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SubjectRe: [PATCH v2] media: imx-jpeg: Disable some unused interrupt
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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));

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)

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