From: jamie@jamieiles.com (Jamie Iles)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 4/7] clk: Add simple gated clock
Date: Mon, 26 Sep 2011 20:37:33 +0100 [thread overview]
Message-ID: <20110926193733.GC9194@gallagher> (raw)
In-Reply-To: <4E80CE28.9030103@gmail.com>
On Mon, Sep 26, 2011 at 02:10:32PM -0500, Rob Herring wrote:
> On 09/26/2011 01:40 PM, Jamie Iles wrote:
> > On Mon, Sep 26, 2011 at 01:33:08PM -0500, Rob Herring wrote:
> >>> +static void clk_gate_set_bit(struct clk_hw *clk)
> >>> +{
> >>> + struct clk_gate *gate = to_clk_gate(clk);
> >>> + u32 reg;
> >>> +
> >>> + reg = __raw_readl(gate->reg);
> >>> + reg |= BIT(gate->bit_idx);
> >>> + __raw_writel(reg, gate->reg);
> >>
> >> Don't these read-mod-writes need a spinlock around it?
> >>
> >> It's possible to have an enable bits and dividers in the same register.
> >> If you did a set_rate and while doing an enable/disable, there would be
> >> a problem. Also, it may be 2 different clocks in the same register, so
> >> the spinlock needs to be shared and not per clock.
> >
> > Well the prepare lock will be held here and I believe that would be
> > sufficient.
>
> No, the enable spinlock is protecting enable/disable. But set_rate is
> protected by the prepare mutex. So you clearly don't need locking if you
> have a register of only 1 bit enables. If you have a register accessed
> by both enable/disable and prepare/unprepare/set_rate, then you need
> some protection.
OK fair point, but I would guess that if you had a clock like this then
you probably wouldn't use this simple gated clock would you? (speaking
from my world where we have quite simple clocks ;-))
Jamie
next prev parent reply other threads:[~2011-09-26 19:37 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-22 22:26 [PATCH v2 0/7] Add a generic struct clk Mike Turquette
2011-09-22 22:26 ` [PATCH v2 1/7] clk: Add a generic clock infrastructure Mike Turquette
2011-09-25 3:55 ` Grant Likely
2011-09-25 5:26 ` Turquette, Mike
2011-10-03 14:17 ` Rob Herring
2011-10-03 14:25 ` Mark Brown
2011-10-03 15:24 ` Rob Herring
2011-10-03 16:31 ` Mark Brown
2011-10-03 16:43 ` Russell King - ARM Linux
2011-10-03 17:05 ` Mark Brown
2011-10-04 18:09 ` Grant Likely
2011-10-27 11:54 ` Domenico Andreoli
2011-10-03 22:02 ` Rob Herring
2011-10-03 22:15 ` Turquette, Mike
2011-10-06 1:17 ` Saravana Kannan
2011-10-06 16:11 ` Turquette, Mike
2011-10-11 11:25 ` Richard Zhao
2011-10-13 14:44 ` Russell King - ARM Linux
2011-10-13 17:16 ` Turquette, Mike
2011-10-14 8:10 ` Richard Zhao
2011-10-14 10:05 ` Mark Brown
2011-10-14 10:32 ` Richard Zhao
2011-10-16 17:55 ` Sascha Hauer
2011-10-17 8:48 ` Richard Zhao
2011-10-17 9:20 ` Mark Brown
2011-10-17 10:53 ` Richard Zhao
2011-10-17 11:05 ` Sascha Hauer
2011-10-17 11:30 ` Russell King - ARM Linux
2011-10-14 18:14 ` Turquette, Mike
2011-10-15 2:24 ` Richard Zhao
2011-10-15 2:34 ` Richard Zhao
2011-10-16 21:17 ` Turquette, Mike
2011-10-17 11:31 ` Richard Zhao
2011-10-21 9:00 ` Richard Zhao
2011-10-23 12:55 ` Shawn Guo
2011-10-23 16:49 ` Turquette, Mike
2011-09-22 22:26 ` [PATCH v2 2/7] clk: Implement clk_set_rate Mike Turquette
2011-10-11 11:49 ` Richard Zhao
2011-10-23 14:24 ` Shawn Guo
2011-10-23 16:50 ` Turquette, Mike
2011-09-22 22:26 ` [PATCH v2 3/7] clk: Add fixed-rate clock Mike Turquette
2011-10-23 14:30 ` Shawn Guo
2011-10-23 16:51 ` Turquette, Mike
2011-09-22 22:26 ` [PATCH v2 4/7] clk: Add simple gated clock Mike Turquette
2011-09-25 4:02 ` Grant Likely
2011-09-25 5:27 ` Turquette, Mike
2011-09-26 18:33 ` Rob Herring
2011-09-26 18:40 ` Jamie Iles
2011-09-26 19:10 ` Rob Herring
2011-09-26 19:37 ` Jamie Iles [this message]
2011-09-26 22:37 ` Turquette, Mike
2011-09-26 23:30 ` Rob Herring
2011-10-05 1:41 ` Saravana Kannan
2011-10-12 6:46 ` Richard Zhao
2011-10-12 14:59 ` Turquette, Mike
2011-10-16 18:26 ` Sascha Hauer
2011-10-17 6:42 ` Richard Zhao
2011-10-17 17:46 ` Turquette, Mike
2011-10-13 14:45 ` Russell King - ARM Linux
2011-10-13 17:18 ` Turquette, Mike
2011-09-22 22:27 ` [PATCH v2 5/7] clk: Add Kconfig option to build all generic clk drivers Mike Turquette
2011-09-22 22:27 ` [PATCH v2 6/7] clk: Add initial WM831x clock driver Mike Turquette
2011-09-25 4:08 ` Grant Likely
2011-09-25 5:29 ` Turquette, Mike
2011-09-26 9:38 ` Mark Brown
2011-10-04 18:18 ` Grant Likely
2011-10-04 20:50 ` Mark Brown
2011-10-04 23:22 ` Grant Likely
2011-09-22 22:27 ` [PATCH v2 7/7] x86: Enable generic clk API on x86 Mike Turquette
2011-09-22 23:17 ` [PATCH v2 0/7] Add a generic struct clk Turquette, Mike
2011-09-25 4:10 ` Grant Likely
2011-09-29 18:54 ` Mark Brown
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