Re: [PATCH] can: mcp251xfd: mcp251xfd_open(): request IRQ as shared

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Sat, Jul 24, 2021 at 10:52:13PM +0200, Marc Kleine-Budde wrote:
> The driver's IRQ handler supports shared IRQs, so request a shared IRQ
> handler.
> 

I don't see any issue with the idea but I'd like to understand the requirement
for it. Usually the IRQ lines are shared when multiple devices use them
physically. For instance, a MFD device using a single GPIO for all of its
functions. But I don't see any sort of requirement like that here.

Making the IRQ lines shared will only induce latency IMO.

Thanks,
Mani

> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
> ---
>  drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
> index 90b06052549d..2b1e57552e1c 100644
> --- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
> +++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
> @@ -2527,8 +2527,8 @@ static int mcp251xfd_open(struct net_device *ndev)
>  	can_rx_offload_enable(&priv->offload);
>  
>  	err = request_threaded_irq(spi->irq, NULL, mcp251xfd_irq,
> -				   IRQF_ONESHOT, dev_name(&spi->dev),
> -				   priv);
> +				   IRQF_SHARED | IRQF_ONESHOT,
> +				   dev_name(&spi->dev), priv);
>  	if (err)
>  		goto out_can_rx_offload_disable;
>  
> -- 
> 2.30.2
> 
>