Re: [PATCH 2/2] media: rkisp1: Fix IRQ handling due to shared interrupts

[Laurent Pinchart]

Hi Tomi,

Thank you for the patch.

On Mon, Dec 18, 2023 at 09:54:01AM +0200, Tomi Valkeinen wrote:
> The driver requests the interrupts as IRQF_SHARED, so the interrupt
> handlers can be called at any time. If such a call happens while the ISP
> is powered down, the SoC will hang as the driver tries to access the
> ISP registers.
> 
> This can be reproduced even without the platform sharing the IRQ line:
> Enable CONFIG_DEBUG_SHIRQ and unload the driver, and the board will
> hang.
> 
> Fix this by adding a new field, 'irqs_enabled', which is used to bail
> out from the interrupt handler when the ISP is not operational.
> 
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
> ---
>  .../platform/rockchip/rkisp1/rkisp1-capture.c      |  3 +++
>  .../media/platform/rockchip/rkisp1/rkisp1-common.h |  2 ++
>  .../media/platform/rockchip/rkisp1/rkisp1-csi.c    |  3 +++
>  .../media/platform/rockchip/rkisp1/rkisp1-dev.c    | 22 ++++++++++++++++++++++
>  .../media/platform/rockchip/rkisp1/rkisp1-isp.c    |  3 +++
>  5 files changed, 33 insertions(+)
> 
> diff --git a/drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c b/drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c
> index aebd3c12020b..c381c22135a2 100644
> --- a/drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c
> +++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c
> @@ -725,6 +725,9 @@ irqreturn_t rkisp1_capture_isr(int irq, void *ctx)
>  	unsigned int i;
>  	u32 status;
>  
> +	if (!rkisp1->irqs_enabled)
> +		return IRQ_NONE;

Given that this is something all drivers that use shared IRQs have to
do, would it make sense to use a standard helper here, such as
pm_runtime_suspended() for instance ? I haven't looked at which one
would be the most appropriate (if any), there's also
pm_runtime_active() and pm_runtime_status_suspended(). That would
simplify this patch.

> +
>  	status = rkisp1_read(rkisp1, RKISP1_CIF_MI_MIS);
>  	if (!status)
>  		return IRQ_NONE;
> diff --git a/drivers/media/platform/rockchip/rkisp1/rkisp1-common.h b/drivers/media/platform/rockchip/rkisp1/rkisp1-common.h
> index 4b6b28c05b89..b757f75edecf 100644
> --- a/drivers/media/platform/rockchip/rkisp1/rkisp1-common.h
> +++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-common.h
> @@ -450,6 +450,7 @@ struct rkisp1_debug {
>   * @debug:	   debug params to be exposed on debugfs
>   * @info:	   version-specific ISP information
>   * @irqs:          IRQ line numbers
> + * @irqs_enabled:  the hardware is enabled and can cause interrupts
>   */
>  struct rkisp1_device {
>  	void __iomem *base_addr;
> @@ -471,6 +472,7 @@ struct rkisp1_device {
>  	struct rkisp1_debug debug;
>  	const struct rkisp1_info *info;
>  	int irqs[RKISP1_NUM_IRQS];
> +	bool irqs_enabled;
>  };
>  
>  /*
> diff --git a/drivers/media/platform/rockchip/rkisp1/rkisp1-csi.c b/drivers/media/platform/rockchip/rkisp1/rkisp1-csi.c
> index b6e47e2f1b94..4202642e0523 100644
> --- a/drivers/media/platform/rockchip/rkisp1/rkisp1-csi.c
> +++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-csi.c
> @@ -196,6 +196,9 @@ irqreturn_t rkisp1_csi_isr(int irq, void *ctx)
>  	struct rkisp1_device *rkisp1 = dev_get_drvdata(dev);
>  	u32 val, status;
>  
> +	if (!rkisp1->irqs_enabled)
> +		return IRQ_NONE;
> +
>  	status = rkisp1_read(rkisp1, RKISP1_CIF_MIPI_MIS);
>  	if (!status)
>  		return IRQ_NONE;
> diff --git a/drivers/media/platform/rockchip/rkisp1/rkisp1-dev.c b/drivers/media/platform/rockchip/rkisp1/rkisp1-dev.c
> index acc559652d6e..73cf08a74011 100644
> --- a/drivers/media/platform/rockchip/rkisp1/rkisp1-dev.c
> +++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-dev.c
> @@ -305,6 +305,24 @@ static int __maybe_unused rkisp1_runtime_suspend(struct device *dev)
>  {
>  	struct rkisp1_device *rkisp1 = dev_get_drvdata(dev);
>  
> +	rkisp1->irqs_enabled = false;
> +	/* Make sure the IRQ handler will see the above */
> +	mb();
> +
> +	/*
> +	 * Wait until any running IRQ handler has returned. The IRQ handler
> +	 * may get called even after this (as it's a shared interrupt line)
> +	 * but the 'irqs_enabled' flag will make the handler return immediately.
> +	 */
> +	for (unsigned int il = 0; il < ARRAY_SIZE(rkisp1->irqs); ++il) {
> +		if (rkisp1->irqs[il] == -1)
> +			continue;
> +
> +		/* Skip if the irq line is the same as previous */
> +		if (il == 0 || rkisp1->irqs[il - 1] != rkisp1->irqs[il])
> +			synchronize_irq(rkisp1->irqs[il]);
> +	}
> +
>  	clk_bulk_disable_unprepare(rkisp1->clk_size, rkisp1->clks);
>  	return pinctrl_pm_select_sleep_state(dev);
>  }
> @@ -321,6 +339,10 @@ static int __maybe_unused rkisp1_runtime_resume(struct device *dev)
>  	if (ret)
>  		return ret;
>  
> +	rkisp1->irqs_enabled = true;
> +	/* Make sure the IRQ handler will see the above */
> +	mb();
> +
>  	return 0;
>  }
>  
> diff --git a/drivers/media/platform/rockchip/rkisp1/rkisp1-isp.c b/drivers/media/platform/rockchip/rkisp1/rkisp1-isp.c
> index f00873d31c42..78a1f7a1499b 100644
> --- a/drivers/media/platform/rockchip/rkisp1/rkisp1-isp.c
> +++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-isp.c
> @@ -976,6 +976,9 @@ irqreturn_t rkisp1_isp_isr(int irq, void *ctx)
>  	struct rkisp1_device *rkisp1 = dev_get_drvdata(dev);
>  	u32 status, isp_err;
>  
> +	if (!rkisp1->irqs_enabled)
> +		return IRQ_NONE;
> +
>  	status = rkisp1_read(rkisp1, RKISP1_CIF_ISP_MIS);
>  	if (!status)
>  		return IRQ_NONE;

-- 
Regards,

Laurent Pinchart