Add a comment to the pipe and transcoder enum definitions about our
assumption in the code about enum values for pipes and transcoders
with a 1:1 transcoder -> pipe mapping.
v2:
- Clarify more what are the assumptions about the enum values. (Ville)
v3: (Lucas)
- s/->/ -> / so it looks less like pointer dereferencing.
- Use pipe enums as initializers in the transcoder enum definition.
Cc: Ville Syrjälä <ville.syrj...@linux.intel.com>
Cc: Lucas De Marchi <lucas.demar...@intel.com>
Cc: Mika Kahola <mika.kah...@intel.com>
Signed-off-by: Imre Deak <imre.d...@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrj...@linux.intel.com> (v2)
---
drivers/gpu/drm/i915/intel_display.h | 22 +++++++++++++++++++---
1 file changed, 19 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_display.h
b/drivers/gpu/drm/i915/intel_display.h
index 43eb4ebbcc35..5f2955b944da 100644
--- a/drivers/gpu/drm/i915/intel_display.h
+++ b/drivers/gpu/drm/i915/intel_display.h
@@ -43,6 +43,11 @@ enum i915_gpio {
GPIOM,
};
+/*
+ * Keep the pipe enum values fixed: the code assumes that PIPE_A=0, the
+ * rest have consecutive values and match the enum values of transcoders
+ * with a 1:1 transcoder -> pipe mapping.
+ */
enum pipe {
INVALID_PIPE = -1,
@@ -57,9 +62,20 @@ enum pipe {
#define pipe_name(p) ((p) + 'A')
enum transcoder {
- TRANSCODER_A = 0,
- TRANSCODER_B,
- TRANSCODER_C,
+ /*
+ * The following transcoders have a 1:1 transcoder -> pipe mapping,
+ * keep their values fixed: the code assumes that TRANSCODER_A=0, the
+ * rest have consecutive values and match the enum values of the pipes
+ * they map to.
+ */
+ TRANSCODER_A = PIPE_A,
+ TRANSCODER_B = PIPE_B,
+ TRANSCODER_C = PIPE_C,
+
+ /*
+ * The following transcoders can map to any pipe, their enum value
+ * doesn't need to stay fixed.
+ */
TRANSCODER_EDP,
TRANSCODER_DSI_0,
TRANSCODER_DSI_1,
--
2.13.2
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