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Update ROCK 5B PD parameters #117

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Update ROCK 5B PD parameters #117

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RadxaYuntian
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int-n-gpios is only supported in Rockchip U-Boot.

Signed-off-by: Yuntian Zhang <yt@radxa.com>
Signed-off-by: Yuntian Zhang <yt@radxa.com>
@RadxaStephen
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For ROCK 4, can you add another PR?

@amazingfate
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Why do we have to limit the voltage to 12V? We can reach up to 20V.

@amazingfate
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For ROCK 4, can you add another PR?

I think rock4's pd negotiation is not handled by kernel.

@RadxaYuntian
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Why do we have to limit the voltage to 12V? We can reach up to 20V.

That's true, but the hardware engineer suggest to reduce the maximum voltage to a lower value to improve efficiency.

I think rock4's pd negotiation is not handled by kernel.

Those are some minor fixes unrelated to PD: #118 .

@amazingfate
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This commit will limit the power supply of PD no higher than 36W(12V3A) because most PD power supplies only have current higher than 3A at voltage 20V. Here is the log from /sys/kernel/debug/usb/tcpm-4-0022 when I'm using my 65W lenovo PD power:

[    3.122864] PD RX, header: 0x53a1 [1]
[    3.122873]  PDO 0: type 0, 5000 mV, 3000 mA [E]
[    3.122881]  PDO 1: type 0, 9000 mV, 3000 mA []
[    3.122888]  PDO 2: type 0, 12000 mV, 3000 mA []
[    3.122895]  PDO 3: type 0, 15000 mV, 3000 mA []
[    3.122902]  PDO 4: type 0, 20000 mV, 3250 mA []
[    3.122907] state change SNK_WAIT_CAPABILITIES -> SNK_NEGOTIATE_CAPABILITIES [rev3 POWER_NEGOTIATION]
[    3.122918] Setting usb_comm capable false
[    3.122934] cc=2 cc1=5 cc2=0 vbus=0 vconn=sink polarity=0
[    3.122941] Requesting PDO 4: 20000 mV, 3250 mA

reduce the maximum voltage to a lower value to improve efficiency

Do you mean it will cost more power when transfering higher voltage? I think this is acceptable.

@RadxaYuntian
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Do you mean it will cost more power when transfering higher voltage? I think this is acceptable.

Transferring at a higher voltage actually reduce the line loss, which is why electricity are transferred in Mega-volts before converting to 220V/110V for home use. The efficiency improvement is happened at DC-to-DC conversion circuit.

@RadxaYuntian RadxaYuntian closed this by deleting the head repository Jun 1, 2023
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3 participants