linux-kernel - Re: [PATCH v4 1/3] i2c: piix4: Fix port selection for AMD Family 16h Model 30h

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Date:   Tue, 20 Feb 2018 06:41:18 +1000
From:   Andrew Cooks <andrew.cooks@...ngear.com>
To:     Jean Delvare <jdelvare@...e.com>, Wolfram Sang <wsa@...-dreams.de>,
        "open list:I2C/SMBUS CONTROLLER DRIVERS FOR PC" 
        <linux-i2c@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 1/3] i2c: piix4: Fix port selection for AMD Family 16h
 Model 30h


Any comments?

On 31/01/18 07:40, Andrew Cooks wrote:
> Family 16h Model 30h SMBus controller has the same port selection
> register as described and fixed in commit 0fe16195f891
> ("i2c: piix4: Fix SMBus port selection for AMD Family 17h chips")
> 
> commit 6befa3fde65fe ("i2c: piix4: Support alternative port selection
> register") also fixed the port selection for Hudson2. Unfortunately the
> AMD naming and PCI Device IDs aren't particularly helpful here.
> 
> The SMBus port selection register is common to the following Families
> and models, as documented in AMD's publicly available BIOS and Kernel
> Developer Guides:
> 
>  50742 - Family 15h Model 60h-6Fh (PCI_DEVICE_ID_AMD_KERNCZ_SMBUS)
>  55072 - Family 15h Model 70h-7Fh (PCI_DEVICE_ID_AMD_KERNCZ_SMBUS)
>  52740 - Family 16h Model 30h-3Fh (PCI_DEVICE_ID_AMD_HUDSON2_SMBUS)
> 
> The Hudson2 PCI Device ID (PCI_DEVICE_ID_AMD_HUDSON2_SMBUS) is shared
> between Bolton FCH and Family 16h Model 30h, but the location of the
> SmBus0Sel port selection bits are different:
> 
>  51192 - Bolton Register Reference Guide
> 
> We distinguish between Bolton and Family 16h Model 30h using the PCI
> Revision ID:
> 
>   Bolton is device 0x780b, revision 0x15
>   Family 16h Model 30h is device 0x780b, revision 0x1F
>   Family 15h Model 60h and 70h are both device 0x790b, revision 0x4A.
> 
> The following additional public AMD BKDG documents were checked and do
> not share the same port selection register:
> 
>  42301 - Family 15h Model 00h-0Fh doesn't mention any
>  42300 - Family 15h Model 10h-1Fh doesn't mention any
>  49125 - Family 15h Model 30h-3Fh doesn't mention any
> 
>  48751 - Family 16h Model 00h-0Fh uses the previously supported
>          index register SB800_PIIX4_PORT_IDX_ALT at 0x2e
> 
> Signed-off-by: Andrew Cooks <andrew.cooks@...ngear.com>
> ---
>  drivers/i2c/busses/i2c-piix4.c | 12 +++++-------
>  1 file changed, 5 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
> index 174579d..5c90a44 100644
> --- a/drivers/i2c/busses/i2c-piix4.c
> +++ b/drivers/i2c/busses/i2c-piix4.c
> @@ -99,7 +99,7 @@
>  #define SB800_PIIX4_PORT_IDX_MASK	0x06
>  #define SB800_PIIX4_PORT_IDX_SHIFT	1
>  
> -/* On kerncz, SmBus0Sel is at bit 20:19 of PMx00 DecodeEn */
> +/* On kerncz and Hudson2, SmBus0Sel is at bit 20:19 of PMx00 DecodeEn */
>  #define SB800_PIIX4_PORT_IDX_KERNCZ		0x02
>  #define SB800_PIIX4_PORT_IDX_MASK_KERNCZ	0x18
>  #define SB800_PIIX4_PORT_IDX_SHIFT_KERNCZ	3
> @@ -359,18 +359,16 @@ static int piix4_setup_sb800(struct pci_dev *PIIX4_dev,
>  
>  	/* Find which register is used for port selection */
>  	if (PIIX4_dev->vendor == PCI_VENDOR_ID_AMD) {
> -		switch (PIIX4_dev->device) {
> -		case PCI_DEVICE_ID_AMD_KERNCZ_SMBUS:
> +		if ((PIIX4_dev->device == PCI_DEVICE_ID_AMD_KERNCZ_SMBUS) ||
> +		    (PIIX4_dev->device == PCI_DEVICE_ID_AMD_HUDSON2_SMBUS &&
> +			   PIIX4_dev->revision >= 0x1F)) {
>  			piix4_port_sel_sb800 = SB800_PIIX4_PORT_IDX_KERNCZ;
>  			piix4_port_mask_sb800 = SB800_PIIX4_PORT_IDX_MASK_KERNCZ;
>  			piix4_port_shift_sb800 = SB800_PIIX4_PORT_IDX_SHIFT_KERNCZ;
> -			break;
> -		case PCI_DEVICE_ID_AMD_HUDSON2_SMBUS:
> -		default:
> +		} else {
>  			piix4_port_sel_sb800 = SB800_PIIX4_PORT_IDX_ALT;
>  			piix4_port_mask_sb800 = SB800_PIIX4_PORT_IDX_MASK;
>  			piix4_port_shift_sb800 = SB800_PIIX4_PORT_IDX_SHIFT;
> -			break;
>  		}
>  	} else {
>  		mutex_lock(&piix4_mutex_sb800);
>