From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Stephen Boyd <sboyd@codeaurora.org>
Cc: Sylwester Nawrocki <s.nawrocki@samsung.com>,
Tomeu Vizoso <tomeu.vizoso@collabora.com>,
Paul Walmsley <paul@pwsan.com>, Tony Lindgren <tony@atomide.com>,
linux-kernel@vger.kernel.org,
Mike Turquette <mturquette@linaro.org>,
linux-omap@vger.kernel.org,
Javier Martinez Canillas <javier.martinez@collabora.co.uk>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v13 3/6] clk: Make clk API return per-user struct clk instances
Date: Fri, 6 Feb 2015 13:39:20 +0000 [thread overview]
Message-ID: <20150206133920.GC8670@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <54D41A60.8040702@codeaurora.org>
On Thu, Feb 05, 2015 at 05:35:28PM -0800, Stephen Boyd wrote:
> On 02/05/15 16:42, Russell King - ARM Linux wrote:
> > On Thu, Feb 05, 2015 at 02:14:01PM -0800, Stephen Boyd wrote:
> >> Actually we can bury the __clk_create_clk() inside
> >> __of_clk_get_from_provider(). We should also move __clk_get() into there
> >> because right now we have a hole where whoever calls
> >> of_clk_get_from_provider() never calls __clk_get() on the clk, leading
> >> to possible badness. v2 coming soon.
> > There's some other issues here too...
> >
> > sound/soc/kirkwood/kirkwood-i2s.c:
> >
> > priv->clk = devm_clk_get(&pdev->dev, np ? "internal" : NULL);
> > ...
> > priv->extclk = devm_clk_get(&pdev->dev, "extclk");
> > if (IS_ERR(priv->extclk)) {
> > ...
> > } else {
> > if (priv->extclk == priv->clk) {
> > devm_clk_put(&pdev->dev, priv->extclk);
> > priv->extclk = ERR_PTR(-EINVAL);
> > } else {
> > dev_info(&pdev->dev, "found external clock\n");
> > clk_prepare_enable(priv->extclk);
> > soc_dai = kirkwood_i2s_dai_extclk;
> > }
> >
> > It should be fine provided your "trick" is only done for DT clocks,
> > but not for legacy - with legacy, a NULL in the clkdev tables will
> > match both these requests, hence the need to compare the clk_get()
> > return value to tell whether we get the same clock.
> >
>
> Are we still talking about of_clk_get_from_provider()? Or are we talking
> about comparing struct clk pointers?
Comparing struct clk pointers, and the implications of the patch changing
the clk_get() et.al. to be unique struct clk pointers.
> From what I can tell this code is
> now broken because we made all clk getting functions (there's quite a
> few...) return unique pointers every time they're called. It seems that
> the driver wants to know if extclk and clk are the same so it can do
> something differently in kirkwood_set_rate(). Do we need some sort of
> clk_equal(struct clk *a, struct clk *b) function for drivers like this?
Well, the clocks in question are the SoC internal clock (which is more or
less fixed, but has a programmable divider) and an externally supplied
clock, and the IP has a multiplexer on its input which allows us to select
between those two sources.
If it were possible to bind both to the same clock, it wouldn't be a
useful configuration - nothing would be gained from doing so in terms of
available rates.
What the comparison is there for is to catch the case with legacy lookups
where a clkdev lookup entry with a NULL connection ID results in matching
any connection ID passed to clk_get(). If the patch changes this, then
we will have a regression - and this is something which needs fixing
_before_ we do this "return unique clocks".
