linux-kernel - Re: [PATCH] arm pl011 serial: support multi-irq request

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Date:   Tue, 29 Jun 2021 08:18:59 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Bing Fan <hptsfb@...il.com>
Cc:     linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm pl011 serial: support multi-irq request

On Tue, Jun 29, 2021 at 09:29:24AM +0800, Bing Fan wrote:
> From: Bing Fan <tombinfan@...cent.com>
> 
> In order to make pl011 work better, multiple interrupts are
> required, such as TXIM, RXIM, RTIM, error interrupt(FE/PE/BE/OE);
> at the same time, pl011 to GIC does not merge the interrupt
> lines(each serial-interrupt corresponding to different GIC hardware
> interrupt), so need to enable and request multiple gic interrupt
> numbers in the driver.
> 
> Signed-off-by: Bing Fan <tombinfan@...cent.com>
> ---
>  drivers/tty/serial/amba-pl011.c | 23 ++++++++++++++++++++++-
>  1 file changed, 22 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
> index 78682c12156a..b63164e89903 100644
> --- a/drivers/tty/serial/amba-pl011.c
> +++ b/drivers/tty/serial/amba-pl011.c
> @@ -1703,9 +1703,30 @@ static void pl011_write_lcr_h(struct uart_amba_port *uap, unsigned int lcr_h)
>  
>  static int pl011_allocate_irq(struct uart_amba_port *uap)
>  {
> +	int ret = -1;

Pick a real error value.

> +	int i = 0;

Why is this initialized?

> +	unsigned int virq = 0;

Why is this initialized?

> +	struct amba_device *amba_dev = (struct amba_device *)uap->port.dev;

Are you sure you can just cast this like this?  Did you test this?

> +
> +	if (!amba_dev)
> +		return -1;

Do not make up error numbers, return a specific -ERR* value.

And how can this happen?

> +
>  	pl011_write(uap->im, uap, REG_IMSC);
>  
> -	return request_irq(uap->port.irq, pl011_int, IRQF_SHARED, "uart-pl011", uap);
> +	for (i = 0; i < AMBA_NR_IRQS; i++) {
> +		virq = amba_dev->irq[i];
> +		if (virq == 0)
> +			break;
> +
> +		ret = request_irq(virq, pl011_int, IRQF_SHARED, "uart-pl011-*", uap);
> +		if (ret < 0) {
> +			dev_info(uap->port.dev, "%s %d request %u interrupt failed\n",
> +					__func__, __LINE__, virq);

dev_err() is for errors, not dev_info().

And no need for __func__ and __LINE__ for the dev_* calls.



> +			break;
> +		}
> +	}
> +
> +	return ret;
>  }
>  
>  /*
> -- 
> 2.17.1
>