On Thu, Mar 21, 2013 at 09:07:42AM +0800, Peter Chen wrote:
> On Wed, Mar 20, 2013 at 10:30:47AM +0100, Michael Grzeschik wrote:
> > On Wed, Mar 20, 2013 at 09:17:06AM +0800, Peter Chen wrote:
> > > On Tue, Mar 19, 2013 at 01:02:59PM +0100, Michael Grzeschik wrote:
> > > > On Tue, Mar 19, 2013 at 09:34:54AM +0800, Peter Chen wrote:
> > > > > On Mon, Mar 18, 2013 at 03:28:26PM +0100, Michael Grzeschik wrote:
> > > > > > On Fri, Mar 08, 2013 at 05:54:37PM +0200, Alexander Shishkin wrote:
> > > > > > > Michael Grzeschik <[email protected]> writes:
> > > > > > >
> > > > > > > > A static count of transfer descriptors was used everywhere in
> > > > > > > > the driver
> > > > > > > > with the fixed number 4. This patch adds a define, named
> > > > > > > > TD_COUNT, and
> > > > > > > > replaces all users of this value. This way its possible to have
> > > > > > > > only one
> > > > > > > > parameter to change and limit the amount of tds per transfer.
> > > > > > >
> > > > > > > I think Svetoslav made exactly the same patch in his patchset,
> > > > > > > but I
> > > > > > > think this patchset will go first.
> > > > > >
> > > > > > I did not find any patch comparable by Svetoslav. But, that patch
> > > > > > is superseeded by that hunk in my current branch anyway, as every
> > > > > > TD can
> > > > > > maintain five DMA buffers:
> > > > > >
> > > > > > diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c
> > > > > > index 09bc6ea..c961e3b 100644
> > > > > > --- a/drivers/usb/chipidea/udc.c
> > > > > > +++ b/drivers/usb/chipidea/udc.c
> > > > > > @@ -688,8 +688,8 @@ static int _ep_queue(struct usb_ep *ep, struct
> > > > > > usb_request *req)
> > > > > > goto done;
> > > > > > }
> > > > > >
> > > > > > - if (req->length > 4 *
> > > > > > CI13XXX_PAGE_SIZE) {
> > > > > > - req->length = 4 *
> > > > > > CI13XXX_PAGE_SIZE;
> > > > > > + if (req->length > 5 *
> > > > > > CI13XXX_PAGE_SIZE) {
> > > > > > + req->length = 5 *
> > > > > > CI13XXX_PAGE_SIZE;
> > > > > > retval = -EMSGSIZE;
> > > > > >
> > > > > > dev_warn(mEp->ci->dev, "request length truncated\n");
> > > > > > }
> > > > >
> > > > > No, 4 is ok. There are 5 buffer Pointers are dTD, but the Buffer
> > > > > Point 0
> > > > > may not 4K aligned. Eg, if the reg->length is 18KB, and the buf DMA
> > > > > address
> > > > > is 1K aligned, it needs two dTDs.
> > > > > The first dTD only uses: 1KB, 4KB, 4KB, 4KB, 4KB as 5 buffers space.
> > > >
> > > > When the first pointer is not aligned, then all other buffer pointers
> > > > will also not be.
> > >
> > > Please have a look of dTD descriptor at spec, the pointer 0 can be
> > > not 4k-aligned (the size is address - address & 4KB), but other
> > > buffer pointers are 4k-aligned required.
> >
> > Can you point me to an document with exact page?
> >
>
> Just search "Endpoint Transfer Descriptor" at USB chapter at any Freescale
> SoC reference manual.
I think i get it now. From reading the dTD Buffer Pointer List Descriptions
in the Device [¹] and Host sections. The adressing pattern can be like that:
1KB, 4K, 4KB, 4KB, ...
With that constraint, the code is currently correct. But i prefer to
have this handled as an special case. I will cook another patch that
will check for (mReq->req.dma % PAGE_SIZE) and repost my series
afterwards.
Thanks,
Michael
[¹] Table 77-63. dTD Buffer Page Pointer List
------------------------------------------------------------------------------------------
Bit | Description
------------------------------------------------------------------------------------------
31-12 | Buffer Pointer. Selects the page offset in memory for the
packet buffer.
| Non virtual memory systems will typically set the buffer
pointers to a
| series of incrementing integers.
------------------------------------------------------------------------------------------
0,11-0 | Current Offset. Offset into the 4kb buffer where the packet is
to begin.
------------------------------------------------------------------------------------------
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