From f321dea6139ab84d24c53e089febdb96f3f9b163 Mon Sep 17 00:00:00 2001
From: Maxime Ripard <maxime@cerno.tech>
Date: Wed, 16 Jun 2021 16:15:28 +0200
Subject: drm/dp_helper: Mention the concurrency requirement hw_mutex
Git-commit: c48935ab6b1280a80b38405369e88470f49809f4
Patch-mainline: v5.15-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225
Drivers that allow concurrent access over multiple DP channels need to
provide additional locking, even though the hw_mutex field might
indicate otherwise. Clarify it in the documentation.
Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210616141529.630719-2-maxime@cerno.tech
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
include/drm/drm_dp_helper.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index d4be8869a617..c33399c34a57 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -1930,6 +1930,10 @@ struct drm_dp_aux {
/**
* @hw_mutex: internal mutex used for locking transfers.
+ *
+ * Note that if the underlying hardware is shared among multiple
+ * channels, the driver needs to do additional locking to
+ * prevent concurrent access.
*/
struct mutex hw_mutex;
--
2.38.1