--
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.
next prev parent reply other threads:[~2015-02-06 13:39 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-23 11:03 [PATCH v13 0/6] Per-user clock constraints Tomeu Vizoso
2015-01-23 11:03 ` [PATCH v13 1/6] clk: Remove unneeded NULL checks Tomeu Vizoso
2015-01-23 11:03 ` [PATCH v13 2/6] clk: Remove __clk_register Tomeu Vizoso
2015-01-23 11:03 ` [PATCH v13 3/6] clk: Make clk API return per-user struct clk instances Tomeu Vizoso
2015-02-01 21:24 ` Mike Turquette
2015-02-02 17:04 ` Tony Lindgren
2015-02-02 19:32 ` Tero Kristo
2015-02-02 20:44 ` Tony Lindgren
2015-02-02 22:48 ` Mike Turquette
2015-02-02 23:11 ` Tony Lindgren
2015-02-02 22:41 ` Mike Turquette
2015-02-02 22:52 ` Stephen Boyd
2015-02-03 7:03 ` Tomeu Vizoso
2015-02-03 8:46 ` Tero Kristo
2015-02-03 15:22 ` Tony Lindgren
2015-02-02 20:45 ` Stephen Boyd
2015-02-02 21:31 ` Julia Lawall
2015-02-02 22:35 ` Stephen Boyd
2015-02-02 22:50 ` Mike Turquette
2015-02-03 16:04 ` [Cocci] " Quentin Lambert
2015-02-04 23:26 ` Stephen Boyd
2015-02-05 15:45 ` Quentin Lambert
2015-02-05 16:02 ` Quentin Lambert
2015-02-06 1:49 ` Stephen Boyd
2015-02-06 2:15 ` Stephen Boyd
2015-02-06 9:01 ` Quentin Lambert
2015-02-06 9:12 ` Julia Lawall
2015-02-06 17:15 ` Stephen Boyd
2015-02-17 22:01 ` Stephen Boyd
2015-03-12 17:20 ` Sebastian Andrzej Siewior
2015-03-12 19:43 ` Stephen Boyd
2015-03-13 3:29 ` Shawn Guo
2015-03-13 8:20 ` Sebastian Andrzej Siewior
2015-03-13 13:42 ` Shawn Guo
2015-03-13 17:42 ` Stephen Boyd
2015-02-05 19:44 ` Sylwester Nawrocki
2015-02-05 20:06 ` Sylwester Nawrocki
2015-02-05 20:07 ` Stephen Boyd
2015-02-05 22:14 ` Stephen Boyd
2015-02-06 0:42 ` Russell King - ARM Linux
2015-02-06 1:35 ` Stephen Boyd
2015-02-06 13:39 ` Russell King - ARM Linux [this message]
2015-02-06 19:30 ` Stephen Boyd
2015-02-06 19:37 ` Russell King - ARM Linux
2015-02-06 19:41 ` Stephen Boyd
2015-02-19 21:32 ` Mike Turquette
2015-02-24 14:08 ` Russell King - ARM Linux
2015-01-23 11:03 ` [PATCH v13 4/6] clk: Add rate constraints to clocks Tomeu Vizoso
2015-01-29 13:31 ` Geert Uytterhoeven
2015-01-29 19:13 ` Stephen Boyd
2015-01-31 1:31 ` Stephen Boyd
2015-01-31 18:36 ` Tomeu Vizoso
2015-02-01 22:18 ` Mike Turquette
2015-02-02 7:59 ` Geert Uytterhoeven
2015-02-02 16:12 ` Tony Lindgren
2015-02-02 17:46 ` Mike Turquette
2015-02-02 17:49 ` Russell King - ARM Linux
2015-02-02 19:21 ` Tony Lindgren
2015-02-02 20:47 ` Tony Lindgren
2015-01-23 11:03 ` [PATCH v13 5/6] clkdev: Export clk_register_clkdev Tomeu Vizoso
2015-02-03 17:35 ` Andy Shevchenko
2015-02-03 17:43 ` Andy Shevchenko
2015-01-23 11:03 ` [PATCH v13 6/6] clk: Add module for unit tests Tomeu Vizoso
2015-01-27 0:55 ` [PATCH v13 0/6] Per-user clock constraints Stephen Boyd
2015-01-27 6:29 ` Tomeu Vizoso
2015-01-28 6:59 ` Tomeu Vizoso
[not found] ` <20150129022633.22722.78592@quantum>
2015-01-29 6:41 ` Tomeu Vizoso
2015-01-29 14:29 ` Mike Turquette
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