[Intel-gfx] [PATCH 5/8] drm/i915: Check error return when converting pipe to connector

[Jani Nikula]

On Wed, 26 Apr 2017, Imre Deak <imre.deak at intel.com> wrote:
> An error from intel_get_pipe_from_connector() would mean a bug somewhere
> else, but we still should check for it to prevent some other more
> obscure bug later.

Do check for invalid pipe, but please just limp on instead of bailing
out of the functions. See notes inline.

BR,
Jani.

>
> Signed-off-by: Imre Deak <imre.deak at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_panel.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
> index cb50c52..dbe05ec 100644
> --- a/drivers/gpu/drm/i915/intel_panel.c
> +++ b/drivers/gpu/drm/i915/intel_panel.c
> @@ -888,10 +888,14 @@ static void pch_enable_backlight(struct intel_connector *connector)
>  	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
>  	struct intel_panel *panel = &connector->panel;
>  	enum pipe pipe = intel_get_pipe_from_connector(connector);
> -	enum transcoder cpu_transcoder =
> -		intel_pipe_to_cpu_transcoder(dev_priv, pipe);
> +	enum transcoder cpu_transcoder;
>  	u32 cpu_ctl2, pch_ctl1, pch_ctl2;
>  
> +	if (WARN_ON_ONCE(pipe == INVALID_PIPE))
> +		return;

Please just assign e.g. TRANSCODER_EDP to cpu_transcoder in this case,
go on, and hope for the best. Do leave the warn in place though.

> +
> +	cpu_transcoder = intel_pipe_to_cpu_transcoder(dev_priv, pipe);
> +
>  	cpu_ctl2 = I915_READ(BLC_PWM_CPU_CTL2);
>  	if (cpu_ctl2 & BLM_PWM_ENABLE) {
>  		DRM_DEBUG_KMS("cpu backlight already enabled\n");
> @@ -973,6 +977,9 @@ static void i965_enable_backlight(struct intel_connector *connector)
>  	enum pipe pipe = intel_get_pipe_from_connector(connector);
>  	u32 ctl, ctl2, freq;
>  
> +	if (WARN_ON_ONCE(pipe == INVALID_PIPE))
> +		return;

Same here, please just assign e.g. PIPE_A here with the warning, and
limp on.

> +
>  	ctl2 = I915_READ(BLC_PWM_CTL2);
>  	if (ctl2 & BLM_PWM_ENABLE) {
>  		DRM_DEBUG_KMS("backlight already enabled\n");
> @@ -1093,6 +1100,9 @@ void intel_panel_enable_backlight(struct intel_connector *connector)
>  	if (!panel->backlight.present)
>  		return;
>  
> +	if (WARN_ON_ONCE(pipe == INVALID_PIPE))
> +		return;

Here, pipe is only used for the debug logging, just skip that instead.

> +
>  	DRM_DEBUG_KMS("pipe %c\n", pipe_name(pipe));
>  
>  	mutex_lock(&dev_priv->backlight_lock);

-- 
Jani Nikula, Intel Open Source Technology Center