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[PATCH v2 2/6] i3c: dw: Use IRQF_SHARED flag for dw-i3c-master

Shyam Sundar S K posted 6 patches 1 month ago
There is a newer version of this series
[PATCH v2 2/6] i3c: dw: Use IRQF_SHARED flag for dw-i3c-master
Posted by Shyam Sundar S K 1 month ago 
On AMD platforms, the IRQ lines are shared between two instances of I3C.
Add IRQF_SHARED flag during the interrupt registration process.

Co-developed-by: Sanket Goswami <Sanket.Goswami@amd.com>
Signed-off-by: Sanket Goswami <Sanket.Goswami@amd.com>
Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
---
 drivers/i3c/master/dw-i3c-master.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i3c/master/dw-i3c-master.c b/drivers/i3c/master/dw-i3c-master.c
index 1a7c300b6d45..fd58a95ae1c3 100644
--- a/drivers/i3c/master/dw-i3c-master.c
+++ b/drivers/i3c/master/dw-i3c-master.c
@@ -1578,7 +1578,7 @@ int dw_i3c_common_probe(struct dw_i3c_master *master,
 	writel(INTR_ALL, master->regs + INTR_STATUS);
 	irq = platform_get_irq(pdev, 0);
 	ret = devm_request_irq(&pdev->dev, irq,
-			       dw_i3c_master_irq_handler, 0,
+			       dw_i3c_master_irq_handler, IRQF_SHARED,
 			       dev_name(&pdev->dev), master);
 	if (ret)
 		goto err_assert_rst;
-- 
2.34.1
Re: [PATCH v2 2/6] i3c: dw: Use IRQF_SHARED flag for dw-i3c-master
Posted by Jarkko Nikula 3 weeks ago 
On 10/23/24 8:51 AM, Shyam Sundar S K wrote:
> On AMD platforms, the IRQ lines are shared between two instances of I3C.
> Add IRQF_SHARED flag during the interrupt registration process.
> 
> Co-developed-by: Sanket Goswami <Sanket.Goswami@amd.com>
> Signed-off-by: Sanket Goswami <Sanket.Goswami@amd.com>
> Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
> ---
>   drivers/i3c/master/dw-i3c-master.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/i3c/master/dw-i3c-master.c b/drivers/i3c/master/dw-i3c-master.c
> index 1a7c300b6d45..fd58a95ae1c3 100644
> --- a/drivers/i3c/master/dw-i3c-master.c
> +++ b/drivers/i3c/master/dw-i3c-master.c
> @@ -1578,7 +1578,7 @@ int dw_i3c_common_probe(struct dw_i3c_master *master,
>   	writel(INTR_ALL, master->regs + INTR_STATUS);
>   	irq = platform_get_irq(pdev, 0);
>   	ret = devm_request_irq(&pdev->dev, irq,
> -			       dw_i3c_master_irq_handler, 0,
> +			       dw_i3c_master_irq_handler, IRQF_SHARED,
>   			       dev_name(&pdev->dev), master);

dw_i3c_master_irq_handler() seems to be otherwise ready for shared 
interrupts but reminded me it might have a similar issue than 
drivers/i2c/busses/i2c-designware-master.c had [1] because both are 
runtime PM managed.

To me it looks dw_i3c_master_irq_handler() may incorrectly process 
interrupt from other device if register reads return all bits one when 
device is suspended. Worth to check.

1. Commit cdbd2f169bf1 ("i2c: designware: Do not process interrupt when 
device is suspended")
Re: [PATCH v2 2/6] i3c: dw: Use IRQF_SHARED flag for dw-i3c-master
Posted by Shyam Sundar S K 2 weeks, 5 days ago 

On 11/4/2024 20:04, Jarkko Nikula wrote:
> On 10/23/24 8:51 AM, Shyam Sundar S K wrote:
>> On AMD platforms, the IRQ lines are shared between two instances of
>> I3C.
>> Add IRQF_SHARED flag during the interrupt registration process.
>>
>> Co-developed-by: Sanket Goswami <Sanket.Goswami@amd.com>
>> Signed-off-by: Sanket Goswami <Sanket.Goswami@amd.com>
>> Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
>> ---
>>   drivers/i3c/master/dw-i3c-master.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/i3c/master/dw-i3c-master.c
>> b/drivers/i3c/master/dw-i3c-master.c
>> index 1a7c300b6d45..fd58a95ae1c3 100644
>> --- a/drivers/i3c/master/dw-i3c-master.c
>> +++ b/drivers/i3c/master/dw-i3c-master.c
>> @@ -1578,7 +1578,7 @@ int dw_i3c_common_probe(struct dw_i3c_master
>> *master,
>>       writel(INTR_ALL, master->regs + INTR_STATUS);
>>       irq = platform_get_irq(pdev, 0);
>>       ret = devm_request_irq(&pdev->dev, irq,
>> -                   dw_i3c_master_irq_handler, 0,
>> +                   dw_i3c_master_irq_handler, IRQF_SHARED,
>>                      dev_name(&pdev->dev), master);
> 
> dw_i3c_master_irq_handler() seems to be otherwise ready for shared
> interrupts but reminded me it might have a similar issue than
> drivers/i2c/busses/i2c-designware-master.c had [1] because both are
> runtime PM managed.
> 
> To me it looks dw_i3c_master_irq_handler() may incorrectly process
> interrupt from other device if register reads return all bits one when
> device is suspended. Worth to check.
> 
> 1. Commit cdbd2f169bf1 ("i2c: designware: Do not process interrupt
> when device is suspended")

Makes sense. I will remove this change in the next revision.

Thanks,
Shyam

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