[i2c] [PATCH] Enable PEC on ICH6+ SMBus

[Gaston, Jason D]

Have you tested with this patch?  My only concern is that the ICHx
datasheets specify conditions when the PEC bit should and should not be
set.

Example from ICH8 Datasheet: "The I2C Read command with the PEC_EN bit
set produces undefined results. Software must force both the PEC_EN and
AAC bit to 0 when running this command."

Thanks,

Jason



>-----Original Message-----
>From: Jean Delvare [mailto:khali at linux-fr.org]
>Sent: Monday, December 04, 2006 6:42 AM
>To: Gaston, Jason D
>Cc: Linux I2C
>Subject: [PATCH] Enable PEC on ICH6+ SMBus
>
>Hi Jason,
>
>While reviewing your patches that added support for the ICH9 SMBus to
>the i2c-i801 driver, I noticed that we do not currently enable PEC
>support for the ICH6 and later Intel chips. I see no good reason not to
>enable it (although the actual use of PEC in Linux is admittedly
>limited), so I propose the following patch. Is it OK with you?
>
>
>Enable PEC on recent Intel SMBus controllers (ICH6, ICH7, ICH8, ICH9
>and ESB2.)
>
>Signed-off-by: Jean Delvare <khali at linux-fr.org>
>---
> drivers/i2c/busses/i2c-i801.c |   16 ++++++++++++----
> 1 file changed, 12 insertions(+), 4 deletions(-)
>
>--- linux-2.6.19-git.orig/drivers/i2c/busses/i2c-i801.c
2006-12-03
>15:52:22.000000000 +0100
>+++ linux-2.6.19-git/drivers/i2c/busses/i2c-i801.c	2006-12-03
>17:05:00.000000000 +0100
>@@ -470,12 +470,20 @@
> 	int err;
>
> 	I801_dev = dev;
>-	if ((dev->device == PCI_DEVICE_ID_INTEL_82801DB_3) ||
>-	    (dev->device == PCI_DEVICE_ID_INTEL_82801EB_3) ||
>-	    (dev->device == PCI_DEVICE_ID_INTEL_ESB_4))
>+	switch (dev->device) {
>+	case PCI_DEVICE_ID_INTEL_82801DB_3:
>+	case PCI_DEVICE_ID_INTEL_82801EB_3:
>+	case PCI_DEVICE_ID_INTEL_ESB_4:
>+	case PCI_DEVICE_ID_INTEL_ICH6_16:
>+	case PCI_DEVICE_ID_INTEL_ICH7_17:
>+	case PCI_DEVICE_ID_INTEL_ESB2_17:
>+	case PCI_DEVICE_ID_INTEL_ICH8_5:
>+	case PCI_DEVICE_ID_INTEL_ICH9_6:
> 		isich4 = 1;
>-	else
>+		break;
>+	default:
> 		isich4 = 0;
>+	}
>
> 	err = pci_enable_device(dev);
> 	if (err) {
>
>
>--
>Jean Delvare