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

[mirela.rabulea@xxxxxxxxxxx]

On 06.06.2022 05:33, Ming Qian wrote:
> > From: Mirela Rabulea (OSS) <mirela.rabulea@xxxxxxxxxxx>
> > Sent: 2022年6月6日 0:43
> > To: Ming Qian <ming.qian@xxxxxxx>; mchehab@xxxxxxxxxx;
> > hverkuil-cisco@xxxxxxxxx
> > Cc: shawnguo@xxxxxxxxxx; s.hauer@xxxxxxxxxxxxxx; kernel@xxxxxxxxxxxxxx;
> > festevam@xxxxxxxxx; dl-linux-imx <linux-imx@xxxxxxx>;
> > linux-media@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> > devicetree@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> > 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@xxxxxxx>
> > > ---
> > > 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?

Hi Ming, I don't have a strong preference, but just in case we decide to 
later use some of these interrupts, I would suggest to go with the 
disabling after FRMDONE.

Please do not forget to clean the other code related to "Instance 
released before the end of transaction".

Thanks,
Mirela

> 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)