1 comment:
Patch Set #2, Line 11: BUG=b:124197348
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See comment3 below. for scenario 2, need setting GPP_B4 to low in S5. Thanks.
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Please refer to the attached photos for the power sequence requirement of LG touch screen .
scenario 1 : power on
Tuning the power sequence by hardware R/C delay as the attached circuit
The sequence spec : Vlcd must lead Vusb more than 60 ms .
scenario 2 : power off
Need firmware's help to turn off TS power by pulling low the "PCH_TS_EN" pin (GPP_B4) when received "power off" command .
The sequence spec : Vlcd must lag Vusb more than 0 ms .
scenario 3: sleep mode/suspend (S3)
In order to keep the system can be waked up by touch screen so must let Vusb be kept .
The firmware don't need to do anything for touch screen power during s3 .
The waveforms after tuning were attached as well , please have a look .
Blue color - Vusb
Yellow color - Vlcd
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