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From: Jerome Brunet <jbrunet@baylibre.com>
To: Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
	linux-amlogic@lists.infradead.org, linux-clk@vger.kernel.org,
	narmstrong@baylibre.com
Cc: linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, mturquette@baylibre.com,
	sboyd@kernel.org
Subject: Re: [RFC v1 5/7] clk: meson: meson8b: mark the CPU clock as CLK_IS_CRITICAL
Date: Thu, 15 Nov 2018 10:46:46 +0100	[thread overview]
Message-ID: <533bd2bd4dced1610a803e7b2d51995e5577ba1d.camel@baylibre.com> (raw)
In-Reply-To: <20181114225725.2821-6-martin.blumenstingl@googlemail.com>

On Wed, 2018-11-14 at 23:57 +0100, Martin Blumenstingl wrote:
> We don't want the common clock framework to disable the "cpu_clk" if
> it's not used by any device. The cpufreq-dt driver does not enable the
> CPU clocks. However, even if it would we would still want the CPU clock
> to be enabled at all times because the CPU clock is also required even
> if we disable CPU frequency scaling on a specific board.
> 
> The reason why we want the CPU clock to be enabled is a clock further up
> in the tree:
> Since commit 6f888e7bc7bd58 ("clk: meson: clk-pll: add enable bit") the
> sys_pll can be disabled. However, since the CPU clock is derived from
> sys_pll we don't want sys_pll to get disabled. The common clock
> framework takes care of that for us by enabling all parent clocks of our
> CPU clock when we mark the CPU clock with CLK_IS_CRITICAL.
> 
> Until now this is not a problem yet because all clocks in the CPU
> clock's tree (including sys_pll) are read-only. However, once we allow
> modifications to the clocks in that tree we will need this.
> 
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
> ---
>  drivers/clk/meson/meson8b.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/meson/meson8b.c b/drivers/clk/meson/meson8b.c
> index 8a3c346e110d..d566dd5bc567 100644
> --- a/drivers/clk/meson/meson8b.c
> +++ b/drivers/clk/meson/meson8b.c
> @@ -646,7 +646,8 @@ static struct clk_regmap meson8b_cpu_clk = {
>  						  "cpu_scale_out_sel" },
>  		.num_parents = 2,
>  		.flags = (CLK_SET_RATE_PARENT |
> -			  CLK_SET_RATE_NO_REPARENT),
> +			  CLK_SET_RATE_NO_REPARENT |
> +			  CLK_IS_CRITICAL),
>  	},
>  };
>  

Acked-by: Jerome Brunet <jbrunet@baylibre.com>


  reply	other threads:[~2018-11-15  9:46 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-14 22:57 [RFC v1 0/7] Meson8b: make the CPU clock mutable Martin Blumenstingl
2018-11-14 22:57 ` [RFC v1 1/7] clk: meson: meson8b: run from the XTAL when changing the CPU frequency Martin Blumenstingl
2018-11-15  9:53   ` Jerome Brunet
2018-11-14 22:57 ` [RFC v1 2/7] clk: meson: meson8b: do not use cpu_div3 for cpu_scale_out_sel Martin Blumenstingl
2018-11-15  9:42   ` Jerome Brunet
2018-11-14 22:57 ` [RFC v1 3/7] clk: meson: clk-pll: check if the clock is already enabled Martin Blumenstingl
2018-11-15  9:14   ` Jerome Brunet
2018-11-14 22:57 ` [RFC v1 4/7] clk: meson: clk-pll: add the is_enabled function in the clk_ops Martin Blumenstingl
2018-11-15  9:16   ` Jerome Brunet
2018-11-14 22:57 ` [RFC v1 5/7] clk: meson: meson8b: mark the CPU clock as CLK_IS_CRITICAL Martin Blumenstingl
2018-11-15  9:46   ` Jerome Brunet [this message]
2018-11-14 22:57 ` [RFC v1 6/7] clk: meson: meson8b: add support for more M/N values in sys_pll Martin Blumenstingl
2018-11-15  9:41   ` Jerome Brunet
2018-11-14 22:57 ` [RFC v1 7/7] clk: meson: meson8b: allow changing the CPU clock tree Martin Blumenstingl
2018-11-15  9:46   ` Jerome Brunet
2018-11-15 10:08 ` [RFC v1 0/7] Meson8b: make the CPU clock mutable Neil Armstrong

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