hi Greg: 2017-03-23 15:15 GMT+08:00 Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>: > On Thu, Mar 23, 2017 at 03:09:05PM +0800, pierre Kuo wrote: >> for sitd_link and itd_link, put wmb after the last memory access to make >> sure ehci->period[frame] is visible before starting period schedule > > Is this fixing a known issue/bug that people are hitting? Or are you > just finding this by looking at the code? I just finding this by looking at the code. > >> >> Signed-off-by: pierre Kuo <vichy.kuo@xxxxxxxxx> >> --- >> drivers/usb/host/ehci-sched.c | 6 ++++-- >> 1 file changed, 4 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c >> index 980a6b3..9bb708a 100644 >> --- a/drivers/usb/host/ehci-sched.c >> +++ b/drivers/usb/host/ehci-sched.c >> @@ -1754,8 +1754,9 @@ static void reserve_release_iso_bandwidth(struct ehci_hcd *ehci, >> itd->hw_next = *hw_p; >> prev->itd = itd; >> itd->frame = frame; >> - wmb(); >> *hw_p = cpu_to_hc32(ehci, itd->itd_dma | Q_TYPE_ITD); >> + /* make sure ehci->period[frame] is visible */ > > why an extra space in the comment? I use cvim template, and it will automatically put space at end of /* and before */ since ./scripts/checkpatch.pl didn't complain, so I sent it out. should I remove the space and resent again? > > And is the comment correct here? The comment is added due to ./scripts/checkpatch.pl grumble me there should be comment before wmb(); > >> + wmb(); >> } >> >> /* fit urb's itds into the selected schedule slot; activate as needed */ >> @@ -2157,8 +2158,9 @@ static int itd_submit(struct ehci_hcd *ehci, struct urb *urb, >> sitd->hw_next = ehci->periodic[frame]; >> ehci->pshadow[frame].sitd = sitd; >> sitd->frame = frame; >> - wmb(); >> ehci->periodic[frame] = cpu_to_hc32(ehci, sitd->sitd_dma | Q_TYPE_SITD); >> + /* make sure ehci->period[frame] is visible */ > > Same extra space question. > > thanks, > > greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
