On 11.05.2023 22:02, Lukas Wunner wrote: > On Thu, May 11, 2023 at 09:49:52PM +0200, Heiner Kallweit wrote: >> On 11.05.2023 15:14, Ilpo Järvinen wrote: >>> Don't assume that only the driver would be accessing LNKCTL. ASPM >>> policy changes can trigger write to LNKCTL outside of driver's control. >>> >>> Use pcie_lnkctl_clear_and_set() which does proper locking to avoid >>> losing concurrent updates to the register value. >> >> Wouldn't it be more appropriate to add proper locking to the >> underlying pcie_capability_clear_and_set_word()? > > PCI config space accessors such as this one are also used in hot paths > (e.g. interrupt handlers). They should be kept lean (and lockless) I *think* in case the system uses threaded interrupts you may need locking also in interrupt handlers. > by default. We only need locking for specific PCIe Extended Capabilities > which are concurrently accessed by PCI core code and drivers. > > Thanks, > > Lukas
