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SubjectRe: [RFC PATCH RESEND] i2c-piix4: Add Hygon Dhyana SMBus support
Hi Pu,

On Mon, 22 Apr 2019 21:10:07 +0800, Pu Wen wrote:
> The Hygon Dhyana CPU has the SMBus device with PCI device ID 0x790b,
> which is the same as AMD CZ SMBus device. So add Hygon Dhyana support
> to the i2c-piix4 driver by using the code path of AMD.

Sorry for the late answer.

> Cc: <stable@vger.kernel.org> # v5.0+

I object to adding this to stable. It's not fixing any bug, and it's
far from being a one-liner. I'd rather let distributions backport it as
they see fit.

> Signed-off-by: Pu Wen <puwen@hygon.cn>
> ---
> drivers/i2c/busses/i2c-piix4.c | 13 ++++++++++---
> 1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
> index 90946a8..9db9d9d 100644
> --- a/drivers/i2c/busses/i2c-piix4.c
> +++ b/drivers/i2c/busses/i2c-piix4.c
> @@ -289,6 +289,9 @@ static int piix4_setup_sb800(struct pci_dev *PIIX4_dev,
> PIIX4_dev->revision >= 0x41) ||
> (PIIX4_dev->vendor == PCI_VENDOR_ID_AMD &&
> PIIX4_dev->device == PCI_DEVICE_ID_AMD_KERNCZ_SMBUS &&
> + PIIX4_dev->revision >= 0x49) ||
> + (PIIX4_dev->vendor == PCI_VENDOR_ID_HYGON &&
> + PIIX4_dev->device == PCI_DEVICE_ID_AMD_KERNCZ_SMBUS &&
> PIIX4_dev->revision >= 0x49))
> smb_en = 0x00;

Does the compatibility with the original AMD chipset include the
revision number?

> else
> @@ -361,7 +364,8 @@ static int piix4_setup_sb800(struct pci_dev *PIIX4_dev,
> piix4_smba, i2ccfg >> 4);
>
> /* Find which register is used for port selection */
> - if (PIIX4_dev->vendor == PCI_VENDOR_ID_AMD) {
> + if (PIIX4_dev->vendor == PCI_VENDOR_ID_AMD ||
> + PIIX4_dev->vendor == PCI_VENDOR_ID_HYGON) {
> switch (PIIX4_dev->device) {
> case PCI_DEVICE_ID_AMD_KERNCZ_SMBUS:
> piix4_port_sel_sb800 = SB800_PIIX4_PORT_IDX_KERNCZ;
> @@ -794,6 +798,7 @@ static const struct pci_device_id piix4_ids[] = {
> { PCI_DEVICE(PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_SBX00_SMBUS) },
> { PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_HUDSON2_SMBUS) },
> { PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_KERNCZ_SMBUS) },
> + { PCI_DEVICE(PCI_VENDOR_ID_HYGON, PCI_DEVICE_ID_AMD_KERNCZ_SMBUS) },
> { PCI_DEVICE(PCI_VENDOR_ID_SERVERWORKS,
> PCI_DEVICE_ID_SERVERWORKS_OSB4) },
> { PCI_DEVICE(PCI_VENDOR_ID_SERVERWORKS,
> @@ -904,11 +909,13 @@ static int piix4_probe(struct pci_dev *dev, const struct pci_device_id *id)
> if ((dev->vendor == PCI_VENDOR_ID_ATI &&
> dev->device == PCI_DEVICE_ID_ATI_SBX00_SMBUS &&
> dev->revision >= 0x40) ||
> - dev->vendor == PCI_VENDOR_ID_AMD) {
> + dev->vendor == PCI_VENDOR_ID_AMD ||
> + dev->vendor == PCI_VENDOR_ID_HYGON) {
> bool notify_imc = false;
> is_sb800 = true;
>
> - if (dev->vendor == PCI_VENDOR_ID_AMD &&
> + if ((dev->vendor == PCI_VENDOR_ID_AMD ||
> + dev->vendor == PCI_VENDOR_ID_HYGON) &&
> dev->device == PCI_DEVICE_ID_AMD_KERNCZ_SMBUS) {
> u8 imc;
>

Patch looks good. I assume you have tested it on real hardware?

I would like you to also document the new supported chipset in
drivers/i2c/busses/Kconfig and Documentation/i2c/busses/i2c-piix4 as
well as in the header comment of i2c-piix4.c itself. I know it seems
redundant but it helps the user know which driver they need.

Thanks,
--
Jean Delvare
SUSE L3 Support

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