Hi, On Wed, Mar 18, 2015 at 05:17:04PM +0100, Alexander Sverdlin wrote: > On 18/03/15 17:11, ext David Daney wrote: > >> udelay() in PCI/PCIe read/write callbacks cause 30ms IRQ latency on Octeon > >> platforms because these operations are called from PCI_OP_READ() and > >> PCI_OP_WRITE() under raw_spin_lock_irqsave(). > >> > >> Signed-off-by: Alexander Sverdlin <alexander.sverdlin@xxxxxxxxx> > > > > Can you say how it was tested. In principle I have no objections, but it > > would be nice to know how it was validated. > > What do you want to know, how we've debugged IRQ latency and found the > root cause or how we figured out that delay is not necessary? You could at least say on which OCTEON platforms (e.g. OCTEON II or older) you tested the patch on, and tell about tested PCI bus topology and devices. > I'm pretty sure that there is HW which requires it. Maybe it's > even Octeon itself... But putting udelay() in this callbacks is > wrong wrong wrong. Still, you should not break HW that works with current kernel. A.
