linux-kernel - Re: [PATCH v2 2/6] i3c: dw: Use IRQF

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Message-ID: <4221120d-8859-4444-89c9-f1ada539c92b@amd.com>
Date: Wed, 6 Nov 2024 18:43:04 +0530
From: Shyam Sundar S K <Shyam-sundar.S-k@....com>
To: Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
 Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc: Sanket.Goswami@....com, linux-i3c@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/6] i3c: dw: Use IRQF_SHARED flag for dw-i3c-master



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@....com>
>> Signed-off-by: Sanket Goswami <Sanket.Goswami@....com>
>> Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@....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