Re: [PATCH 3/4] media: rkisp1: Fix IRQ handling due to shared interrupts

[Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>]

On 05/12/2023 10:20, Laurent Pinchart wrote:
> Hi Tomi,
> 
> Thank you for the patch.
> 
> On Tue, Dec 05, 2023 at 10:09:34AM +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.
> 
> Is IRQF_SHARED actually needed ?

I don't have any answer to that, but it seems to have always been there. 
Dropping it would simplify the code, but we can only do that if we are 
sure all the platforms the ISP is used on or will be used on won't share 
the interrupt.

  Tomi

>> 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@ideasonboard.com>
>> ---
>>   .../media/platform/rockchip/rkisp1/rkisp1-capture.c |  3 +++
>>   .../media/platform/rockchip/rkisp1/rkisp1-common.h  |  2 ++
>>   drivers/media/platform/rockchip/rkisp1/rkisp1-csi.c |  3 +++
>>   drivers/media/platform/rockchip/rkisp1/rkisp1-dev.c | 21 +++++++++++++++++++++
>>   drivers/media/platform/rockchip/rkisp1/rkisp1-isp.c |  3 +++
>>   5 files changed, 32 insertions(+)
>>
>> diff --git a/drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c b/drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c
>> index b50b044d22af..e92067897f28 100644
>> --- a/drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c
>> +++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c
>> @@ -779,6 +779,9 @@ irqreturn_t rkisp1_capture_isr(int irq, void *ctx)
>>   	unsigned int i;
>>   	u32 status;
>>   
>> +	if (!rkisp1->irqs_enabled)
>> +		return IRQ_NONE;
>> +
>>   	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 ec28907d978e..7f97fdf6e24c 100644
>> --- a/drivers/media/platform/rockchip/rkisp1/rkisp1-common.h
>> +++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-common.h
>> @@ -465,6 +465,7 @@ 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;
>> @@ -488,6 +489,7 @@ 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 47f4353a1784..f6b54654b435 100644
>> --- a/drivers/media/platform/rockchip/rkisp1/rkisp1-csi.c
>> +++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-csi.c
>> @@ -184,6 +184,9 @@ 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 1d60f4b8bd09..fbe03f7864e3 100644
>> --- a/drivers/media/platform/rockchip/rkisp1/rkisp1-dev.c
>> +++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-dev.c
>> @@ -306,6 +306,23 @@ 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 i = 0; i < RKISP1_NUM_IRQS; ++i) {
>> +		if (rkisp1->irqs[i] == -1)
>> +			continue;
>> +
>> +		if (i == 0 || rkisp1->irqs[i - 1] != rkisp1->irqs[i])
>> +			synchronize_irq(rkisp1->irqs[i]);
>> +	}
>> +
>>   	clk_bulk_disable_unprepare(rkisp1->clk_size, rkisp1->clks);
>>   	return pinctrl_pm_select_sleep_state(dev);
>>   }
>> @@ -322,6 +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 dafbfd230542..d6b8786661ad 100644
>> --- a/drivers/media/platform/rockchip/rkisp1/rkisp1-isp.c
>> +++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-isp.c
>> @@ -1082,6 +1082,9 @@ 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;
>