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List:       linuxbios
Subject:    [coreboot] G505S - slightly different Voltages at integrated HD 8650G iGPU AtomBIOS ?
From:       Ivan Ivanov <qmastery16 () gmail ! com>
Date:       2019-02-27 14:51:18
Message-ID: CAAaskFC+oLTd7Ah34-1nyFU1W-7-O7Haw_PzBqrLszv-4fWWMg () mail ! gmail ! com
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Interesting discovery about the AtomBIOS files at " g505s-atombios "
repository - https://github.com/g505s-opensource-researcher/g505s-atombios
:

While there was the same "clean" proprietary UEFI image flashed both
to "G505S with HD 8570M" and to "G505S with R5 M230" before the
AtomBIOS extraction, their AtomBIOSes for _ integrated HD 8650G _
turned out as slightly different! (see sha256)

So I made their full disassembly with this AtomDis tool -
https://cgit.freedesktop.org/~mhopf/AtomDis/ , and compared, diff
results here - https://pastebin.com/eewzswnD . As you could see from
these diff results, for some reason "G505S R5 version" sets a slightly
higher voltages for its' integrated GPU :

compared to "G505S HD version" it is 1.8% - 3.2% higher if these 0x3e
/ 0x40 / 0x6e / 0x70 values are linear and 0x0 = 0 volts.
(usNBP0Voltage / usNBP1Voltage / usVoltageID )

What do you think: would it be okay to use the integrated VGA BIOS
obtained from "G505S R5 version" for "G505S HD version" ?
This voltage difference seems small enough and the integrated GPU is
the same part after all ---> I think that it should be fine.
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