2017-03-23 15:55 GMT+08:00 Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>: > On Thu, Mar 23, 2017 at 03:39:20PM +0800, pierre kuo wrote: >> 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 */ > > That's fine, but why did you add another one manually? oh, I found what you mean, there are 2 spaces after "/*" I will fix it. > >> since ./scripts/checkpatch.pl didn't complain, so I sent it out. >> should I remove the space and resent again? > > Of course. got it > >> > And is the comment correct here? >> The comment is added due to ./scripts/checkpatch.pl grumble me there >> should be comment before wmb(); > > Is the text of the comment correct? It doesn't seem so to me... I got ur point, the comment seems a little bit short for describing what we want. I will try to make it more clear and also succinct. thanks for your suggestion. -- 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
