Re: [PATCH 1/2] usb: chipidea: add xilinx zynq platform data

[punnaiah choudary kalluri]

On Mon, Aug 31, 2015 at 6:10 AM, Peter Chen <peter.chen@xxxxxxxxxxxxx> wrote:
> On Fri, Aug 28, 2015 at 09:42:56AM -0500, Nathan Sullivan wrote:
>> On Fri, Aug 28, 2015 at 09:30:12AM +0800, Peter Chen wrote:
>> > On Thu, Aug 27, 2015 at 09:33:07AM -0500, Nathan Sullivan wrote:
>> > > On Thu, Aug 27, 2015 at 01:11:30PM +0530, punnaiah choudary kalluri wrote:
>> > > > Hi,
>> > > >
>> > > > On Thu, Aug 27, 2015 at 10:03 AM, Peter Chen <peter.chen@xxxxxxxxxxxxx> wrote:
>> > > > > On Thu, Aug 27, 2015 at 10:59:22AM +0530, sundeep subbaraya wrote:
>> > > > >> Hi,
>> > > > >>
>> > > > >>
>> > > > >> On Wed, Aug 26, 2015 at 8:57 PM, Nathan Sullivan <nathan.sullivan@xxxxxx> wrote:
>> > > > >> > The Xilinx Zynq udc does not need the CI_HDRC_DISABLE_STREAMING flag,
>> > > > >> > unlike the default platform data.  Add platform data specific to the
>> > > > >> > Zynq udc.
>> > > > >> >
>> > > > >> > Based on a patch by the same name from the Xilinx vendor tree.
>> > > > >>
>> > > > >> I am that Xilinx guy who sent this patch :). It is in Xilinx tree as
>> > > > >> temporary fix and
>> > > > >> I did not debug further why UDC works only when streaming is enabled.
>> > > > >> Probably this is right time to post my question here.
>> > > > >> I was expecting like:
>> > > > >> Streaming disabled - both low bandwidth and high bandwidth systems
>> > > > >> should work fine
>> > > > >> Streaming enabled - only for high bandwidth systems
>> > > > >> but this is not the case, Zynq UDC works only when Streaming is enabled.
>> > > > >> Please correct me if I am wrong.
>> > > > >
>> > > > > You are right, stream mode disabled should work at anytime.
>> > > > > It is so strange why zynq UDC only works when stream mode is enabled.
>> > > >
>> > > > I am referring the section 8.5.2 in Synopsys usb 2.0 HS controllervDoc 2.20a,
>> > > >  this is what it says about SDIS (streaming mode disable option)
>> > > >
>> > > > Before activating this mode, the user must check if the TX latency
>> > > > buffers per endpoint are able to
>> > > > accommodate at least one entire maximum size packet. The RX buffer
>> > > > size must, at least, double the TX
>> > > > buffer size per endpoint. To optimize the stream disable performance,
>> > > > system bus burst must be set as high
>> > > > as possible.
>> > > > When the stream disable mode is used, the burst size (VUSB_HS_RX_BURST
>> > > > and VUSB_HS_TX_BURST)
>> > > > must be a integer sub-multiple of the latency buffer size
>> > > > (VUSB_HS_RX_DEPTH for RX buffer and
>> > > > VUSB_HS_TX_CHAN for the TX buffer). If this is not respected the
>> > > > controller will not work properly in stream
>> > > > disable mode.
>> > > > The stream disable mode should just be used in situations where the
>> > > > available system bandwidth is low or the
>> > > > system bus access latency is high, in order to avoid underruns and
>> > > > overruns in the latency buffers. This works
>> > > > for all types of endpoints, except for ISO endpoints.
>> > > > Such a system can't ensure the real time support that the ISO
>> > > > endpoints require, so the ISO endpoints are not
>> > > > supported when the SDIS bit is set.
>> > > >
>> > > > Definitely we need to root cause why disable streaming mode is not
>> > > > working for zynq but from controller spec
>> > > > point of view it is possible that controller not work properly in
>> > > > stream disable mode.
>> > > >
>> > > > Regards,
>> > > > Punnaiah
>> > > >
>> > >
>> > > Maybe the burst size isn't set correctly by default?  It does say the controller
>> > > won't work correctly with stream disable set and an invalid burst size.  Looks
>> > > like TX and RX burst both default to 16, per the Zynq manual.
>> > >
>> > > With the stream disable bit set, the behvior we see on our hardware is
>> > > that priming just stops, with an outstanding transfer in memory marked
>> > > active in the status field by the controller.  This happens at random, even
>> > > when doing single transfers at a time like with g_ether set to have a queue
>> > > size of 1.  With SDIS clear everything works great.  Given that the Zynq is not
>> > > bandwidth constrained, it seems like SDIS clear should be the default.
>> > >
>> >
>> > I suspect the possible reason is the tx buffer for each endpoint is
>> > small (<=512 bytes), so it can't copy one packet (assume max packet size
>> > for bulk) to tx buffer, then the prime can't be finished.
>> >
>> > Would you help to dump the registers HWTXBUF ($BASE + 0x10) and DCCPARAMS
>> > ($BASE + 124)?
>> >
>> > tx buffer size = ((2 ^ HWTXBUF.VUSB_HS_TX_ADD) / DCCPARAMS.DEN) *
>> > (DWORD_PER_BYTES)
>> >
>> > DWORD_PER_BYTES is 4
>> >
>> > --
>> >
>> > Best Regards,
>> > Peter Chen
>>
>> HWTXBUF is 0x80060A10, DCCPARAMS is 0xE0003124.
>
> Are you sure you read correct address? Your DCCPARAMS means
> it is host capable, but not device capable.

HWTXBUF is 0x8060A10
DCCPARAMS is 0x0000018C

VUSB_HS_TX_ADD - 0xA
DEN - 0xC

>From the above formula tx buffer size is 341.33 bytes.


Regards,
Punnaiah

>
> --
>
> Best Regards,
> Peter Chen
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