be turned off powering off the whole block. However, there are two issues around this. Firstly the PCI core sets the device power state by asking what the real ACPI power state is. This results that all but last device sharing the power resources are in D3hot when the power resources are turned off. This causes issues if user runs for example 'lspci' because the device is really in D3cold so what user gets back is all ones (0xffffffff). Secondly if any of the device is runtime resumed the power resources are turned on bringing all other devices sharing the resources to D0uninitialized losing their wakeup configuration. This series aims to fix the two issues by: 1. Using the ACPI cached power state when PCI devices are transitioned into low power states instead of reading back the "real" power state. 2. Introducing concept of "_PR0 dependent devices" that get runtime resumed whenever their power resource (which they might share with other sibling devices) gets turned on. The series is based on the idea of Rafael J. Wysocki <rafael@kernel.org>. [1] https://www.spinics.net/lists/linux-pci/msg83583.html Mika Westerberg (3): PCI / ACPI: Use cached ACPI device state to get PCI device power state ACPI / PM: Introduce concept of a _PR0 dependent device PCI / ACPI: Add _PR0 dependent devices drivers/acpi/power.c | 139 ++++++++++++++++++++++++++++++++++++++++ drivers/pci/pci-acpi.c | 5 +- include/acpi/acpi_bus.h | 4 ++ 3 files changed, 147 insertions(+), 1 deletion(-)