linux-kernel - Re: [PATCH v2] clk: Add clk_composite_set_rate_and

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20160415221528.GO14441@codeaurora.org>
Date:	Fri, 15 Apr 2016 15:15:28 -0700
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Finlye Xiao <finley.xiao@...k-chips.com>
Cc:	mturquette@...libre.com, heiko@...ech.de,
	linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-rockchip@...ts.infradead.org, zhengxing@...k-chips.com,
	wxt@...k-chips.com, zyw@...k-chips.com, jay.xu@...k-chips.com,
	zhangqing@...k-chips.com, xxx@...k-chips.com,
	huangtao@...k-chips.com
Subject: Re: [PATCH v2] clk: Add clk_composite_set_rate_and_parent

On 04/12, Finlye Xiao wrote:
> From: Finley Xiao <finley.xiao@...k-chips.com>
> 
> When changing the clock-rate, currently a new parent is set first and a
> divider adapted thereafter. This may result in the clock-rate overflowing
> its target rate for a short time if the new parent has a higher rate than
> the old parent.
> 
> While this often doesn't produce negative effects, it can affect components
> in a voltage-scaling environment, like the GPU on the rk3399 socs, where
> the voltage than simply is to low for the temporarily to high clock rate.
> 
> For general clock hirarchies this may need more extensive adaptions to
> the common clock-framework, but at least for composite clocks having
> both parent and rate settings it is easy to create a short-term solution to
> make sure the clock-rate does not overflow the target.
> 
> Signed-off-by: Finley Xiao <finley.xiao@...k-chips.com>
> Reviewed-by: Heiko Stuebner <heiko@...ech.de>
> ---

Applied to clk-next

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project