RE: [PATCH v2 0/2] i2c:dw: Add APM X-Gene ACPI I2C device support

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Why/how can Linux driver make use of such non-ACPI defined methods?

Thanks,
Ivan

-----Original Message-----
From: Mika Westerberg [mailto:mika.westerberg@xxxxxxxxxxxxxxx] 
Sent: Wednesday, December 23, 2015 17:53
To: Xue, Ken
Cc: wsa@xxxxxxxxxxxxx; Suthikulpanit, Suravee; Loc Ho; rjw@xxxxxxxxxxxxx; lenb@xxxxxxxxxx; linux-i2c@xxxxxxxxxxxxxxx; linux-acpi@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; jcm@xxxxxxxxxx; patches@xxxxxxx; Hurwitz, Sherry; Duran, Leo; Hanjun Guo; Al Stone; Zheng, Ivan; Yu, Xiangliang
Subject: Re: [PATCH v2 0/2] i2c:dw: Add APM X-Gene ACPI I2C device support

On Wed, Dec 23, 2015 at 05:34:01PM +0800, Ken Xue wrote:
> 1) Regarding
> https://msdn.microsoft.com/en-us/library/windows/hardware/dn919852(v=v
> s.85).aspx , Window I2C driver should pass MITT test. There are 5 I2C 
> devices connect to one I2C bus for test. And those devices defined 
> different "ConnectionSpeed" over the I2C bus by ACPI resource 
> "I2CSerialBus".
> 
> During test, I2C bus should run in different "ConnectionSpeed" of 
> device.
> 
> That means windows driver can modify I2C bus speed to match the 
> "ConnectionSpeed" of device on-the-fly. Static value from SSCN and 
> FMCN can not work for WITT test cases.

That is why there are *CNT methods for all supported I2C modes:

  - SSCN() - returns for standard mode (100kHz)
  - FMCN() - returns for fast mode (400kHz)
  - FPCN() - returns for fast mode+ (1MHz)
 
for High-speed mode I'm not sure what the method name is ;-)

Then the Windows driver switches between those based on what the ConnectionSpeed is in the ACPI I2C connector.
--
To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux GPIO]     [Linux SPI]     [Linux Hardward Monitoring]     [LM Sensors]     [Linux USB Devel]     [Linux Media]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux