linux-kernel - [PATCH] crypto: caam - double the entropy delay interval for retry

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Message-Id: <20250905101148.212722-1-gaurav.jain@nxp.com>
Date: Fri,  5 Sep 2025 15:41:48 +0530
From: Gaurav Jain <gaurav.jain@....com>
To: Horia Geanta <horia.geanta@....com>,
	Pankaj Gupta <pankaj.gupta@....com>,
	Varun Sethi <V.Sethi@....com>,
	Silvano Di Ninno <silvano.dininno@....com>,
	Meenakshi Aggarwal <meenakshi.aggarwal@....com>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	"David S . Miller" <davem@...emloft.net>
Cc: linux-crypto@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Gaurav Jain <gaurav.jain@....com>
Subject: [PATCH] crypto: caam - double the entropy delay interval for retry

during entropy evaluation, if the generated samples fail
any statistical test, then, all of the bits will be discarded,
and a second set of samples will be generated and tested.

the entropy delay interval should be doubled before performing the
retry.

also, ctrlpriv->rng4_sh_init and inst_handles both reads RNG DRNG
status register, but only inst_handles is updated before every retry.
so only check inst_handles and removing ctrlpriv->rng4_sh_init

Signed-off-by: Gaurav Jain <gaurav.jain@....com>
---
 drivers/crypto/caam/ctrl.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/crypto/caam/ctrl.c b/drivers/crypto/caam/ctrl.c
index a93be395c878..18a850cf0f97 100644
--- a/drivers/crypto/caam/ctrl.c
+++ b/drivers/crypto/caam/ctrl.c
@@ -703,12 +703,12 @@ static int caam_ctrl_rng_init(struct device *dev)
 			 */
 			if (needs_entropy_delay_adjustment())
 				ent_delay = 12000;
-			if (!(ctrlpriv->rng4_sh_init || inst_handles)) {
+			if (!inst_handles) {
 				dev_info(dev,
 					 "Entropy delay = %u\n",
 					 ent_delay);
 				kick_trng(dev, ent_delay);
-				ent_delay += 400;
+				ent_delay = ent_delay * 2;
 			}
 			/*
 			 * if instantiate_rng(...) fails, the loop will rerun
-- 
2.25.1