linux-kernel - Re: [PATCH 4/4] usb: musb: tusb6010

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Message-ID: <20170508152949.GE3489@atomide.com>
Date:   Mon, 8 May 2017 08:29:49 -0700
From:   Tony Lindgren <tony@...mide.com>
To:     Peter Ujfalusi <peter.ujfalusi@...com>
Cc:     b-liu@...com, gregkh@...uxfoundation.org,
        linux-usb@...r.kernel.org, linux-omap@...r.kernel.org,
        balbi@...nel.org, linux-kernel@...r.kernel.org,
        Aaro Koskinen <aaro.koskinen@....fi>
Subject: Re: [PATCH 4/4] usb: musb: tusb6010_omap: Convert to DMAengine API

* Peter Ujfalusi <peter.ujfalusi@...com> [170508 08:15]:
> Tony,
> 
> On 2017-05-06 01:55, Tony Lindgren wrote:
> > OK I verified that with the current mainline kernel using dma
> > and g_ether and your patches 1 to 3 I can run the variable size
> > ping test loop for few minutes before it just stops working and
> > I can see the legacy DMA interrupt increase depending on the
> > size of the packet. Then I checked with v4.1 kernel, and that
> > too seems to have the same issue.
> > 
> > I've also verified running the same variable size ping test with
> > your patch 4/4 makes things stop within just a few seconds. The
> > script I'm using for ping is below.
> > 
> > Anyways, what we really should ensure here is that the external
> > dmarequest line is properly triggering things with dmaengine :)
> > That's why I'm a bit worried your patch 4/4.
> > 
> > Oh and I also verified the GPMC timings we're using are the same
> > as in production n810 kernel so that should not be the issue.
> > 
> > And using the async access on n800 will not work as it will
> > produce corrupt transfer size register the report I posted
> > earlier is from n800 allowing it to use async transfers. On
> > n810 async transfers may work as I recall it having a newer
> > tusb6010 version.
> 
> I think I have nailed the issue. I had a bug in the omap-dma implementation
> of the port_window (sigh) and couple of issues in the tusb6010/*_omap, not
> introduced by the series.
> The ASYNC access is pretty unstable on n810 as well, I got corruption in the
> XFR_SIZE.
> I have been using the g_ncm gadget with "musb->g.quirk_avoids_skb_reserve =
> 1;" to ensure that we are using SYNC access.
> 
> I'm running your variable ping script for 2 hours now, it wrapped >130 times
> already, I also run a standalone ping with 2048 size in parallel, the n810
> is booted to nfsroot:
> 
> # cat /proc/interrupts | grep dma
>  29:    9483598      INTC  13 Edge      omap-dma-engine
> #
> 
> I need to clean up the code as I had debugs (disabled now) and stuff and I
> want to try the tusb6010 changes w/o the DMAengine conversion.

Hey that's good news!

Tony