From: Thomas Petazzoni Subject: [PATCH 1/4] hwrng: omap - write registers after enabling the clock Date: Tue, 7 Mar 2017 15:14:46 +0100 Message-ID: <1488896089-17586-2-git-send-email-thomas.petazzoni@free-electrons.com> References: <1488896089-17586-1-git-send-email-thomas.petazzoni@free-electrons.com> Cc: linux-crypto@vger.kernel.org, romain.perier@collabora.com, Jason Cooper , Andrew Lunn , Sebastian Hesselbarth , Gregory Clement , Nadav Haklai , Hanna Hawa , Yehuda Yitschak , Thomas Petazzoni , stable@vger.kernel.org To: Deepak Saxena , Matt Mackall , Herbert Xu Return-path: Received: from mail.free-electrons.com ([62.4.15.54]:58562 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751270AbdCGORa (ORCPT ); Tue, 7 Mar 2017 09:17:30 -0500 In-Reply-To: <1488896089-17586-1-git-send-email-thomas.petazzoni@free-electrons.com> Sender: linux-crypto-owner@vger.kernel.org List-ID: Commit 383212425c926 ("hwrng: omap - Add device variant for SafeXcel IP-76 found in Armada 8K") added support for the SafeXcel IP-76 variant of the IP. This modification included getting a reference and enabling a clock. Unfortunately, this was done *after* writing to the RNG_INTMASK_REG register. This generally works fine when the driver is built-in because the clock might have been left enabled by the bootloader, but fails short when the driver is built as a module: it causes a system hang because a register is being accessed while the clock is not enabled. This commit fixes that by making the register access *after* enabling the clock. This issue was found by the kernelci.org testing effort. Fixes: 383212425c926 ("hwrng: omap - Add device variant for SafeXcel IP-76 found in Armada 8K") Cc: Signed-off-by: Thomas Petazzoni --- drivers/char/hw_random/omap-rng.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/char/hw_random/omap-rng.c b/drivers/char/hw_random/omap-rng.c index 3ad86fd..efa3747 100644 --- a/drivers/char/hw_random/omap-rng.c +++ b/drivers/char/hw_random/omap-rng.c @@ -397,7 +397,6 @@ static int of_get_omap_rng_device_details(struct omap_rng_dev *priv, irq, err); return err; } - omap_rng_write(priv, RNG_INTMASK_REG, RNG_SHUTDOWN_OFLO_MASK); priv->clk = of_clk_get(pdev->dev.of_node, 0); if (IS_ERR(priv->clk) && PTR_ERR(priv->clk) == -EPROBE_DEFER) @@ -408,6 +407,8 @@ static int of_get_omap_rng_device_details(struct omap_rng_dev *priv, dev_err(&pdev->dev, "unable to enable the clk, " "err = %d\n", err); } + + omap_rng_write(priv, RNG_INTMASK_REG, RNG_SHUTDOWN_OFLO_MASK); } return 0; } -- 2.7.4