Re: [PATCH 3/4] i2c-i801: Check if interrupts are disabled

[Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>]

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On Mon, Nov 10, 2014 at 10:31:39PM +0100, Jean Delvare wrote:
> There is a control bit in the PCI configuration space which disables
> interrupts. If this bit is set, the driver should not try to make use
> of interrupts, it won't receive any.
> 
> Signed-off-by: Jean Delvare <jdelvare-l3A5Bk7waGM@public.gmane.org>
> Cc: Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>
> ---
>  drivers/i2c/busses/i2c-i801.c |   21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> --- linux-3.18-rc4.orig/drivers/i2c/busses/i2c-i801.c	2014-11-10 22:29:44.416991298 +0100
> +++ linux-3.18-rc4/drivers/i2c/busses/i2c-i801.c	2014-11-10 22:29:46.915045662 +0100
> @@ -110,12 +110,16 @@
>  
>  /* PCI Address Constants */
>  #define SMBBAR		4
> +#define SMBPCICTL	0x004
>  #define SMBPCISTS	0x006
>  #define SMBHSTCFG	0x040
>  
>  /* Host status bits for SMBPCISTS */
>  #define SMBPCISTS_INTS		0x08
>  
> +/* Control bits for SMBPCICTL */
> +#define SMBPCICTL_INTDIS	0x0400
> +
>  /* Host configuration bits for SMBHSTCFG */
>  #define SMBHSTCFG_HST_EN	1
>  #define SMBHSTCFG_SMB_SMI_EN	2
> @@ -1235,6 +1239,23 @@ static int i801_probe(struct pci_dev *de
>  	priv->adapter.timeout = HZ / 5;
>  
>  	if (priv->features & FEATURE_IRQ) {
> +		u16 pcictl, pcists;
> +
> +		/* Complain if an interrupt is already pending */
> +		pci_read_config_word(priv->pci_dev, SMBPCISTS, &pcists);
> +		if (pcists & SMBPCISTS_INTS)
> +			dev_warn(&dev->dev, "An interrupt is pending!\n");

You think it is better to not clear it?

> +
> +		/* Check if interrupts have been disabled */
> +		pci_read_config_word(priv->pci_dev, SMBPCICTL, &pcictl);
> +		if (pcictl & SMBPCICTL_INTDIS) {
> +			dev_warn(&dev->dev,
> +				 "Interrupts are disabled, will use polling\n");

I'd say it is more info than warning?

> +			priv->features &= ~FEATURE_IRQ;
> +		}
> +	}
> +
> +	if (priv->features & FEATURE_IRQ) {
>  		init_waitqueue_head(&priv->waitq);
>  
>  		err = request_irq(dev->irq, i801_isr, IRQF_SHARED,
> 
> -- 
> Jean Delvare
> SUSE L3 Support

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