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Re: [Libreboot] X60 tablet: screen whine after 1400x1050 screen swap

From: Charles Devereaux
Subject: Re: [Libreboot] X60 tablet: screen whine after 1400x1050 screen swap
Date: Fri, 17 Apr 2015 21:29:50 -0400

I much prefer not having to flash non free software (and even after extracting and adding the vgarom based on and, I still can't read the value with devmem2 anyway - it always returns 0)

I flashed back free software and intel_reg gives the following:
gpu_hotplug = 0x00000220
gpu_lvds_use_spread_spectrum_clock = 1
gpu_lvds_is_dual_channel = 0
gpu_backlight = 0x879f87da
backlight modulation frequency = 180.016706 Hz
duty cycle = 100%
legacy backlight brightness = 0x83

About the intel_bios_reader, I passed the oprom_0.rom and got the attached output. Apparently it still thinks I have a type 2 (1024x768) panel instead of the1400x1050 (type 4 or 5) I installed.

None of the frequencies match. (180 vs 122 vs 162)

Previously, 0x879f879e gave the uneven backlight problem.
Using 0x79417940 everything works fine, but with a lesser whine -- yet gives me that 0x879f87da or 0x879f87e6 when I tweak the brightness

At this point I'm not sure what I should do. Any other suggestion is welcome.

On Thu, Apr 16, 2015 at 12:45 PM, Michał Masłowski <address@hidden> wrote:
> Just follow the same method, but on your X60 Tablet, and you read from
> 0xe4361254 location in devmem to get the proper value.

Don't recommend accessing fixed memory locations. reads it in a way
independent of where your system maps PCI regions.  (That script is
inefficient and has wrong comments.  I do not know proper tools for
doing exactly this in scripts.)

The intel_bios_reader program (in intel-gpu-tools) also prints the PWM
frequency from which the register value can be computed.

Attachment: oprom.txt
Description: Text document

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