ACK: [PATCH 1/1] mfd: intel-lpss: Fix Intel Cannon Lake LPSS I2C input clock

[Colin Ian King]

On 30/08/18 04:54, Kai-Heng Feng wrote:
> From: Jarkko Nikula <jarkko.nikula at linux.intel.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1789790
> 
> Intel Cannon Lake PCH has much higher 216 MHz input clock to LPSS I2C
> than Sunrisepoint which uses 120 MHz. Preliminary information was that
> both share the same clock rate but actual silicon implements elevated
> rate for better support for 3.4 MHz high-speed I2C.
> 
> This incorrect input clock rate results too high I2C bus clock in case
> ACPI doesn't provide tuned I2C timing parameters since I2C host
> controller driver calculates them from input clock rate.
> 
> Fix this by using the correct rate. We still share the same 230 ns SDA
> hold time value than Sunrisepoint.
> 
> Cc: stable at vger.kernel.org
> Fixes: b418bbff36dd ("mfd: intel-lpss: Add Intel Cannonlake PCI IDs")
> Reported-by: Jian-Hong Pan <jian-hong at endlessm.com>
> Reported-by: Chris Chiu <chiu at endlessm.com>
> Reported-by: Daniel Drake <drake at endlessm.com>
> Signed-off-by: Jarkko Nikula <jarkko.nikula at linux.intel.com>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko at linux.intel.com>
> Acked-by: Mika Westerberg <mika.westerberg at linux.intel.com>
> Tested-by: Jian-Hong Pan <jian-hong at endlessm.com>
> Signed-off-by: Lee Jones <lee.jones at linaro.org>
> (cherry picked from commit 4e93a658576ab115977225c9d0992b97ff19ba8c)
> Signed-off-by: Kai-Heng Feng <kai.heng.feng at canonical.com>
> ---
>  drivers/mfd/intel-lpss-pci.c | 25 +++++++++++++++----------
>  1 file changed, 15 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/mfd/intel-lpss-pci.c b/drivers/mfd/intel-lpss-pci.c
> index d1c46de89eb4..d9ae983095c5 100644
> --- a/drivers/mfd/intel-lpss-pci.c
> +++ b/drivers/mfd/intel-lpss-pci.c
> @@ -124,6 +124,11 @@ static const struct intel_lpss_platform_info apl_i2c_info = {
>  	.properties = apl_i2c_properties,
>  };
>  
> +static const struct intel_lpss_platform_info cnl_i2c_info = {
> +	.clk_rate = 216000000,
> +	.properties = spt_i2c_properties,
> +};
> +
>  static const struct pci_device_id intel_lpss_pci_ids[] = {
>  	/* BXT A-Step */
>  	{ PCI_VDEVICE(INTEL, 0x0aac), (kernel_ulong_t)&bxt_i2c_info },
> @@ -207,13 +212,13 @@ static const struct pci_device_id intel_lpss_pci_ids[] = {
>  	{ PCI_VDEVICE(INTEL, 0x9daa), (kernel_ulong_t)&spt_info },
>  	{ PCI_VDEVICE(INTEL, 0x9dab), (kernel_ulong_t)&spt_info },
>  	{ PCI_VDEVICE(INTEL, 0x9dfb), (kernel_ulong_t)&spt_info },
> -	{ PCI_VDEVICE(INTEL, 0x9dc5), (kernel_ulong_t)&spt_i2c_info },
> -	{ PCI_VDEVICE(INTEL, 0x9dc6), (kernel_ulong_t)&spt_i2c_info },
> +	{ PCI_VDEVICE(INTEL, 0x9dc5), (kernel_ulong_t)&cnl_i2c_info },
> +	{ PCI_VDEVICE(INTEL, 0x9dc6), (kernel_ulong_t)&cnl_i2c_info },
>  	{ PCI_VDEVICE(INTEL, 0x9dc7), (kernel_ulong_t)&spt_uart_info },
> -	{ PCI_VDEVICE(INTEL, 0x9de8), (kernel_ulong_t)&spt_i2c_info },
> -	{ PCI_VDEVICE(INTEL, 0x9de9), (kernel_ulong_t)&spt_i2c_info },
> -	{ PCI_VDEVICE(INTEL, 0x9dea), (kernel_ulong_t)&spt_i2c_info },
> -	{ PCI_VDEVICE(INTEL, 0x9deb), (kernel_ulong_t)&spt_i2c_info },
> +	{ PCI_VDEVICE(INTEL, 0x9de8), (kernel_ulong_t)&cnl_i2c_info },
> +	{ PCI_VDEVICE(INTEL, 0x9de9), (kernel_ulong_t)&cnl_i2c_info },
> +	{ PCI_VDEVICE(INTEL, 0x9dea), (kernel_ulong_t)&cnl_i2c_info },
> +	{ PCI_VDEVICE(INTEL, 0x9deb), (kernel_ulong_t)&cnl_i2c_info },
>  	/* SPT-H */
>  	{ PCI_VDEVICE(INTEL, 0xa127), (kernel_ulong_t)&spt_uart_info },
>  	{ PCI_VDEVICE(INTEL, 0xa128), (kernel_ulong_t)&spt_uart_info },
> @@ -240,10 +245,10 @@ static const struct pci_device_id intel_lpss_pci_ids[] = {
>  	{ PCI_VDEVICE(INTEL, 0xa32b), (kernel_ulong_t)&spt_info },
>  	{ PCI_VDEVICE(INTEL, 0xa37b), (kernel_ulong_t)&spt_info },
>  	{ PCI_VDEVICE(INTEL, 0xa347), (kernel_ulong_t)&spt_uart_info },
> -	{ PCI_VDEVICE(INTEL, 0xa368), (kernel_ulong_t)&spt_i2c_info },
> -	{ PCI_VDEVICE(INTEL, 0xa369), (kernel_ulong_t)&spt_i2c_info },
> -	{ PCI_VDEVICE(INTEL, 0xa36a), (kernel_ulong_t)&spt_i2c_info },
> -	{ PCI_VDEVICE(INTEL, 0xa36b), (kernel_ulong_t)&spt_i2c_info },
> +	{ PCI_VDEVICE(INTEL, 0xa368), (kernel_ulong_t)&cnl_i2c_info },
> +	{ PCI_VDEVICE(INTEL, 0xa369), (kernel_ulong_t)&cnl_i2c_info },
> +	{ PCI_VDEVICE(INTEL, 0xa36a), (kernel_ulong_t)&cnl_i2c_info },
> +	{ PCI_VDEVICE(INTEL, 0xa36b), (kernel_ulong_t)&cnl_i2c_info },
>  	{ }
>  };
>  MODULE_DEVICE_TABLE(pci, intel_lpss_pci_ids);
> 

Is from upstream and in stable, limited set of devices affected,
regression potential seems low, so..

Acked-by: Colin Ian King <colin.king at canonical.com>