On 9/10/2012 6:49 PM, Felipe Balbi wrote:
On Mon, Sep 10, 2012 at 06:45:06PM +0530, Pratyush Anand wrote:
Hi Felip,
Thanks for the clarifications.
On 9/10/2012 6:29 PM, Felipe Balbi wrote:
If my understanding is correct, then I might need to modify dwc3
driver a bit. only first TRB of the service interval should have
TRBCTL as ISOC_FIRST rest should have TRBCTL as ISOC.
Why ? IIRC, ISOC_FIRST was a hint to the internal packet scheduler to
give higher priority to the isochronous packet, right ? Does it make any
difference for your use case ?
Databook says:
"The first TRB in a Buffer Descriptor must have the TRBCTL field set
to the “Isochronous-First” type while all others have this field set
to “Isochronous”."
aaa true :-) I had forgotten about that extra bit of information when
using chained TRBs :-s My bad. Please send a patch.
So I thought to modify the code. As of now, ISOC IN does not work
fully with either All Isochronous-First or Isochronous First +
Isochronous implementation (in case of more than one TRB for one
service interval).
May be I am doing some mistake in my code. :(
I am debugging. Will get back with my observations.
I think you're perfectly right at the need for ISOCHRONOUS_FIRST flag.
My bad.
Hummm.. It works with "Isochronous First + Isochronous" implementation.
But, code needs many modification..
We have one trb and one trb_dma per "struct dwc3_request". We take lot
of decisions on the basis of req->trb value. These all will change in
case of SG. We will not have only one TRB per "struct usb_request".
I am going to keep array for trb and trb_dma and then to manage all
these with backward compatibility (non SG case). What do you say?
struct dwc3_trb *trb[DWC3_TRB_NUM];
dma_addr_t trb_dma[DWC3_TRB_NUM];
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