From 4da0680f24c9af2de8406ded68c4ef967f448de3 Mon Sep 17 00:00:00 2001
From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Date: Wed, 11 Dec 2019 19:45:06 -0600
Subject: [PATCH] soundwire: intel: add mutex for shared SHIM register access
Git-commit: 4da0680f24c9af2de8406ded68c4ef967f448de3
Patch-mainline: v5.6-rc1
References: jsc#SLE-16518

Some of the Intel SoundWire SHIM registers contain fields for

Acked-by: Takashi Iwai <tiwai@suse.de>

different links. Without protection, the master drivers for the
different links will access these shared registers, leading to invalid
configurations and timeouts (specifically when changing CPA/SPA
power-related registers and polling for the changes to be applied).

A mutex is added to make sure all rmw access to those registers are
serialized.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20191212014507.28050-11-pierre-louis.bossart@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
---
 include/linux/soundwire/sdw_intel.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/soundwire/sdw_intel.h b/include/linux/soundwire/sdw_intel.h
index 073121c49695..45fa6d93197f 100644
--- a/include/linux/soundwire/sdw_intel.h
+++ b/include/linux/soundwire/sdw_intel.h
@@ -71,6 +71,7 @@ struct sdw_intel_link_res;
  * @links: information for each link (controller-specific and kept
  * opaque here)
  * @link_list: list to handle interrupts across all links
+ * @shim_lock: mutex to handle concurrent rmw access to shared SHIM registers.
  */
 struct sdw_intel_ctx {
 	int count;
@@ -79,6 +80,7 @@ struct sdw_intel_ctx {
 	acpi_handle handle;
 	struct sdw_intel_link_res *links;
 	struct list_head link_list;
+	struct mutex shim_lock; /* lock for access to shared SHIM registers */
 };
 
 /**
-- 
2.16.4