[Intel-gfx] bisected: i915 modeset broken in ac9b8236551d1177fd07b56aef9b565d1864420d

Meelis Roos mroos at linux.ee
Thu Jan 7 03:10:22 PST 2016

> > intel_setup_gmbus registers the i2c adapters, which does transfers on
> > the i2c bus on probe, and this happens before intel_power_domains_init
> > which initializes the power domain lock.
> >
> > The bisect and backtrace make sense and are not mysterious at all.
> >
> > Not sure of the fix though, are we better off changing the init order,
> > or making sure the probes don't happen or don't screw us up.
> So I started wondering why we are not seeing this. To reproduce, looks
> like you'll need to have an i2c driver with class I2C_CLASS_DDC for the
> i2c detect (and the bug) to happen. In tree, the only ones seem to be
> drivers/misc/eeprom/eeprom.c

Yes, I have that for DIMM SPD information access.

> drivers/staging/olpc_dcon/olpc_dcon.c
> I presume you have one or the other.
> No matter what, userspace can access the adapter right away when we
> register it, so this needs to be fixed along the lines of [1].
> BR,
> Jani.
> [1] http://patchwork.freedesktop.org/patch/msgid/1452157856-27360-1-git-send-email-daniel.vetter@ffwll.ch

Meelis Roos (mroos at linux.ee)

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