drm/amd/display: Use HW lock mgr for PSR1 when only one eDP

commit acbf16a6ae775b4db86f537448cc466288aa307e upstream.

[WHY]
DMUB locking is important to make sure that registers aren't accessed
while in PSR.  Previously it was enabled but caused a deadlock in
situations with multiple eDP panels.

[HOW]
Detect if multiple eDP panels are in use to decide whether to use
lock. Refactor the function so that the first check is for PSR-SU
and then replay is in use to prevent having to look up number
of eDP panels for those configurations.

Fixes: f245b400a223 ("Revert "drm/amd/display: Use HW lock mgr for PSR1"")
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3965
Reviewed-by: ChiaHsuan Chung <[email protected]>
Signed-off-by: Mario Limonciello <[email protected]>
Signed-off-by: Alex Hung <[email protected]>
Tested-by: Daniel Wheeler <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>
(cherry picked from commit ed569e1279a3045d6b974226c814e071fa0193a6)
Cc: [email protected]
[superm1: Adjust for missing replay support bfeefe6ea5f1,
          Adjust for dc_get_edp_links not being renamed from get_edp_links()]
Signed-off-by: Mario Limonciello <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: superm1

drivers/gpu/drm/amd/display/dc/dce/dmub_hw_lock_mgr.c

@@ -67,5 +67,17 @@ bool should_use_dmub_lock(struct dc_link *link)
 {
 	if (link->psr_settings.psr_version == DC_PSR_VERSION_SU_1)
 		return true;
+
+	/* only use HW lock for PSR1 on single eDP */
+	if (link->psr_settings.psr_version == DC_PSR_VERSION_1) {
+		struct dc_link *edp_links[MAX_NUM_EDP];
+		int edp_num;
+
+		get_edp_links(link->dc, edp_links, &edp_num);
+
+		if (edp_num == 1)
+			return true;
+	}
+
 	return false;
 }