Re: usb: dwc2: regression on MyBook Live Duo / Canyonlands since 4.3.0-rc4

On 5/14/2016 6:11 AM, Christian Lamparter wrote:

On Thursday, May 12, 2016 11:40:28 AM John Youn wrote:

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On 5/12/2016 6:30 AM, Christian Lamparter wrote:

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On Thursday, May 12, 2016 01:55:44 PM Arnd Bergmann wrote:

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On Thursday 12 May 2016 11:58:18 Christian Lamparter wrote:

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Detecting the endianess of the
device is probably the best future-proof solution, but it's also
considerably more work to do in the driver, and comes with a
tiny runtime overhead.

The runtime overhead is probably non-measurable compared with the cost
of the actual MMIOs.

Right. The code size increase is probably measurable (but still small),
the runtime overhead is not.

Ok, so no rebuts or complains have been posted.

I've tested the patch you made in: https://lkml.org/lkml/2016/5/9/354
and it works: 

Tested-by: Christian Lamparter <chunkeey@googlemail.com>

So, how do we go from here? There is are two small issues with the
original patch (#ifdef DWC2_LOG_WRITES got converted to lower case:
#ifdef dwc2_log_writes) and I guess a proper subject would be nice.  

Arnd, can you please respin and post it (cc'd stable as well)?
So this is can be picked up? Or what's your plan?

(I just realized my reply was stuck in my outbox, so the patch
went out first)

If I recall correctly, the rough consensus was to go with your longer
patch in the future (fixed up for the comments that BenH and
I sent), and I'd suggest basing it on top of a fixed version of
my patch.

Well, but it comes with the "overhead"! So this was just as I said:
"Let's look at it and see if it's any good"... And I think it isn't
since the usb/host/ehci people also opted for #ifdef CONFIG_BIG_ENDIAN
archs etc...

I slightly prefer the more general patch for future kernel versions.
The overhead will probably be negligible, but we can perform some
testing to make sure.

Can you resubmit with all gathered feedback?

Yes, here are the changes.

I've tested it on my MyBook Live Duo. The usbotg comes right up:
[12610.540004] dwc2 4bff80000.usbotg: USB bus 1 deregistered
[12612.513934] dwc2 4bff80000.usbotg: Specified GNPTXFDEP=1024 > 256
[12612.518756] dwc2 4bff80000.usbotg: EPs: 3, shared fifos, 2042 entries in SPRAM
[12612.530112] dwc2 4bff80000.usbotg: DWC OTG Controller
[12612.533948] dwc2 4bff80000.usbotg: new USB bus registered, assigned bus number 1
[12612.540083] dwc2 4bff80000.usbotg: irq 33, io mem 0x00000000

John: Can you run some perf test with it?

I've based this on:

commit 6ea2fffc9057a67df1994d85a7c085d899eaa25a
Author: Arnd Bergmann [off-list ref]
Date:   Fri May 13 15:52:27 2016 +0200

    usb: dwc2: fix regression on big-endian PowerPC/ARM systems

so naturally, it needs to be applied first.
Most of the conversion work was done by the attached
coccinelle semantic patches. 

I had to edit the __bic32 and __orr32 helpers by hand.
As well as some debugfs code and stuff in gadget.c.

Thanks Christian.

I'll keep this in our internal tree and send it to Felipe later. This
causes a bunch of conflicts that I have to fix up and I should do a
bit of testing as well.

And since there is a patch that fixes the regression this is can wait.

Regards,
John