linux-kernel - [PATCH v3 1/2] crypto: ccp - reduce tee command status polling interval from 5ms to 1ms

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Date:   Mon, 15 Mar 2021 13:55:28 +0530
From:   Rijo Thomas <Rijo-john.Thomas@....com>
To:     Tom Lendacky <thomas.lendacky@....com>,
        John Allen <john.allen@....com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S . Miller" <davem@...emloft.net>,
        linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org
Cc:     Rijo Thomas <Rijo-john.Thomas@....com>,
        Mythri Pandeshwara krishna <mythri.pandeshwarakrishna@....com>,
        Devaraj Rangasamy <Devaraj.Rangasamy@....com>,
        Jens Wiklander <jens.wiklander@...aro.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>
Subject: [PATCH v3 1/2] crypto: ccp - reduce tee command status polling interval from 5ms to 1ms

The PSP TEE device driver polls the command status variable every
5ms to check for command completion. Reduce this time to 1ms so that
there is an improvement in driver response time to clients which submit
TEE commands.

Reviewed-by: Devaraj Rangasamy <Devaraj.Rangasamy@....com>
Signed-off-by: Rijo Thomas <Rijo-john.Thomas@....com>
---
 drivers/crypto/ccp/tee-dev.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/crypto/ccp/tee-dev.c b/drivers/crypto/ccp/tee-dev.c
index 5e697a90ea7f..910b71df2aef 100644
--- a/drivers/crypto/ccp/tee-dev.c
+++ b/drivers/crypto/ccp/tee-dev.c
@@ -5,7 +5,7 @@
  * Author: Rijo Thomas <Rijo-john.Thomas@....com>
  * Author: Devaraj Rangasamy <Devaraj.Rangasamy@....com>
  *
- * Copyright 2019 Advanced Micro Devices, Inc.
+ * Copyright (C) 2019,2021 Advanced Micro Devices, Inc.
  */
 
 #include <linux/types.h>
@@ -309,14 +309,14 @@ static int tee_wait_cmd_completion(struct psp_tee_device *tee,
 				   struct tee_ring_cmd *resp,
 				   unsigned int timeout)
 {
-	/* ~5ms sleep per loop => nloop = timeout * 200 */
-	int nloop = timeout * 200;
+	/* ~1ms sleep per loop => nloop = timeout * 1000 */
+	int nloop = timeout * 1000;
 
 	while (--nloop) {
 		if (resp->cmd_state == TEE_CMD_STATE_COMPLETED)
 			return 0;
 
-		usleep_range(5000, 5100);
+		usleep_range(1000, 1100);
 	}
 
 	dev_err(tee->dev, "tee: command 0x%x timed out, disabling PSP\n",
-- 
2.17.1