linux-kernel - [PATCH] soundwire: cadence: do not extend reset delay

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Date:   Wed, 18 Aug 2021 11:01:30 +0800
From:   Bard Liao <yung-chuan.liao@...ux.intel.com>
To:     alsa-devel@...a-project.org, vkoul@...nel.org
Cc:     vinod.koul@...aro.org, linux-kernel@...r.kernel.org,
        gregkh@...uxfoundation.org, srinivas.kandagatla@...aro.org,
        pierre-louis.bossart@...ux.intel.com, sanyog.r.kale@...el.com,
        bard.liao@...el.com
Subject: [PATCH] soundwire: cadence: do not extend reset delay

From: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>

The duration of the hw_reset is defined as 4096 cycles. The Cadence IP
allows for an additional delay which doesn't seem necessary in
practice: the actual reset sequence duration is defined by the sync_go
mechanism, not by the IP itself.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
Reviewed-by: Rander Wang <rander.wang@...el.com>
Signed-off-by: Bard Liao <yung-chuan.liao@...ux.intel.com>
---
 drivers/soundwire/cadence_master.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
index 0b7f037e6cd0..4fcc3ba93004 100644
--- a/drivers/soundwire/cadence_master.c
+++ b/drivers/soundwire/cadence_master.c
@@ -1032,10 +1032,7 @@ EXPORT_SYMBOL(sdw_cdns_check_self_clearing_bits);
  */
 int sdw_cdns_exit_reset(struct sdw_cdns *cdns)
 {
-	/* program maximum length reset to be safe */
-	cdns_updatel(cdns, CDNS_MCP_CONTROL,
-		     CDNS_MCP_CONTROL_RST_DELAY,
-		     CDNS_MCP_CONTROL_RST_DELAY);
+	/* keep reset delay unchanged to 4096 cycles */
 
 	/* use hardware generated reset */
 	cdns_updatel(cdns, CDNS_MCP_CONTROL,
-- 
2.17.1