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[1/4] drm/msm/dpu: document INTF_EDP/INTF_DP difference

Message ID 20220222062246.242577-2-dmitry.baryshkov@linaro.org
State Accepted
Commit 4a9fb91ac74028d85f96f4caf7097e3a1e3a7321
Headers show
Series drm/msm/dpu: clearly document INTF_DP vs INTF_EDP difference | expand

Commit Message

Dmitry Baryshkov Feb. 22, 2022, 6:22 a.m. UTC 
Based on the discussions on the mailing list, document enum
dpu_intf_type and it's controversial fields: INTF_DP and INTF_EDP.

INTF_EDP is used for older eDP interface found on msm8x74/msm8x84
INTF_DP is used for both eDP and DP interfaces handled by the msm/dp
driver. The DPU driver does not make a difference between them.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_hw_mdss.h | 8 ++++++++
 1 file changed, 8 insertions(+)
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Patch

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_mdss.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_mdss.h
index bb9ceadeb0bb..4f8336cc7911 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_mdss.h
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_mdss.h
@@ -205,12 +205,20 @@  enum dpu_intf {
 	INTF_MAX
 };
 
+/*
+ * Historically these values correspond to the values written to the
+ * DISP_INTF_SEL register, which had to programmed manually. On newer MDP
+ * generations this register is NOP, but we keep the values for historical
+ * reasons.
+ */
 enum dpu_intf_type {
 	INTF_NONE = 0x0,
 	INTF_DSI = 0x1,
 	INTF_HDMI = 0x3,
 	INTF_LCDC = 0x5,
+	/* old eDP found on 8x74 and 8x84 */
 	INTF_EDP = 0x9,
+	/* both DP and eDP,  handled by the new DP driver */
 	INTF_DP = 0xa,
 	INTF_TYPE_MAX,