From mboxrd@z Thu Jan 1 00:00:00 1970 From: Johan Hovold Subject: Re: [PATCH 2/2] USB: ehci-tegra: fix inefficient copy of unaligned buffers Date: Tue, 7 Apr 2015 21:59:32 +0200 Message-ID: <20150407195932.GB12027@localhost> References: <1428400012-7563-3-git-send-email-johan@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Alan Stern Cc: Johan Hovold , Greg Kroah-Hartman , Felipe Balbi , linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Stephen Warren , Thierry Reding , Alexandre Courbot , linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, stable List-Id: linux-tegra@vger.kernel.org On Tue, Apr 07, 2015 at 11:30:15AM -0400, Alan Stern wrote: > On Tue, 7 Apr 2015, Johan Hovold wrote: > > > Make sure only to copy any actual data rather than the whole buffer, > > when releasing the temporary buffer used for unaligned transfer buffers. > > > > Note that the corresponding fix of musb also fixes a lockup on > > disconnect, where repeated failed transfers would starve the hub > > workqueue from processing the disconnect, which would have prevented the > > urbs from being resubmitted. In this case there is no data to forward, > > but the full buffer length was being copied nonetheless. > > This is wrong for isochronous transfers, because the transfer data > generally isn't contiguous in memory. > > It would be okay to do this for other transfer types, though. Thanks for pointing that out. I'll re-spin the series tomorrow. Johan