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

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Message-ID: <AM6PR04MB63411FDF5208C591AC9D010BE7A59@AM6PR04MB6341.eurprd04.prod.outlook.com>
Date:   Tue, 7 Jun 2022 01:49:15 +0000
From:   Ming Qian <ming.qian@....com>
To:     "Mirela Rabulea (OSS)" <mirela.rabulea@....nxp.com>,
        "mchehab@...nel.org" <mchehab@...nel.org>,
        "hverkuil-cisco@...all.nl" <hverkuil-cisco@...all.nl>
CC:     "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        dl-linux-imx <linux-imx@....com>,
        "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: RE: [PATCH v2] media: imx-jpeg: Disable some unused interrupt

> From: Mirela Rabulea (OSS) <mirela.rabulea@....nxp.com>
> Sent: 2022年6月6日 17:41
> To: Ming Qian <ming.qian@....com>; mchehab@...nel.org;
> hverkuil-cisco@...all.nl
> Cc: shawnguo@...nel.org; s.hauer@...gutronix.de; kernel@...gutronix.de;
> festevam@...il.com; dl-linux-imx <linux-imx@....com>;
> linux-media@...r.kernel.org; linux-kernel@...r.kernel.org;
> devicetree@...r.kernel.org; linux-arm-kernel@...ts.infradead.org
> Subject: Re: [PATCH v2] media: imx-jpeg: Disable some unused interrupt
> 
> 
> 
> On 06.06.2022 05:33, Ming Qian wrote:
> >> From: Mirela Rabulea (OSS) <mirela.rabulea@....nxp.com>
> >> Sent: 2022年6月6日 0:43
> >> To: Ming Qian <ming.qian@....com>; mchehab@...nel.org;
> >> hverkuil-cisco@...all.nl
> >> Cc: shawnguo@...nel.org; s.hauer@...gutronix.de;
> >> kernel@...gutronix.de; festevam@...il.com; dl-linux-imx
> >> <linux-imx@....com>; linux-media@...r.kernel.org;
> >> linux-kernel@...r.kernel.org; devicetree@...r.kernel.org;
> >> linux-arm-kernel@...ts.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@....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?
> 
> 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
> 

OK, I'll make another patch that disable slot interrupt when frame done, and clean the code.

> >
> > 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)