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

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Date:   Tue, 7 Jun 2022 07:26:26 +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

This patch can be superseded now.
It was replaced by another patch https://patchwork.linuxtv.org/project/linux-media/patch/20220607072315.23209-1-ming.qian@nxp.com/


> From: Ming Qian
> Sent: 2022年6月7日 9:49
> To: Mirela Rabulea (OSS) <mirela.rabulea@....nxp.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
> 
> > 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)