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

Wolfram Sang
2014-11-11T10:58:54Z

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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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