linux-kernel - Re: [PATCH v2 2/4] clk: rockchip: rk3228: make noc and some special clk as critical

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Date:   Thu, 30 Mar 2017 15:10:24 +0200
From:   Heiko Stuebner <heiko@...ech.de>
To:     Maxime Ripard <maxime.ripard@...e-electrons.com>
Cc:     Elaine Zhang <zhangqing@...k-chips.com>, xf@...k-chips.com,
        huangtao@...k-chips.com, mturquette@...libre.com,
        sboyd@...eaurora.org, linux-kernel@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-rockchip@...ts.infradead.org,
        xxx@...k-chips.com, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 2/4] clk: rockchip: rk3228: make noc and some special clk as critical_clocks

Am Donnerstag, 30. März 2017, 14:44:17 CEST schrieb Maxime Ripard:
> On Tue, Mar 28, 2017 at 06:06:52PM +0800, Elaine Zhang wrote:
> > Signed-off-by: Elaine Zhang <zhangqing@...k-chips.com>
> > ---
> >  drivers/clk/rockchip/clk-rk3228.c | 30 +++++++++++++++++++++++++++++-
> >  1 file changed, 29 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/clk/rockchip/clk-rk3228.c b/drivers/clk/rockchip/clk-rk3228.c
> > index db6e5a9e6de6..4d3203f887e2 100644
> > --- a/drivers/clk/rockchip/clk-rk3228.c
> > +++ b/drivers/clk/rockchip/clk-rk3228.c
> > @@ -445,7 +445,7 @@ enum rk3228_plls {
> >  			RK2928_CLKGATE_CON(2), 12, GFLAGS,
> >  			&rk3228_spdif_fracmux),
> >  
> > -	GATE(0, "jtag", "ext_jtag", 0,
> > +	GATE(0, "jtag", "ext_jtag", CLK_IGNORE_UNUSED,
> 
> CLK_IGNORE_UNUSED only prevents a given clock from being gated at
> late_initcall time, but will not prevent it from being gated later in
> the life of the system, for example if a reparenting occurs, or if all
> the clocks sharing the same clock tree become disabled.
> 
> If your clock really should never ever be gated in order for Linux to
> operate properly, you should use CLK_IS_CRITICAL.

in the scope of the jtag clock, that is actually ok. As it only gates
some clock supplied from an external source (ext_jtag).