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From:   Fabio Estevam <festevam@gmail.com>
To:     herbert@gondor.apana.org.au
Cc:     horia.geanta@nxp.com, gaurav.jain@nxp.com, V.Sethi@nxp.com,
        linux-crypto@vger.kernel.org, Fabio Estevam <festevam@denx.de>
Subject: [PATCH v3] crypto: caam - fix i.MX6SX entropy delay value
Date:   Mon, 18 Apr 2022 09:27:28 -0300
Message-Id: <20220418122728.203919-1-festevam@gmail.com>
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From: Fabio Estevam <festevam@denx.de>

Since commit 358ba762d9f1 ("crypto: caam - enable prediction resistance
in HRWNG") the following CAAM errors can be seen on i.MX6SX:

caam_jr 2101000.jr: 20003c5b: CCB: desc idx 60: RNG: Hardware error
hwrng: no data available
caam_jr 2101000.jr: 20003c5b: CCB: desc idx 60: RNG: Hardware error

This error is due to an incorrect entropy delay for i.MX6SX.

Fix it by increasing the minimum entropy delay for i.MX6SX
as done in U-Boot:
https://patchwork.ozlabs.org/project/uboot/patch/20220415111049.2565744-1-gaurav.jain@nxp.com/

Fixes: 358ba762d9f1 ("crypto: caam - enable prediction resistance in HRWNG") 
Signed-off-by: Fabio Estevam <festevam@denx.de>
---
Changes since v2:
- Added Fixes tag. (Horia)

Change since v1:
- Align the fix with U-Boot.

 drivers/crypto/caam/ctrl.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/crypto/caam/ctrl.c b/drivers/crypto/caam/ctrl.c
index ca0361b2dbb0..c515c20442d5 100644
--- a/drivers/crypto/caam/ctrl.c
+++ b/drivers/crypto/caam/ctrl.c
@@ -648,6 +648,8 @@ static int caam_probe(struct platform_device *pdev)
 			return ret;
 	}
 
+	if (of_machine_is_compatible("fsl,imx6sx"))
+		ent_delay = 12000;
 
 	/* Get configuration properties from device tree */
 	/* First, get register page */
@@ -871,6 +873,15 @@ static int caam_probe(struct platform_device *pdev)
 			 */
 			ret = instantiate_rng(dev, inst_handles,
 					      gen_sk);
+			/*
+			 * Entropy delay is calculated via self-test method.
+			 * Self-test is run across different voltages and
+			 * temperatures.
+			 * If worst case value for ent_dly is identified,
+			 * the loop can be skipped for that platform.
+			 */
+			if (of_machine_is_compatible("fsl,imx6sx"))
+				break;
 			if (ret == -EAGAIN)
 				/*
 				 * if here, the loop will rerun,
-- 
2.25.1