From: Mike Turquette <mturquette@linaro.org>
To: Tomeu Vizoso <tomeu.vizoso@collabora.com>,
linux-kernel@vger.kernel.org,
"Stephen Boyd" <sboyd@codeaurora.org>
Cc: "Tomeu Vizoso" <tomeu.vizoso@collabora.com>,
"Paul Walmsley" <paul@pwsan.com>,
"Tony Lindgren" <tony@atomide.com>,
linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
t-kristo@ti.com
Subject: Re: [PATCH v13 3/6] clk: Make clk API return per-user struct clk instances
Date: Sun, 01 Feb 2015 13:24:32 -0800 [thread overview]
Message-ID: <20150201212432.22722.70917@quantum> (raw)
In-Reply-To: <1422011024-32283-4-git-send-email-tomeu.vizoso@collabora.com>
Quoting Tomeu Vizoso (2015-01-23 03:03:30)
> Moves clock state to struct clk_core, but takes care to change as little API as
> possible.
>
> struct clk_hw still has a pointer to a struct clk, which is the
> implementation's per-user clk instance, for backwards compatibility.
>
> The struct clk that clk_get_parent() returns isn't owned by the caller, but by
> the clock implementation, so the former shouldn't call clk_put() on it.
>
> Because some boards in mach-omap2 still register clocks statically, their clock
> registration had to be updated to take into account that the clock information
> is stored in struct clk_core now.
Tero, Paul & Tony,
Tomeu's patch unveils a problem with omap3_noncore_dpll_enable and
struct dpll_data, namely this snippet from
arch/arm/mach-omap2/dpll3xxx.c:
parent = __clk_get_parent(hw->clk);
if (__clk_get_rate(hw->clk) == __clk_get_rate(dd->clk_bypass)) {
WARN(parent != dd->clk_bypass,
"here0, parent name is %s, bypass name is %s\n",
__clk_get_name(parent), __clk_get_name(dd->clk_bypass));
r = _omap3_noncore_dpll_bypass(clk);
} else {
WARN(parent != dd->clk_ref,
"here1, parent name is %s, ref name is %s\n",
__clk_get_name(parent), __clk_get_name(dd->clk_ref));
r = _omap3_noncore_dpll_lock(clk);
}
struct dpll_data has members clk_ref and clk_bypass which are struct clk
pointers. This was always a bit of a violation of the clk.h contract
since drivers are not supposed to deref struct clk pointers. Now that we
generate unique pointers for each call to clk_get (clk_ref & clk_bypass
are populated by of_clk_get in ti_clk_register_dpll) then the pointer
comparisons above will never be equal (even if they resolve down to the
same struct clk_core). I added the verbose traces to the WARNs above to
illustrate the point: the names are always the same but the pointers
differ.
AFAICT this doesn't break anything, but booting on OMAP3+ results in
noisy WARNs.
I think the correct fix is to replace clk_bypass and clk_ref pointers
with a simple integer parent_index. In fact we already have this index.
See how the pointers are populated in ti_clk_register_dpll:
dd->clk_ref = of_clk_get(node, 0);
dd->clk_bypass = of_clk_get(node, 1);
Tony, the same problem affects the FAPLL code which copy/pastes some of
the DPLL code.
Thoughts?
Regards,
Mike
next prev parent reply other threads:[~2015-02-01 21:24 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 [this message]
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
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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