From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Mon, 26 Oct 2015 15:06:41 -0700 From: Stephen Boyd To: Joachim Eastwood Cc: mturquette@baylibre.com, linux-clk@vger.kernel.org Subject: Re: [PATCH v3 3/3] clk: lpc18xx-cgu: fix potential system hang when disabling unused clocks Message-ID: <20151026220641.GI19782@codeaurora.org> References: <1445705724-20805-1-git-send-email-manabian@gmail.com> <1445705724-20805-4-git-send-email-manabian@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1445705724-20805-4-git-send-email-manabian@gmail.com> List-ID: On 10/24, Joachim Eastwood wrote: > The clock consumer (CCU) of the CGU must be able to check if a CGU > base clock is really running since access to the CCU registers > requires a running base clock. Access with a disabled base clock will > cause the system to hang. Fix this issue by adding code that check if > the parent clock is running in the is_enabled clk_ops callback. Since > certain clocks can be cascaded this must be added to all clock gates. > > The hang would occur if the boot ROM or boot loader didn't setup and > enable the USB0 clock. Then when the clk framework tried to access > the CCU register it would hang the system. > > Signed-off-by: Joachim Eastwood > --- Applied to clk-next -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project