Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758922AbaDJTW0 (ORCPT ); Thu, 10 Apr 2014 15:22:26 -0400 Received: from mail-ie0-f170.google.com ([209.85.223.170]:39820 "EHLO mail-ie0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753327AbaDJTWY (ORCPT ); Thu, 10 Apr 2014 15:22:24 -0400 From: Matt Porter To: Lubomir Rintel Cc: Arnd Bergmann , Herbert Xu , Matt Mackall , Paul Gortmaker , Greg Kroah-Hartman , Linux Kernel Mailing List Subject: [PATCH] hwrng: bcm2835: fix oops when rng h/w is accessed during registration Date: Thu, 10 Apr 2014 15:22:10 -0400 Message-Id: <1397157730-31161-1-git-send-email-mporter@linaro.org> X-Mailer: git-send-email 1.8.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit "d9e7972 hwrng: add randomness to system from rng sources" exposed a bug in the bcm2835-rng driver resulting in boot failure on Raspberry Pi due to the following oops: [ 28.261523] BUG: soft lockup - CPU#0 stuck for 23s! [swapper:1] [ 28.271058] [ 28.275958] CPU: 0 PID: 1 Comm: swapper Not tainted 3.14.0+ #11 [ 28.285374] task: db480000 ti: db484000 task.ti: db484000 [ 28.294279] PC is at bcm2835_rng_read+0x28/0x48 [ 28.302276] LR is at hwrng_register+0x1a8/0x238 . . . The RNG h/w is not completely initialized and enabled before hwrng_register() is called and so the bcm2835_rng_read() fails. Fix this by making the warmup/enable writes before registering the RNG source with the hwrng core. Signed-off-by: Matt Porter --- drivers/char/hw_random/bcm2835-rng.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/char/hw_random/bcm2835-rng.c b/drivers/char/hw_random/bcm2835-rng.c index 8c3b255..e900961 100644 --- a/drivers/char/hw_random/bcm2835-rng.c +++ b/drivers/char/hw_random/bcm2835-rng.c @@ -61,18 +61,18 @@ static int bcm2835_rng_probe(struct platform_device *pdev) } bcm2835_rng_ops.priv = (unsigned long)rng_base; + /* set warm-up count & enable */ + __raw_writel(RNG_WARMUP_COUNT, rng_base + RNG_STATUS); + __raw_writel(RNG_RBGEN, rng_base + RNG_CTRL); + /* register driver */ err = hwrng_register(&bcm2835_rng_ops); if (err) { dev_err(dev, "hwrng registration failed\n"); iounmap(rng_base); - } else { + } else dev_info(dev, "hwrng registered\n"); - /* set warm-up count & enable */ - __raw_writel(RNG_WARMUP_COUNT, rng_base + RNG_STATUS); - __raw_writel(RNG_RBGEN, rng_base + RNG_CTRL); - } return err; } -- 1.8.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/