Date: Fri, 7 Aug 2015 17:35:53 +0100
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Hurley <peter@hurleysoftware.com>,
        Peter Ujfalusi <peter.ujfalusi@ti.com>,
        Vinod Koul <vinod.koul@intel.com>,
        Dan Williams <dan.j.williams@intel.com>, dmaengine@vger.kernel.org,
        linux-kernel@vger.kernel.org, nsekhar@ti.com,
        linux-omap@vger.kernel.org, linux-serial@vger.kernel.org,
        john.ogness@linutronix.de, Greg KH <gregkh@linuxfoundation.org>
Subject: Re: [PATCH] dma: omap-dma: add support for pause of non-cyclic
 transfers
Message-ID: <20150807163553.GT7576@n2100.arm.linux.org.uk>
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 <55C48A1E.3070007@linutronix.de>
 <20150807132241.GN7576@n2100.arm.linux.org.uk>
 <55C4B5AE.10309@linutronix.de>
 <20150807135727.GP7576@n2100.arm.linux.org.uk>
 <55C4CA00.3060206@hurleysoftware.com>
 <20150807152939.GQ7576@n2100.arm.linux.org.uk>
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On Fri, Aug 07, 2015 at 06:20:44PM +0200, Sebastian Andrzej Siewior wrote:
> On 08/07/2015 06:07 PM, Peter Hurley wrote:
> >> If we look at what 8250-dma.c is doing:
> >>
> >>                 if (dma->rx_running) {
> >>                         dmaengine_pause(dma->rxchan);
> >>
> >> It's 8250-dma.c which is silently _ignoring_ the return code, failing
> >> to check that the operation it requested worked.  Maybe this should be
> >> WARN_ON(dmaengine_pause(dma->rxchan)) or at least it should print a
> >> message?
> > 
> > Thanks for the suggestion; I'll hold on to that and push it after we add
> > the 8250 omap dma pause in mainline.
> 
> I have a patch ready with WARN_ON_ONCE() for 8250-omap and 8250-dma.
> This warning would trigger on am335x/edma until v4.2-rc1 and omap-dma
> based version is open. I could post it if you want me to.
> Besides that those two, there are four other drivers ignoring the
> return code dmaengine_pause().

It'll probably be a good idea if those are fixed too, and also have a
__must_check annotation on the declaration of dmaengine_pause() to
prevent future mishaps like this.

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