From 5d37f1ed8bf4654f48c9e4b76021ee3813d18ac1 Mon Sep 17 00:00:00 2001
From: popcornmix <popcornmix@gmail.com>
Date: Tue, 6 Dec 2016 17:05:39 +0000
Subject: [PATCH] bcm2835-rng: Avoid initialising if already enabled

Avoids the 0x40000 cycles of warmup again if firmware has already used it
---
 drivers/char/hw_random/bcm2835-rng.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/char/hw_random/bcm2835-rng.c
+++ b/drivers/char/hw_random/bcm2835-rng.c
@@ -106,8 +106,10 @@ static int bcm2835_rng_init(struct hwrng
 	}
 
 	/* set warm-up count & enable */
-	rng_writel(priv, RNG_WARMUP_COUNT, RNG_STATUS);
-	rng_writel(priv, RNG_RBGEN, RNG_CTRL);
+	if (!(rng_readl(priv, RNG_CTRL) & RNG_RBGEN)) {
+		rng_writel(priv, RNG_WARMUP_COUNT, RNG_STATUS);
+		rng_writel(priv, RNG_RBGEN, RNG_CTRL);
+	}
 
 	return ret;
 }
