linux-kernel - Re: [PATCH] dma: omap-dma: add support for pause of non-cyclic transfers

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Message-ID: <20150807132241.GN7576@n2100.arm.linux.org.uk>
Date:	Fri, 7 Aug 2015 14:22:41 +0100
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:	Peter Ujfalusi <peter.ujfalusi@...com>,
	Vinod Koul <vinod.koul@...el.com>,
	Dan Williams <dan.j.williams@...el.com>,
	dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
	nsekhar@...com, linux-omap@...r.kernel.org,
	linux-serial@...r.kernel.org, john.ogness@...utronix.de
Subject: Re: [PATCH] dma: omap-dma: add support for pause of non-cyclic
 transfers

On Fri, Aug 07, 2015 at 12:36:14PM +0200, Sebastian Andrzej Siewior wrote:
> On 08/07/2015 11:44 AM, Peter Ujfalusi wrote:
> > with a short testing audio did not broke (the only user of pause/resume)
> > Some comments embedded.
> > 
> >> Cc: <stable@...r.kernel.org>
> > 
> > Why stable? This is not fixing any bugs since the PAUSE was not allowed for
> > non cyclic transfers.
> 
> Hmmm. The DRA7x was using pause before for UART. I just did not see it
> coming that it was not allowed here. John made a similar change to the
> edma driver and I assumed it went stable but now I see that it was just
> cherry-picked into the ti tree.

This is *NOT* stable material.

Pause of these channels is something that omap-dma has *never* supported.
Therefore, it is *not* a regression.  What you are doing is *adding* a
feature to the omap-dma driver.  That is not stable material in any sense.
Stable is for bug fixes to existing code, not feature enhancements.

If something else has been converted to pause channels and that is causing
a problem, then _that_ conversion is where the bug lies, not the lack of
support in the omap-dma.

If it's a result of using some new driver with omap-dma, then the problem
is with whatever introduced that new combination - it's not that omap-dma
is buggy.

Don't fix bugs in -stable by adding features.  That's _no_ way to fix bugs.

NAK on this feature patch having any kind of stable tag.

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