linux-kernel - Re: [PATCH] clk: Fix __GFP_FS allocation with irqs disabled

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Message-ID: <20150117220532.22722.48317@quantum>
Date:	Sat, 17 Jan 2015 14:05:32 -0800
From:	Mike Turquette <mturquette@...aro.org>
To:	Stephen Boyd <sboyd@...eaurora.org>,
	"Krzysztof Kozlowski" <k.kozlowski@...sung.com>,
	linux-kernel@...r.kernel.org
Cc:	"Rajendra Nayak" <rnayak@...com>,
	"Kyungmin Park" <kyungmin.park@...sung.com>,
	"Marek Szyprowski" <m.szyprowski@...sung.com>,
	"Bartlomiej Zolnierkiewicz" <b.zolnierkie@...sung.com>,
	stable@...r.kernel.org
Subject: Re: [PATCH] clk: Fix __GFP_FS allocation with irqs disabled

Quoting Stephen Boyd (2014-12-22 11:26:42)
> On 12/22/2014 10:38 AM, Stephen Boyd wrote:
> > On 12/22/2014 03:45 AM, Krzysztof Kozlowski wrote:
> >
> >> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> >> index f4963b7d4e17..35079302a650 100644
> >> --- a/drivers/clk/clk.c
> >> +++ b/drivers/clk/clk.c
> >> @@ -1150,6 +1150,12 @@ static int clk_fetch_parent_index(struct clk *clk, struct clk *parent)
> >>  {
> >>      int i;
> >>  
> >> +    if (clk->num_parents == 1) {
> >> +            if (IS_ERR_OR_NULL(clk->parent))
> >> +                    clk->parent = __clk_lookup(clk->parent_names[0]);
> >> +            return 0;
> >> +    }
> >> +
> >>      if (!clk->parents) {
> >>              clk->parents = kcalloc(clk->num_parents,
> >>                                      sizeof(struct clk *), GFP_KERNEL);
> > This may be a worthwhile optimization, but I wonder why the clk_ops for
> > this clock need to fetch the parent index at all? Which clock are we
> > actually dealing with here?
> >
> 
> The clk_set_rate() call should still be fixed, but we can probably do
> this too.
> 
> ---8<---
> 
> From: Stephen Boyd <sboyd@...eaurora.org>
> Date: Mon, 22 Dec 2014 11:24:28 -0800
> Subject: [PATCH] clk: Skip fetching index for single parent clocks
> 
> We don't need to fetch the parent index for clocks if they only
> have one parent. Doing this also avoid an unnecessary allocation
> for the parent cache.
> 
> Signed-off-by: Stephen Boyd <sboyd@...eaurora.org>
> ---
>  drivers/clk/clk.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index 675f37a7329f..e3a2d36124fd 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -1420,7 +1420,7 @@ static struct clk *clk_calc_new_rates(struct clk *clk, unsigned long rate)
>         }
>  
>         /* try finding the new parent index */
> -       if (parent) {
> +       if (parent && clk->num_parents > 1) {
>                 p_index = clk_fetch_parent_index(clk, parent);
>                 if (p_index < 0) {
>                         pr_debug("%s: clk %s can not be parent of clk %s\n",

Applied to clk-next.

Regards,
Mike

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