Re: [PATCH v2 2/2] i2c: designware: Disable pm for PMIC i2c-bus even if there is no _SEM method

[Jarkko Nikula <jarkko.nikula@linux.intel.com>]

On 03/09/17 17:00, Jarkko Nikula wrote:
> + Tianyu
>
> On 03/08/17 10:47, Hans de Goede wrote:
>> Cherrytrail devices use the dw i2c-bus with uid 7 to access their PMIC.
>> Even if the i2c-bus to the PMIC is not shared with the SoC's P-Unit
>> and i2c-designware-baytrail.c thus does not set the pm_disabled flag,
>> we still need to disable pm so that ACPI PMIC opregions can access the
>> PMIC during late-suspend and early-resume.
>>
>> This fixes errors like these blocking suspend:
>>
>>   i2c_designware 808622C1:06: timeout waiting for bus ready
>>   ACPI Exception: AE_ERROR, Returned by Handler for [UserDefinedRegion]
>>   acpi 80860F14:02: Failed to change power state to D3hot
>>   PM: late suspend of devices failed
>>
>> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
>> ---
>>  drivers/i2c/busses/i2c-designware-platdrv.c | 15 +++++++++++++++
>>  1 file changed, 15 insertions(+)
>>
>> diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c
>> b/drivers/i2c/busses/i2c-designware-platdrv.c
>> index 8ed96dd..08d609e 100644
>> --- a/drivers/i2c/busses/i2c-designware-platdrv.c
>> +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
>> @@ -94,7 +94,10 @@ static void dw_i2c_acpi_params(struct
>> platform_device *pdev, char method[],
>>  static int dw_i2c_acpi_configure(struct platform_device *pdev)
>>  {
>>      struct dw_i2c_dev *dev = platform_get_drvdata(pdev);
>> +    acpi_handle handle = ACPI_HANDLE(&pdev->dev);
>>      const struct acpi_device_id *id;
>> +    struct acpi_device *adev;
>> +    const char *uid;
>>
>>      dev->adapter.nr = -1;
>>      dev->tx_fifo_depth = 32;
>> @@ -114,6 +117,18 @@ static int dw_i2c_acpi_configure(struct
>> platform_device *pdev)
>>      if (id && id->driver_data)
>>          dev->flags |= (u32)id->driver_data;
>>
>> +    if (acpi_bus_get_device(handle, &adev))
>> +        return -ENODEV;
>> +
>> +    /*
>> +     * Cherrytrail I2C7 gets used for the PMIC which gets accessed
>> +     * through ACPI opregions during late suspend / early resume
>> +     * disable pm for it.
>> +     */
>> +    uid = adev->pnp.unique_id;
>> +    if ((dev->flags & MODEL_CHERRYTRAIL) && !strcmp(uid, "7"))
>> +        dev->pm_disabled = true;
>> +
>
> I'm fine with this but wondering can this be detected any other way than
> hardcoded bus number.
>
> Tianyu: You are the author of 5d98e61d337c ("I2C/ACPI: Add i2c ACPI
> operation region support"). Do you know is there way to see is there a
> PMIC connected to the bus?
>
> Jarkko Nikula <jarkko.nikula@linux.intel.com>

Here too:

Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>