linux-kernel - Re: [BUG] Serial/dma stall/failure after "dmaengine: fsl-edma: extract common fsl-edma code (no changes in behavior intended)"

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Message-ID: <20180706085533.GA5373@jerusalem>
Date:   Fri, 6 Jul 2018 10:55:34 +0200
From:   Angelo Dureghello <angelo@...am.it>
To:     Krzysztof Kozlowski <krzk@...nel.org>
Cc:     Vinod <vkoul@...nel.org>, Stefan Agner <stefan@...er.ch>,
        dmaengine@...r.kernel.org, Dan Williams <dan.j.williams@...el.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [BUG] Serial/dma stall/failure after "dmaengine: fsl-edma:
 extract common fsl-edma code (no changes in behavior intended)"

Hi,

On Fri, Jul 06, 2018 at 08:16:29AM +0200, Krzysztof Kozlowski wrote:
> On 6 July 2018 at 08:05, Vinod <vkoul@...nel.org> wrote:
> > On 05-07-18, 18:23, Angelo Dureghello wrote:
> >> Hi Stafan,
> >>
> >> On Thu, Jul 05, 2018 at 05:55:31PM +0200, Stefan Agner wrote:
> >> > Hi Vinod, Hi Angelo,
> >> >
> >> > On 05.07.2018 14:45, Angelo Dureghello wrote:
> >> > > Hi Vinod,
> >> > >
> >> > > On Thu, Jul 05, 2018 at 10:12:53AM +0200, Angelo Dureghello wrote:
> >> > >> Hi Vinod,
> >> > >>
> >> > >> On Thu, Jul 05, 2018 at 01:05:52PM +0530, Vinod wrote:
> >> > >> > On 04-07-18, 10:54, Krzysztof Kozlowski wrote:
> >> > >> > > Hi,
> >> > >> > >
> >> > >> > > The commit 6ad069123f03bebe4315dea13d44845854ca6043 ("dmaengine:
> >> > >> > > fsl-edma: extract common fsl-edma code (no changes in behavior
> >> > >> > > intended)"), even though marked as no changes in behavior intended...
> >> > >> > > make serial console with DMA broken after boot. The console just hangs
> >> > >> > > - is not responsive even to SysRq. Usually after finishing boot -
> >> > >> > > before or after login prompt. Sometimes login is allowed and then it
> >> > >> > > hangs during printing dmesg.
> >> > >> > >
> >> > >> > > Board: Toradex Colibri VF50 (NXP VF500, Cortex A5, serial configured
> >> > >> > > with DMA) on Iris Carrier.
> >> > >> >
> >> > >> > Angelo ?
> >> > >> >
> >> > >> sorry for this. As said i couldn't test it in any of those arm boards
> >> > >> but i take a look.
> >> > >>
> >> > >> The only code part that changes is the initial setting up of the registers.
> >> > >> I am checking that.
> >> > >>
> >> > >> Regards,
> >> > >> Angelo
> >> > >>
> >> > >
> >> > > I cannot find anything obviously wrong.
> >> > > And i cannot test on Vybrid.
> >> > > I will try to get a Vybrid V50 board to test this issue. It would
> >> > > require some days and also i wil be 3 weeks off on July.
> >> > >
> >> > > So please revert my patch.
> >> >
> >> > I did not found the issue quickly. But I must say that I gave up pretty
> >> > quickly. There are too many changes in a single patch which makes it
> >> > hard to figure out what could be wrong. I'd rather prefer if we could
> >> > drop that patch again and go through another review phase.
> >> >
> >> > Angelo, as far as I can see the patch has not been sent to LKML or the
> >> > ARM mailing list. Especially since you do not have such a device it
> >> > would have been nice to also send it to the ARM mailing list...
> >> >
> >> > Can you resend your last revision with CC to me/ARM mailing list?
> >> >
> >>
> >> Thanks for looking into it.
> >>
> >> I have spent a lot of time on this patch and really would have
> >> dma for Coldfire available. So, have ordered a Colibri / v50 board.
> >>
> >> Should receive it in few days and should be able to debug this issue,
> >> but as said, i will be off for some weeks so looks like it is probably
> >> better to revert the patch.
> >>
> >> My initial submit was a separate driver, to avoid such issues where
> >> i cannot test, but it resulted in too much duplicated code.
> >>
> >> Sure, i can send the full patch to you/arm with all the fixes included
> >> until now.
> >
> > Okay dropped now from -next. I still keeping topic/fsl around and
> > collect other fixes for you guys to check.
> >
> > One way would be to split to common patch into multiple patch and check
> > regression. That should help quickly identify the issue.
> 
> Even with show -C20% -M20% I gave up when trying to spot possible
> differences in the commit. I understand that logically it is one
> change and it makes sense... but it touches, moves and adds too much
> making review extremely difficult. I think the splitting into smaller
> chunks would be beneficial anyway.
> 
> Today's next boots fine.
> 

Good, will resend the patch once splitted in more commits, and 
tested on V50 Vybrid.

Regards,
Angelo

> Best regards,
> Krzysztof
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