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drm/i915: Add a note explaining vdd on/off handling in intel_dp_aux_ch()

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Add a comment to explain why we care about the current want_panel_vdd
state in intel_dp_aux_ch().

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Ville Syrjälä 2014-08-18 22:16:00 +03:00 committed by Daniel Vetter
parent 1e0560e05d
commit 72c3500ac4
1 changed files with 6 additions and 0 deletions
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6
drivers/gpu/drm/i915/intel_dp.c
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@ -533,6 +533,12 @@ intel_dp_aux_ch(struct intel_dp *intel_dp,
bool has_aux_irq = HAS_AUX_IRQ(dev);
bool vdd;
/*
* We will be called with VDD already enabled for dpcd/edid/oui reads.
* In such cases we want to leave VDD enabled and it's up to upper layers
* to turn it off. But for eg. i2c-dev access we need to turn it on/off
* ourselves.
*/
vdd = edp_panel_vdd_on(intel_dp);
/* dp aux is extremely sensitive to irq latency, hence request the