On Thu, Aug 11, 2022 at 06:40:01PM +0000, Will McVicker wrote: > From: Sajid Dalvi <sdalvi@xxxxxxxxxx> > > Since the PCI spec requires a 10ms D3Hot delay (defined by > PCI_PM_D3HOT_WAIT) and a few of the PCI quirks update the D3Hot delay up > to 20ms, let's switch from msleep to usleep_range to improve the delay > accuracy. > > This patch came from Sajid Dalvi <sdalvi@xxxxxxxxxx> in the Pixel 6 > kernel tree [1]. Testing on a Pixel 6, found that the 10ms delay for > the Exynos PCIe device was on average delaying for 19ms when the spec > requires 10ms. Switching from msleep to uslseep_delay therefore > decreases the resume time on a Pixel 6 on average by 9ms. > > [1] https://android.googlesource.com/kernel/gs/+/18a8cad68d8e6d50f339a716a18295e6d987cee3 > > Signed-off-by: Sajid Dalvi <sdalvi@xxxxxxxxxx> > Signed-off-by: Will McVicker <willmcvicker@xxxxxxxxxx> > --- > drivers/pci/pci.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index 95bc329e74c0..5ae5b3c4dc9b 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -72,7 +72,8 @@ static void pci_dev_d3_sleep(struct pci_dev *dev) > delay = pci_pm_d3hot_delay; > > if (delay) > - msleep(delay); > + usleep_range(delay * USEC_PER_MSEC, > + (delay + 2) * USEC_PER_MSEC); You could also use fsleep(), which ends up calling usleep_range() for (usecs > 10 && usecs <= 20000).
