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

[Subbaraya Sundeep Bhatta]

Hi,

> -----Original Message-----
> From: Peter Chen [mailto:peter.chen@xxxxxxxxxxxxx]
> Sent: Monday, August 31, 2015 7:59 AM
> To: Punnaiah Choudary Kalluri
> Cc: Nathan Sullivan; sundeep subbaraya; Subbaraya Sundeep Bhatta;
> robh+dt@xxxxxxxxxx; pawel.moll@xxxxxxx; Mark Rutland;
> ijc+devicetree@xxxxxxxxxxxxxx; Kumar Gala; Greg Kroah-Hartman;
> devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-
> usb@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH 1/2] usb: chipidea: add xilinx zynq platform data
> 
> On Mon, Aug 31, 2015 at 09:01:51AM +0530, punnaiah choudary kalluri
> wrote:
> > 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.
> >
> >
> 
> ok, so your platform can't use stream mode disabled.

This is patch can be applied then. Thank you all.

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