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

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Message-ID: <9eb7c88a-c448-45cc-aeaa-88ab59cdadc5@linux.intel.com>
Date: Mon, 4 Nov 2024 16:34:22 +0200
From: Jarkko Nikula <jarkko.nikula@...ux.intel.com>
To: Shyam Sundar S K <Shyam-sundar.S-k@....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 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")