linux-kernel - Re: [PATCH] i801_smbus: clear SMBALERT status bit and disable SMBALERT interrupt

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Message-ID: <20190814161515.GB5816@kunai>
Date:   Wed, 14 Aug 2019 18:15:15 +0200
From:   Wolfram Sang <wsa@...-dreams.de>
To:     lingyxu <lingyan.xu@...ia-sbell.com>,
        Jean Delvare <jdelvare@...e.de>
Cc:     linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        Wladislav Wiebe <wladislav.wiebe@...ia.com>,
        Krzysztof Adamski <krzysztof.adamski@...ia.com>
Subject: Re: [PATCH] i801_smbus: clear SMBALERT status bit and disable
 SMBALERT interrupt

On Mon, Aug 12, 2019 at 10:40:34AM +0800, lingyxu wrote:
> From: Lingyan Xu <lingyan.xu@...ia-sbell.com>
> 
> In current i801 driver, SMBALERT interrupt is allowed
> (Slave Command Register bit2 is 0).
> But these is no handler for SMBALERT interrupt in i801_isr,
> if there is SMBALERT interrupt asserted and deasserted,
> i801 will have an irq flood for the related status bit is setted.
> 
> So SMBALERT interrupt handler is needed, and also, SMBALERT interrupt
> will be generated from time to time if slave chip have some fault.
> So disable SMBALERT interrupt is also needed.
> 
> About the solution,
> please see http://www.farnell.com/datasheets/1581967.pdf
> Page632 P640 for more.
> 
> Signed-off-by: Lingyan Xu <lingyan.xu@...ia-sbell.com>

Jean, this seems important if it fixes an interrupt flood. Can you
review, please?

> ---
>  drivers/i2c/busses/i2c-i801.c |    7 ++++++-
>  1 files changed, 6 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
> index f295693..033bafe 100644
> --- a/drivers/i2c/busses/i2c-i801.c
> +++ b/drivers/i2c/busses/i2c-i801.c
> @@ -661,9 +661,11 @@ static irqreturn_t i801_isr(int irq, void *dev_id)
>  	 * Clear irq sources and report transaction result.
>  	 * ->status must be cleared before the next transaction is started.
>  	 */
> +
> +	outb_p(status, SMBHSTSTS(priv));
> +
>  	status &= SMBHSTSTS_INTR | STATUS_ERROR_FLAGS;
>  	if (status) {
> -		outb_p(status, SMBHSTSTS(priv));
>  		priv->status = status;
>  		wake_up(&priv->waitq);
>  	}
> @@ -1810,6 +1812,9 @@ static int i801_probe(struct pci_dev *dev, const struct pci_device_id *id)
>  	/* Default timeout in interrupt mode: 200 ms */
>  	priv->adapter.timeout = HZ / 5;
>  
> +	/* Disable SMBALERT interrupt */
> +	outb_p(inb_p(SMBSLVCMD(priv)) | BIT(2), SMBSLVCMD(priv));
> +
>  	if (dev->irq == IRQ_NOTCONNECTED)
>  		priv->features &= ~FEATURE_IRQ;
>  
> -- 
> 1.7.1
> 

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