linux-kernel - Re: [PATCH] dmaengine: xgene-dma: Fix double IRQ issue by setting IRQ_DISABLE

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Date:	Thu, 7 Jan 2016 10:19:09 +0530
From:	Vinod Koul <vinod.koul@...el.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Rameshwar Sahu <rsahu@....com>, dan.j.williams@...el.com,
	dmaengine@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, jcm@...hat.com,
	patches@....com, Kaustubh Gondkar <kgondkar@....com>
Subject: Re: [PATCH] dmaengine: xgene-dma: Fix double IRQ issue by setting
 IRQ_DISABLE_UNLAZY flag

On Wed, Jan 06, 2016 at 11:05:02AM +0100, Thomas Gleixner wrote:
> On Wed, 6 Jan 2016, Vinod Koul wrote:
> > On Wed, Jan 06, 2016 at 02:51:07PM +0530, Rameshwar Sahu wrote:
> > > >> @@ -1610,6 +1611,7 @@ static int xgene_dma_request_irqs(struct xgene_dma *pdma)
> > > >>       /* Register DMA channel rx irq */
> > > >>       for (i = 0; i < XGENE_DMA_MAX_CHANNEL; i++) {
> > > >>               chan = &pdma->chan[i];
> > > >> +             irq_set_status_flags(chan->rx_irq, IRQ_DISABLE_UNLAZY);
> > > >
> > > > Why not use irq_settings_disable_unlazy(), at least read the reference you
> > > > pointed out!
> > > 
> > > irq_settings_disable_unlazy() is helper function to test
> > > IRQ_DISABLE_UNLAZY flag is set or not, it's not for setting this flag.
> > > FYI...
> > > +static inline bool irq_settings_disable_unlazy(struct irq_desc *desc)
> > > +{
> > > + return desc->status_use_accessors & _IRQ_DISABLE_UNLAZY;
> > > +}
> > 
> > Ah yes, I saw clear API and assumed there would be set. Then I think we
> > should add a set helper as well as the usage is intended for drivers to
> > set this flag
> > 
> > Thomas,
> > 
> > Any reason why you didn't add a set helper, only test and clear?
> 
> Why would I? Those helpers are core internal and not usable in random drivers.
> 
> Drivers have irq_set_status_flags()/irq_clear_status_flags() ...

The effect of irq_set_status_flags(irq, IRQ_DISABLE_UNLAZY) is same as
providing a helper. If your recommendation is to use this by driver then I
am find with the approach too

Thanks
-- 
~Vinod
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