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From: Sascha Hauer <s.hauer@pengutronix.de>
To: Andrey Smirnov <andrew.smirnov@gmail.com>
Cc: barebox@lists.infradead.org
Subject: Re: [PATCH 2/2] clk: clk-sccg-pll: Drop prepare/unprepare for SCCG_PLL2
Date: Wed, 22 Aug 2018 09:31:42 +0200	[thread overview]
Message-ID: <20180822073142.7qdg427bwklqdt5r@pengutronix.de> (raw)
In-Reply-To: <20180821062853.18301-2-andrew.smirnov@gmail.com>

On Mon, Aug 20, 2018 at 11:28:53PM -0700, Andrey Smirnov wrote:
> A number of PLL pairs (e.g. "sys1_pll1" and "sys1_pll2") share the
> same configuration register, so touching PD bit, as is done for
> SCCG_PLL2 in its prepare/unprepare methods will result in shut down of
> both PLLs. This is very undesireable, since attempting to re-parent a
> clock to "sys1_pll2" might result in complete system shutdown due to
> "sys1_pll1" being shut-down as a part of re-parenting process.

I can imagine that there are problems with the way it is currently
handled, but the scenario you describe shouldn't happen. "sys1_pll1"
will never be shut down because it doesn't have a disable hook:

static const struct clk_ops clk_sccg_pll1_ops = {
        .is_enabled     = clk_pll1_is_prepared,
        .recalc_rate    = clk_pll1_recalc_rate,
        .round_rate     = clk_pll1_round_rate,
        .set_rate       = clk_pll1_set_rate,
};

static const struct clk_ops clk_sccg_pll2_ops = {
        .enable         = clk_pll1_prepare,
        .disable        = clk_pll1_unprepare,
        .recalc_rate    = clk_pll2_recalc_rate,
        .round_rate     = clk_pll2_round_rate,
        .set_rate       = clk_pll2_set_rate,
};

Have I missed something?

Sascha

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  reply	other threads:[~2018-08-22  7:31 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-21  6:28 [PATCH 1/2] clk: clk-sccg-pll: Remove leftover debug output Andrey Smirnov
2018-08-21  6:28 ` [PATCH 2/2] clk: clk-sccg-pll: Drop prepare/unprepare for SCCG_PLL2 Andrey Smirnov
2018-08-22  7:31   ` Sascha Hauer [this message]
2018-08-23  1:07     ` Andrey Smirnov
2018-08-23  6:54       ` Sascha Hauer
2018-08-28 19:25         ` Andrey Smirnov
2018-08-22  7:32 ` [PATCH 1/2] clk: clk-sccg-pll: Remove leftover debug output Sascha Hauer

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