RE: [PATCH v2] media: imx-jpeg: Disable some unused interrupt

[Ming Qian <ming.qian@nxp.com>]

> From: Mirela Rabulea (OSS) <mirela.rabulea@oss.nxp.com>
> Sent: 2022年6月6日 0:43
> To: Ming Qian <ming.qian@nxp.com>; mchehab@kernel.org;
> hverkuil-cisco@xs4all.nl
> Cc: shawnguo@kernel.org; s.hauer@pengutronix.de; kernel@pengutronix.de;
> festevam@gmail.com; dl-linux-imx <linux-imx@nxp.com>;
> linux-media@vger.kernel.org; linux-kernel@vger.kernel.org;
> devicetree@vger.kernel.org; linux-arm-kernel@lists.infradead.org
> Subject: Re: [PATCH v2] media: imx-jpeg: Disable some unused interrupt
> 
> Hi Ming,
> 
> On 30.05.2022 10:47, Ming Qian wrote:
> > The interrupt STMBUF_HALF may be triggered after frame done.
> > It may led to system hang if driver try to access the register after
> > power off.
> > And interrupt STMBUF_HALF and STMBUF_RTND have no other effect.
> > So disable them and the unused interrupts.
> >
> > Fixes: 2db16c6ed72ce ("media: imx-jpeg: Add V4L2 driver for i.MX8 JPEG
> > Encoder/Decoder")
> > Signed-off-by: Ming Qian <ming.qian@nxp.com>
> > ---
> > v2
> > - add Fixes tag
> >   drivers/media/platform/nxp/imx-jpeg/mxc-jpeg-hw.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg-hw.c
> > b/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg-hw.c
> > index c482228262a3..258fbee7ab66 100644
> > --- a/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg-hw.c
> > +++ b/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg-hw.c
> > @@ -76,7 +76,7 @@ void print_wrapper_info(struct device *dev, void
> > __iomem *reg)
> >
> >   void mxc_jpeg_enable_irq(void __iomem *reg, int slot)
> >   {
> > -	writel(0xFFFFFFFF, reg + MXC_SLOT_OFFSET(slot, SLOT_IRQ_EN));
> > +	writel(0xF0C, reg + MXC_SLOT_OFFSET(slot, SLOT_IRQ_EN));
> 
> There is another way, less aggressive, to go around this, disable all the
> interrupts once FRMDONE is received (or some other error condition),
> interrupts will get re-enabled at the next device_run. I checked this works, in
> mxc_jpeg_dec_irq:
> buffers_done:
> 	writel(0x0, reg + MXC_SLOT_OFFSET(slot, SLOT_IRQ_EN));
> 

Hi Mirela,

Yes, I think it should work if we disable slot interrupt when frame done.
And which solution do you prefer?

Ming

> Either way, I would also replace this:
> 	if (!ctx) {
> 		dev_err(dev,
> 			"Instance released before the end of transaction.\n");
> 		/* soft reset only resets internal state, not registers */
> 		mxc_jpeg_sw_reset(reg);
> 		/* clear all interrupts */
> 		writel(0xFFFFFFFF, reg + MXC_SLOT_OFFSET(slot, SLOT_STATUS));
> 		goto job_unlock;
> 	}
> 
> With something like:
> BUG_ON(!ctx)
> 
> The initial intent of this code was to cope with the same problem,
> STMBUF_HALF interrupt received after FRMDONE, which could not be cleared,
> but it was not done right, I can see the hang in some rare cases. We should not
> run into it anymore, with interrupts disabled, either the way you proposed, or
> mine.
> 
> Regards,
> Mirela
> 
> >   }
> >
> >   void mxc_jpeg_sw_reset(void __iomem *reg)