From: Lubomir Rintel <lkundrak@v3.sk>
To: Stephen Boyd <sboyd@kernel.org>,
Michael Turquette <mturquette@baylibre.com>
Cc: linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH] clk: mmp2: avoid disabling the SP clock when unused
Date: Wed, 16 Jan 2019 18:26:31 +0100 [thread overview]
Message-ID: <73b20a5caef100d5768679cc395168976e86ed04.camel@v3.sk> (raw)
In-Reply-To: <154765664632.169631.9344557684702266461@swboyd.mtv.corp.google.com>
On Wed, 2019-01-16 at 08:37 -0800, Stephen Boyd wrote:
> Quoting Lubomir Rintel (2019-01-16 01:35:05)
> > There could be vital functionality running on the SP PJ1 core it can not be
> > restarted just by turning the clock back on.
> >
> > On the OLPC laptop, the keyboard controller code runs there. It
> > wouldn't be possible to load the driver for it as a module if the clock
> > is disabled on boot.
> >
> > Cc: stable@vger.kernel.org # v4.18+
> > Fixes: commit fc27c2394d96 ("clk: mmp2: add SP clock")
> > Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
> > ---
> > drivers/clk/mmp/clk-of-mmp2.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/clk/mmp/clk-of-mmp2.c b/drivers/clk/mmp/clk-of-mmp2.c
> > index f2a1c9bbaa63..3e33f1295f59 100644
> > --- a/drivers/clk/mmp/clk-of-mmp2.c
> > +++ b/drivers/clk/mmp/clk-of-mmp2.c
> > @@ -246,7 +246,7 @@ static struct mmp_param_gate_clk apmu_gate_clks[] = {
> > {MMP2_CLK_CCIC1, "ccic1_clk", "ccic1_mix_clk", CLK_SET_RATE_PARENT, APMU_CCIC1, 0x1b, 0x1b, 0x0, 0, &ccic1_lock},
> > {MMP2_CLK_CCIC1_PHY, "ccic1_phy_clk", "ccic1_mix_clk", CLK_SET_RATE_PARENT, APMU_CCIC1, 0x24, 0x24, 0x0, 0, &ccic1_lock},
> > {MMP2_CLK_CCIC1_SPHY, "ccic1_sphy_clk", "ccic1_sphy_div", CLK_SET_RATE_PARENT, APMU_CCIC1, 0x300, 0x300, 0x0, 0, &ccic1_lock},
> > - {MMP2_CLK_SP, "sp_clk", NULL, CLK_SET_RATE_PARENT, APMU_SP, 0x1b, 0x1b, 0x0, 0, &sp_lock},
> > + {MMP2_CLK_SP, "sp_clk", NULL, CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, APMU_SP, 0x1b, 0x1b, 0x0, 0, &sp_lock},
>
> Is it a critical clk that should never be turned off?
I don't think it is. It is entirely plausible to have no use for the
"security processor", and in that case it's just okay to keep the clock
disabled.
> If so, mark it as
> CLK_IS_CRITICAL. Either way, please add a comment in the code about why
> CLK_IGNORE_UNUSED or CLK_IS_CRITICAL is used.
Okay.
Thanks,
Lubo
next prev parent reply other threads:[~2019-01-16 17:26 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-16 9:35 [PATCH] clk: mmp2: avoid disabling the SP clock when unused Lubomir Rintel
2019-01-16 16:37 ` Stephen Boyd
2019-01-16 17:26 ` Lubomir Rintel [this message]
2019-01-16 23:29 ` Stephen Boyd
2019-01-17 9:47 ` Lubomir Rintel
2019-01-18 17:31 ` Stephen Boyd
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