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Date: Wed, 10 Feb 2016 16:53:12 +0000
From: Lee Jones <lee.jones@...aro.org>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: "Rafael J . Wysocki" <rjw@...ysocki.net>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
linux-i2c@...r.kernel.org, linux-acpi@...r.kernel.org,
linux-kernel@...r.kernel.org,
Mika Westerberg <mika.westerberg@...ux.intel.com>,
Kevin Fenzi <kevin@...ye.com>, Arnd Bergmann <arnd@...db.de>,
Wolfram Sang <wsa@...-dreams.de>
Subject: Re: [PATCH v2 14/16] mfd: intel-lpss: Pass SDA hold time to I2C host
controller driver
On Mon, 30 Nov 2015, Andy Shevchenko wrote:
> From: Mika Westerberg <mika.westerberg@...ux.intel.com>
>
> Intel Skylake the LPSS I2C pad circuit has internal delays that require
> programming non-zero SDA hold time for the I2C host controller. If this is
> not done communication to slave devices may fail with arbitration lost
> errors like the one seen below taken from Lenovo Yoga 900:
>
> i2c_hid i2c-SYNA2B29:00: Fetching the HID descriptor
> i2c_hid i2c-SYNA2B29:00: __i2c_hid_command: cmd=20 00
> i2c_designware i2c_designware.1: i2c_dw_handle_tx_abort: lost arbitration
>
> To fix this we follow what the Windows driver is doing and pass the default
> SDA hold time of 230 ns to all Intel Skylake host controllers. This still
> allows the platform to override these values by passing special ACPI
> methods SSCN and FMCN.
>
> Reported-by: Kevin Fenzi <kevin@...ye.com>
> Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
> drivers/mfd/intel-lpss-acpi.c | 19 +++++++++++++++++--
> drivers/mfd/intel-lpss-pci.c | 31 +++++++++++++++++++++++--------
> 2 files changed, 40 insertions(+), 10 deletions(-)
Seems fine in principle.
Acked-by: Lee Jones <lee.jones@...aro.org>
> diff --git a/drivers/mfd/intel-lpss-acpi.c b/drivers/mfd/intel-lpss-acpi.c
> index b6fd904..06f00d6 100644
> --- a/drivers/mfd/intel-lpss-acpi.c
> +++ b/drivers/mfd/intel-lpss-acpi.c
> @@ -18,6 +18,7 @@
> #include <linux/pm.h>
> #include <linux/pm_runtime.h>
> #include <linux/platform_device.h>
> +#include <linux/property.h>
>
> #include "intel-lpss.h"
>
> @@ -25,6 +26,20 @@ static const struct intel_lpss_platform_info spt_info = {
> .clk_rate = 120000000,
> };
>
> +static struct property_entry spt_i2c_properties[] = {
> + PROPERTY_ENTRY_U32("i2c-sda-hold-time-ns", 230),
> + { },
> +};
> +
> +static struct property_set spt_i2c_pset = {
> + .properties = spt_i2c_properties,
> +};
> +
> +static const struct intel_lpss_platform_info spt_i2c_info = {
> + .clk_rate = 120000000,
> + .pset = &spt_i2c_pset,
> +};
> +
> static const struct intel_lpss_platform_info bxt_info = {
> .clk_rate = 100000000,
> };
> @@ -35,8 +50,8 @@ static const struct intel_lpss_platform_info bxt_i2c_info = {
>
> static const struct acpi_device_id intel_lpss_acpi_ids[] = {
> /* SPT */
> - { "INT3446", (kernel_ulong_t)&spt_info },
> - { "INT3447", (kernel_ulong_t)&spt_info },
