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From: Stephen Boyd <sboyd@codeaurora.org>
To: Finlye Xiao <finley.xiao@rock-chips.com>
Cc: mturquette@baylibre.com, heiko@sntech.de,
	linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-rockchip@lists.infradead.org, zhengxing@rock-chips.com,
	wxt@rock-chips.com, zyw@rock-chips.com, jay.xu@rock-chips.com,
	zhangqing@rock-chips.com, xxx@rock-chips.com,
	huangtao@rock-chips.com
Subject: Re: [PATCH v2] clk: Add clk_composite_set_rate_and_parent
Date: Fri, 15 Apr 2016 15:15:28 -0700	[thread overview]
Message-ID: <20160415221528.GO14441@codeaurora.org> (raw)
In-Reply-To: <1460450619-1118-1-git-send-email-finley.xiao@rock-chips.com>

On 04/12, Finlye Xiao wrote:
> From: Finley Xiao <finley.xiao@rock-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@rock-chips.com>
> Reviewed-by: Heiko Stuebner <heiko@sntech.de>
> ---

Applied to clk-next

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

WARNING: multiple messages have this Message-ID (diff)
From: sboyd@codeaurora.org (Stephen Boyd)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2] clk: Add clk_composite_set_rate_and_parent
Date: Fri, 15 Apr 2016 15:15:28 -0700	[thread overview]
Message-ID: <20160415221528.GO14441@codeaurora.org> (raw)
In-Reply-To: <1460450619-1118-1-git-send-email-finley.xiao@rock-chips.com>

On 04/12, Finlye Xiao wrote:
> From: Finley Xiao <finley.xiao@rock-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@rock-chips.com>
> Reviewed-by: Heiko Stuebner <heiko@sntech.de>
> ---

Applied to clk-next

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

  reply	other threads:[~2016-04-15 22:15 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-04-11  1:54 [PATCH v1] clk: Add clk_composite_set_rate_and_parent Finlye Xiao
2016-04-11  1:54 ` Finlye Xiao
2016-04-11  1:54 ` Finlye Xiao
2016-04-12  5:04 ` Heiko Stuebner
2016-04-12  5:04   ` Heiko Stuebner
2016-04-14  0:43   ` Stephen Boyd
2016-04-14  0:43     ` Stephen Boyd
2016-04-14  4:56     ` Heiko Stübner
2016-04-14  4:56       ` Heiko Stübner
2016-04-12  8:43 ` [PATCH v2] " Finlye Xiao
2016-04-12  8:43   ` Finlye Xiao
2016-04-15 22:15   ` Stephen Boyd [this message]
2016-04-15 22:15     ` Stephen Boyd

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