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From: Stephen Boyd <sboyd@kernel.org>
To: "A.s. Dong" <aisheng.dong@nxp.com>,
	"linux-clk@vger.kernel.org" <linux-clk@vger.kernel.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"mturquette@baylibre.com" <mturquette@baylibre.com>,
	"shawnguo@kernel.org" <shawnguo@kernel.org>,
	Anson Huang <anson.huang@nxp.com>, Jacky Bai <ping.bai@nxp.com>,
	dl-linux-imx <linux-imx@nxp.com>,
	"A.s. Dong" <aisheng.dong@nxp.com>,
	Stephen Boyd <sboyd@codeaurora.org>
Subject: Re: [PATCH V6 1/9] clk: imx: add gatable clock divider support
Date: Mon, 03 Dec 2018 11:31:47 -0800	[thread overview]
Message-ID: <154386550758.88331.8573266036365450221@swboyd.mtv.corp.google.com> (raw)
In-Reply-To: <1542200198-3017-2-git-send-email-aisheng.dong@nxp.com>

Quoting A.s. Dong (2018-11-14 05:01:35)
> For dividers with zero indicating clock is disabled, instead of giving a
> warning each time like "clkx: Zero divisor and CLK_DIVIDER_ALLOW_ZERO not
> set" in exist code, we'd like to introduce enable/disable function for it.
> e.g.
> 000b - Clock disabled
> 001b - Divide by 1
> 010b - Divide by 2
> ...
> 
> Set rate when the clk is disabled will cache the rate request and only
> when the clk is enabled will the driver actually program the hardware to
> have the requested divider value. Similarly, when the clk is disabled we'll
> write a 0 there, but when the clk is enabled we'll restore whatever rate
> (divider) was chosen last.
> 
> It does mean that recalc rate will be sort of odd, because when the clk is
> off it will return 0, and when the clk is on it will return the right rate.
> So to make things work, we'll need to return the cached rate in recalc rate
> when the clk is off and read the hardware when the clk is on.
> 
> NOTE for the default off divider, the recalc rate will still return 0 as
> there's still no proper preset rate. Enable such divider will give user
> a reminder error message.
> 
> Cc: Stephen Boyd <sboyd@codeaurora.org>
> Cc: Michael Turquette <mturquette@baylibre.com>
> Cc: Shawn Guo <shawnguo@kernel.org>
> Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
> 
> ---

Applied to clk-next


  reply	other threads:[~2018-12-03 19:31 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-14 13:01 [PATCH V6 0/9] clk: add imx7ulp clk support A.s. Dong
2018-11-14 13:01 ` [PATCH V6 1/9] clk: imx: add gatable clock divider support A.s. Dong
2018-12-03 19:31   ` Stephen Boyd [this message]
2018-11-14 13:01 ` [PATCH V6 2/9] clk: fractional-divider: add CLK_FRAC_DIVIDER_ZERO_BASED flag support A.s. Dong
2018-12-03 19:31   ` Stephen Boyd
2018-11-14 13:01 ` [PATCH V6 3/9] clk: imx: add pllv4 support A.s. Dong
2018-12-03 19:31   ` Stephen Boyd
2018-11-14 13:01 ` [PATCH V6 4/9] clk: imx: add pfdv2 support A.s. Dong
2018-12-03 19:31   ` Stephen Boyd
2018-11-14 13:01 ` [PATCH V6 5/9] clk: imx: add imx7ulp composite clk support A.s. Dong
2018-12-03 19:31   ` Stephen Boyd
2018-11-14 13:01 ` [PATCH V6 6/9] dt-bindings: clock: add imx7ulp clock binding doc A.s. Dong
2018-12-03 19:32   ` Stephen Boyd
2018-11-14 13:02 ` [PATCH V6 7/9] clk: imx: make mux parent strings const A.s. Dong
2018-12-03 19:32   ` Stephen Boyd
2018-11-14 13:02 ` [PATCH V6 8/9] clk: imx: implement new clk_hw based APIs A.s. Dong
2018-12-03 19:32   ` Stephen Boyd
2018-11-14 13:02 ` [PATCH V6 9/9] clk: imx: add imx7ulp clk driver A.s. Dong
2018-12-03 19:32   ` Stephen Boyd
2018-12-03 19:31 ` [PATCH V6 0/9] clk: add imx7ulp clk support Stephen Boyd
2018-12-04  1:29   ` Aisheng DONG
2018-12-05 19:41     ` Stephen Boyd
2018-12-10  8:14       ` Shawn Guo
2018-12-10 19:20         ` Stephen Boyd

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