> + { "INT3446", (kernel_ulong_t)&spt_i2c_info },
> + { "INT3447", (kernel_ulong_t)&spt_i2c_info },
> /* BXT */
> { "80860AAC", (kernel_ulong_t)&bxt_i2c_info },
> { "80860ABC", (kernel_ulong_t)&bxt_info },
> diff --git a/drivers/mfd/intel-lpss-pci.c b/drivers/mfd/intel-lpss-pci.c
> index 5bfdfcc..a677480 100644
> --- a/drivers/mfd/intel-lpss-pci.c
> +++ b/drivers/mfd/intel-lpss-pci.c
> @@ -17,6 +17,7 @@
> #include <linux/pci.h>
> #include <linux/pm.h>
> #include <linux/pm_runtime.h>
> +#include <linux/property.h>
>
> #include "intel-lpss.h"
>
> @@ -65,6 +66,20 @@ static const struct intel_lpss_platform_info spt_info = {
> .clk_rate = 120000000,
> };
>
> +static struct property_entry spt_i2c_properties[] = {
> + PROPERTY_ENTRY_U32("i2c-sda-hold-time-ns", 230),
> + { },
> +};
> +
> +static struct property_set spt_i2c_pset = {
> + .properties = spt_i2c_properties,
> +};
> +
> +static const struct intel_lpss_platform_info spt_i2c_info = {
> + .clk_rate = 120000000,
> + .pset = &spt_i2c_pset,
> +};
> +
> static const struct intel_lpss_platform_info spt_uart_info = {
> .clk_rate = 120000000,
> .clk_con_id = "baudclk",
> @@ -121,20 +136,20 @@ static const struct pci_device_id intel_lpss_pci_ids[] = {
> { PCI_VDEVICE(INTEL, 0x9d28), (kernel_ulong_t)&spt_uart_info },
> { PCI_VDEVICE(INTEL, 0x9d29), (kernel_ulong_t)&spt_info },
> { PCI_VDEVICE(INTEL, 0x9d2a), (kernel_ulong_t)&spt_info },
> - { PCI_VDEVICE(INTEL, 0x9d60), (kernel_ulong_t)&spt_info },
> - { PCI_VDEVICE(INTEL, 0x9d61), (kernel_ulong_t)&spt_info },
> - { PCI_VDEVICE(INTEL, 0x9d62), (kernel_ulong_t)&spt_info },
> - { PCI_VDEVICE(INTEL, 0x9d63), (kernel_ulong_t)&spt_info },
> - { PCI_VDEVICE(INTEL, 0x9d64), (kernel_ulong_t)&spt_info },
> - { PCI_VDEVICE(INTEL, 0x9d65), (kernel_ulong_t)&spt_info },
> + { PCI_VDEVICE(INTEL, 0x9d60), (kernel_ulong_t)&spt_i2c_info },
> + { PCI_VDEVICE(INTEL, 0x9d61), (kernel_ulong_t)&spt_i2c_info },
> + { PCI_VDEVICE(INTEL, 0x9d62), (kernel_ulong_t)&spt_i2c_info },
> + { PCI_VDEVICE(INTEL, 0x9d63), (kernel_ulong_t)&spt_i2c_info },
> + { PCI_VDEVICE(INTEL, 0x9d64), (kernel_ulong_t)&spt_i2c_info },
> + { PCI_VDEVICE(INTEL, 0x9d65), (kernel_ulong_t)&spt_i2c_info },
> { PCI_VDEVICE(INTEL, 0x9d66), (kernel_ulong_t)&spt_uart_info },
> /* SPT-H */
> { PCI_VDEVICE(INTEL, 0xa127), (kernel_ulong_t)&spt_uart_info },
> { PCI_VDEVICE(INTEL, 0xa128), (kernel_ulong_t)&spt_uart_info },
> { PCI_VDEVICE(INTEL, 0xa129), (kernel_ulong_t)&spt_info },
> { PCI_VDEVICE(INTEL, 0xa12a), (kernel_ulong_t)&spt_info },
> - { PCI_VDEVICE(INTEL, 0xa160), (kernel_ulong_t)&spt_info },
> - { PCI_VDEVICE(INTEL, 0xa161), (kernel_ulong_t)&spt_info },
> + { PCI_VDEVICE(INTEL, 0xa160), (kernel_ulong_t)&spt_i2c_info },
> + { PCI_VDEVICE(INTEL, 0xa161), (kernel_ulong_t)&spt_i2c_info },
> { PCI_VDEVICE(INTEL, 0xa166), (kernel_ulong_t)&spt_uart_info },
> { }
> };
--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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