drm/i915: Check error return when converting pipe to connector

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.

v2:
- Fall back to a reasonable default instead of bailing out in case of
  error. (Jani)
v3:
- Fix s/PIPE_INVALID/INVALID_PIPE/ typo. (Jani)
v4:
- Fix bogus bracing around WARN() condition. (Ville)

Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1494408113-379-5-git-send-email-imre.deak@intel.com

diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index cb50c52..c8103f8 100644 (file)
--- 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))
+               cpu_transcoder = intel_pipe_to_cpu_transcoder(dev_priv, pipe);
+       else
+               cpu_transcoder = TRANSCODER_EDP;
+
        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))
+               pipe = PIPE_A;
+
        ctl2 = I915_READ(BLC_PWM_CTL2);
        if (ctl2 & BLM_PWM_ENABLE) {
                DRM_DEBUG_KMS("backlight already enabled\n");
@@ -1037,6 +1044,9 @@ static void bxt_enable_backlight(struct intel_connector *connector)
        enum pipe pipe = intel_get_pipe_from_connector(connector);
        u32 pwm_ctl, val;
 
+       if (WARN_ON_ONCE(pipe == INVALID_PIPE))
+               pipe = PIPE_A;
+
        /* Controller 1 uses the utility pin. */
        if (panel->backlight.controller == 1) {
                val = I915_READ(UTIL_PIN_CTL);
@@ -1093,7 +1103,8 @@ void intel_panel_enable_backlight(struct intel_connector *connector)
        if (!panel->backlight.present)
                return;
 
-       DRM_DEBUG_KMS("pipe %c\n", pipe_name(pipe));
+       if (!WARN_ON_ONCE(pipe == INVALID_PIPE))
+               DRM_DEBUG_KMS("pipe %c\n", pipe_name(pipe));
 
        mutex_lock(&dev_priv->backlight_lock);