On Tue, 4 Mar 2014, Sarah Sharp wrote:
> > David is right; this problem can't be fixed simply by reverting
> > patches. The real problem is that the block layer has handed the USB
> > stack an SG list that xhci-hcd cannot handle at all, in its current
> > form.
>
> We do not know if the driver n
On Tue, Mar 04, 2014 at 10:00:16AM -0500, Alan Stern wrote:
> On Tue, 4 Mar 2014, David Laight wrote:
>
> > > > Notice the request length: 1536. That's three 512-byte sectors. A
> > > > little unusual, since most I/O is done in units of pages, which are
> > > > 4096 bytes.
>
> > > Ok, we can't
From: Sarah Sharp
...
> The block layer may submit scatter-gather lists with entries that
> are multiples of 512-byte blocks. That's fine for USB 2.0 devices,
> where the bulk endpoint max packet size is 512 bytes. But USB 3.0
> devices have bulk endpoints with a 1024 byte max packet size.
>
> T
On Tue, 4 Mar 2014, Sarah Sharp wrote:
> Scatter-gather under xHCI seems to work fine on mass storage, but it
> fails with that particular ASIX device, because of how the xHCI driver
> sets up the buffers on the endpoint rings. We need to implement the TD
> fragment rules to avoid breaking this p
On Tue, Mar 04, 2014 at 10:45:34AM +0800, Ming Lei wrote:
> On Tue, Mar 4, 2014 at 5:47 AM, Sarah Sharp
> wrote:
> > Ok, we can't have SuperSpeed mass storage devices broken, so it looks
> > like we'll have to revert the last patch to add scatter-gather to the
> > ASIX driver to avoid that breaka
On Tue, 4 Mar 2014, David Laight wrote:
> > An alternative is to work around this particular problem by identifying
> > the code that submits the 3-sector SG element, and changing it to use
> > an even number of sectors. But obviously that doesn't solve the
> > underlying issue.
>
> Actually mos
On Tue, Mar 4, 2014 at 11:21 PM, David Laight wrote:
>
> Actually most of the block layer code could be taught to split requests
> into multiple URBs. Or even resubmit bounced requests split in two.
> Although splitting requests won't help the network code.
It might not help storage too since the
From: Alan Stern
> There are only two reasonable ways to fix this: Add appropriate TRB
> fragment handling into xhci-hcd, or use bounce buffers for non-aligned
> requests.
>
> In theory the block layer could be taught about the need for these
> bounce buffers, but that would be only a partial solu
On Tue, Mar 4, 2014 at 10:56 PM, David Laight wrote:
> From: Bjørn Mork
>> > If xHCI won't plan to support arbitrary-length scatter-gather any more,
>> > that
>> > is fine to revert the commit forever. Otherwise, it should be better to
>> > just
>> > clear no_sg_constraint in xhcd, shouldn't it
On Tue, 4 Mar 2014, David Laight wrote:
> > > Notice the request length: 1536. That's three 512-byte sectors. A
> > > little unusual, since most I/O is done in units of pages, which are
> > > 4096 bytes.
> > Ok, we can't have SuperSpeed mass storage devices broken, so it looks
> > like we'll ha
From: Bjørn Mork
> > If xHCI won't plan to support arbitrary-length scatter-gather any more, that
> > is fine to revert the commit forever. Otherwise, it should be better to
> > just
> > clear no_sg_constraint in xhcd, shouldn't it?
>
> No, that's what's currently causing bugs with the storage d
Ming Lei writes:
>>> The SG entries don't come from usb-storage; they come from the block
>>> layer. As far as I know, there is no way to tell the block layer that
>>> each element in an SG list (except the last) must be a multiple of
>>> some specific size.
>>>
>>> > revert commit 3804fad45411
From: Sarah Sharp
> Greg, Dave, Freddy, question about cross-subsystem reverts below:
>
> On Fri, Feb 28, 2014 at 04:15:12PM -0500, Alan Stern wrote:
> > On Fri, 28 Feb 2014, Sarah Sharp wrote:
> >
> > > When testing 3.14-rc1 with a USB 3.0 Lexar flash drive, the drive fails
> > > to be mounted.
On Tue, Mar 4, 2014 at 5:47 AM, Sarah Sharp
wrote:
> Greg, Dave, Freddy, question about cross-subsystem reverts below:
>
> On Fri, Feb 28, 2014 at 04:15:12PM -0500, Alan Stern wrote:
>> On Fri, 28 Feb 2014, Sarah Sharp wrote:
>>
>> > When testing 3.14-rc1 with a USB 3.0 Lexar flash drive, the driv
Greg, Dave, Freddy, question about cross-subsystem reverts below:
On Fri, Feb 28, 2014 at 04:15:12PM -0500, Alan Stern wrote:
> On Fri, 28 Feb 2014, Sarah Sharp wrote:
>
> > When testing 3.14-rc1 with a USB 3.0 Lexar flash drive, the drive fails
> > to be mounted. I added a bit of debugging to t
From: Alan Stern
> > When testing 3.14-rc1 with a USB 3.0 Lexar flash drive, the drive fails
> > to be mounted.
...
> > That revealed the SCSI request fails because the USB core is rejecting a
> > scatter-gather list with an entry that isn't aligned to the max packet size:
>
> > Feb 28 09:45:30 xa
On Fri, 28 Feb 2014, Sarah Sharp wrote:
> When testing 3.14-rc1 with a USB 3.0 Lexar flash drive, the drive fails
> to be mounted. I added a bit of debugging to the USB core:
>
> diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
> index 9ff665f1322f..eff59ac37865 100644
> --- a/driver
When testing 3.14-rc1 with a USB 3.0 Lexar flash drive, the drive fails
to be mounted. I added a bit of debugging to the USB core:
diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
index 9ff665f1322f..eff59ac37865 100644
--- a/drivers/usb/core/urb.c
+++ b/drivers/usb/core/urb.c
@@ -430
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