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
