linux-kernel - Re: [PATCH] clk: Fix CLK_SET_RATE_GATE flag validation in clk_set_rate().

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Date:	Wed, 16 May 2012 08:25:01 +0800
From:	Richard Zhao <richard.zhao@...escale.com>
To:	Saravana Kannan <skannan@...eaurora.org>
CC:	<linux-arm-kernel@...ts.infradead.org>,
	Mike Turquette <mturquette@...aro.org>,
	Paul Walmsley <paul@...an.com>,
	Shawn Guo <shawn.guo@...escale.com>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Rob Herring <rob.herring@...xeda.com>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Russell King <linux@....linux.org.uk>,
	Andrew Lunn <andrew@...n.ch>,
	Stephen Boyd <sboyd@...eaurora.org>,
	Linus Walleij <linus.walleij@...ricsson.com>,
	<linux-arm-msm@...r.kernel.org>,
	Magnus Damm <magnus.damm@...il.com>,
	<linux-kernel@...r.kernel.org>,
	Amit Kucheria <amit.kucheria@...aro.org>,
	Richard Zhao <richard.zhao@...aro.org>,
	Grant Likely <grant.likely@...retlab.ca>,
	Deepak Saxena <dsaxena@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jamie Iles <jamie@...ieiles.com>,
	Arnd Bergman <arnd.bergmann@...aro.org>,
	Jeremy Kerr <jeremy.kerr@...onical.com>
Subject: Re: [PATCH] clk: Fix CLK_SET_RATE_GATE flag validation in
 clk_set_rate().

On Tue, May 15, 2012 at 01:43:42PM -0700, Saravana Kannan wrote:
> The clk_set_rate() code shouldn't check the clock's enable count when
> validating CLK_SET_RATE_GATE flag since the enable count could change after
> the validation. Similar to clk_set_parent(), it should instead check the
> prepare count. The prepare count should go to zero only when the end user
> expects the clock to not be enabled in the future. Since the code already
> grabs the prepare count before validation, it's not possible for prepare
> count to change after validation and by association not possible for a well
> behaving end user to enable the clock while the set rate is in progress.
> 
> Signed-off-by: Saravana Kannan <skannan@...eaurora.org>
Reviewed-by: Richard Zhao <richard.zhao@...escale.com>
> ---
> Please let me know if you don't want me to directly email or CC you in my
> clock related patches. I don't want to spam anyone. Also, let me know if
> you want me add you to my standard list of people to cc in my clock
> patches.
> 
>  drivers/clk/clk.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index 09b9112..f5b9d3c 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -903,7 +903,7 @@ int clk_set_rate(struct clk *clk, unsigned long rate)
>  	if (rate == clk->rate)
>  		goto out;
>  
> -	if ((clk->flags & CLK_SET_RATE_GATE) && __clk_is_enabled(clk)) {
> +	if ((clk->flags & CLK_SET_RATE_GATE) && clk->prepare_count) {
>  		ret = -EBUSY;
>  		goto out;
>  	}
> -- 
> 1.7.8.3
> 
> Sent by an employee of the Qualcomm Innovation Center, Inc.
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 

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