On Thu, Jul 26, 2012 at 2:33 AM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > On Wed, 25 Jul 2012, Paul Zimmerman wrote: > >> > From: Alan Stern [mailto:stern@xxxxxxxxxxxxxxxxxxx] >> > Sent: Wednesday, July 25, 2012 12:48 PM >> > To: Paul Zimmerman >> > Cc: Rajaram R; Michal Nazarewicz; linux-usb@xxxxxxxxxxxxxxx >> > Subject: RE: usb : mass storage : short_not_ok for non usb3 udc >> > >> > On Wed, 25 Jul 2012, Paul Zimmerman wrote: >> > >> > > > > > I don't understand this either. What's wrong with setting >> > > > > > short_not_ok while at SuperSpeed? It shouldn't force the use of a >> > > > bounce buffer. >> > > > > > >> > > > > >> > > > > I have just brought back some code removed by patch "usb: fix mass >> > > > > storage gadgets to work with Synopsys UDC". >> > > > >> > > > Maybe while bringing it back you can remove the checks for SuperSpeed. >> > > > Is there any reason to keep them? >> > > >> > > Hi Alan, >> > > >> > > The problem only arises because at super-speed the MaxPacket size is >> > > 1024, which is greater than the sector size of 512. So the whole point of >> > > the patch is to fix the SuperSpeed operation, while allowing high-speed >> > > devices to operate as they always did. >> > >> > Don't the mass-storage drivers already operate correctly at SuperSpeed? >> > If not, what goes wrong? >> > >> > Besides, how could the patch possibly affect SuperSpeed operation? >> > Everything it does is protected by >> > >> > if (!gadget_is_superspeed(gadget)) >> > >> > So I'm afraid I don't understand your point. >> >> Sorry for not being clear. The original patch: >> >> http://www.spinics.net/lists/linux-usb/msg52549.html >> >> was required to make mass-storage work with DWC3 at SuperSpeed. >> However, it apparently broke platforms like musb which depend on >> short-not-ok being set. The current patch fixes that, by setting >> short-not-ok if not running SuperSpeed. DWC3 will still work fine >> with this latest patch, since its problem was only with SuperSpeed. > > Okay, that's fine. But it doesn't answer my earlier question: Is there > really any need for the SuperSpeed checks in this patch? > > In other words, will DWC3 continue to work correctly if short_not_ok is > set? Yes, that was my question earlier to this patch. > > Alan Stern > -- 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
