From: Johan Hovold <johan@kernel.org>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Johan Hovold <johan@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Felipe Balbi <balbi@ti.com>,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
Stephen Warren <swarren@wwwdotorg.org>,
Thierry Reding <thierry.reding@gmail.com>,
Alexandre Courbot <gnurou@gmail.com>,
linux-tegra@vger.kernel.org, stable <stable@vger.kernel.org>
Subject: Re: [PATCH 2/2] USB: ehci-tegra: fix inefficient copy of unaligned buffers
Date: Tue, 7 Apr 2015 21:59:32 +0200 [thread overview]
Message-ID: <20150407195932.GB12027@localhost> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1504071127210.1430-100000@iolanthe.rowland.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
prev parent reply other threads:[~2015-04-07 19:59 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1428400012-7563-1-git-send-email-johan@kernel.org>
2015-04-07 9:46 ` [PATCH 1/2] USB: musb: fix inefficient copy of unaligned buffers Johan Hovold
2015-04-07 9:46 ` [PATCH 2/2] USB: ehci-tegra: " Johan Hovold
2015-04-07 15:30 ` Alan Stern
2015-04-07 19:59 ` Johan Hovold [this message]
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