On Fri, Aug 22, 2025 at 11:59:01PM +0800, Hans Zhang wrote:
> This series replaces short msleep() calls (less than 20ms) with more
> precise delay functions (fsleep() and usleep_range()) throughout the
> PCI subsystem.
>
> The msleep() function with small values can sleep longer than intended
> due to timer granularity, which can cause unnecessary delays in PCI
> operations such as link status checking, reset handling, and hotplug
> operations.
>
> These changes:
> - Use fsleep() for delays that require precise timing (1-2ms).
> - Use usleep_range() for delays that can benefit from a small range.
> - Add #defines for all delay values with references to PCIe specifications.
> - Update comments to reference the latest PCIe r7.0 specification.
>
> This improves the responsiveness of PCI operations while maintaining
> compliance with PCIe specifications.
I would split this a little differently:
- Add #defines for values from PCIe base spec. Make the #define
value match the spec value. If there's adjustment, e.g.,
doubling, do it at the sleep site. Adjustment like this seems a
little paranoid since the spec should already have some margin
built into it.
- Change to fsleep() (or usleep_range()) in separate patch. There
might be discussion about these changes, but the #defines are
desirable regardless.
I'm personally dubious about the places you used usleep_range().
These are low-frequency paths (rcar PHY ready, brcmstb link up,
hotplug command completion, DPC recover) that don't seem critical. I
think they're all using made-up delays that don't come from any spec
or hardware requirement anyway. I think it's hard to make an argument
for precision here.
Bjorn
