[Bug 31339] HP/Compaq 8510w HDMI port only works when booted with monitor attached

bugzilla-daemon at freedesktop.org bugzilla-daemon at freedesktop.org
Fri Nov 5 11:43:11 PDT 2010


--- Comment #14 from Tyson Whitehead <twhitehead at gmail.com> 2010-11-05 11:43:10 PDT ---
Created an attachment (id=40073)
 View: https://bugs.freedesktop.org/attachment.cgi?id=40073
 Review: https://bugs.freedesktop.org/review?bug=31339&attachment=40073

Patch to add (likely) missing complements in masking operations used to update
DDC and clock/data mux

Hey Alex,

It seemed that this must be related to the DDC mux, so I had a quick look
through the code I2C mux code.  The masking operations seemed suspect as they
effectively did either

val &= 0x06  (ddc_mux_control_pin)
val |= 0x04  (ddc_mux_state)


val &= 0x06  (ddc_mux_control_pin)
val |= 0x02  (ddc_mux_state)

That really seemed like it should be

val &= 0xf9  (~ddc_mux_control_pin)
val |= 0x04  (ddc_mux_state)


val &= 0xf9  (~ddc_mux_control_pin)
val |= 0x02  (ddc_mux_state)

so I switched the masking to use the complements, and everything works now!

Thanks again for all your hard work on this.  It's great to finally have open
source drivers for a state-of-the-art video card.

Cheers!  -Tyson

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