From 8f78df90d84acd7a0b22c2b44a258421063a972f Mon Sep 17 00:00:00 2001 From: Imre Deak Date: Tue, 20 Nov 2018 11:23:25 +0200 Subject: [PATCH] drm/i915: Add code comment on assumption of pipe==transcoder MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Cc: Lucas De Marchi Cc: Mika Kahola Signed-off-by: Imre Deak Reviewed-by: Ville Syrjälä (v2) Link: https://patchwork.freedesktop.org/patch/msgid/20181120092325.21249-3-imre.deak@intel.com --- 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, -- 2.30.2