[Intel-gfx] [PATCH 05/14] drm/i915: Add a note explaining vdd on/off handling in intel_dp_aux_ch()

[Jani Nikula]

On Mon, 18 Aug 2014, ville.syrjala at linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> Add a comment to explain why we care about the current want_panel_vdd
> state in intel_dp_aux_ch().

Reviewed-by: Jani Nikula <jani.nikula at intel.com>


>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 30943a5..19a818f 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -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
> -- 
> 1.8.5.5
>
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-- 
Jani Nikula, Intel Open Source Technology Center