On Mon, Jan 18, 2010 at 10:34:29AM +0900, Thomas Abraham wrote:
> Hi Ben,
>
> On Mon, Jan 18, 2010 at 10:10 AM, Ben Dooks <ben-linux@xxxxxxxxx> wrote:
> > On Mon, Jan 18, 2010 at 09:38:17AM +0900, Thomas Abraham wrote:
> >> The function s3c_set_clksrc should return if the clksrc_clk clock has
> >> only one possible parent clock.
> >
> > Does this actually relate to a real bug or is this something that you've
> > come across whilst reading the code?
>
> This is required in cases where a clock has a divider but no mux. In
> s3c_register_clksrc function, after the default set of clock
> operations are assigned, the parent clock set function s3c_set_clksrc
> is called. For clocks that do not have mux, the call to s3c_set_clksrc
> is incorrect.
If you have a look at s3c_set_clksrc() , you will find it already
checks to see if clk->reg_src.reg is set. It also doesn't call the
setparent directly either, as it only needs to set clk->clk.parent
field before exiting.
132 u32 clksrc = 0;
133
134 if (clk->reg_src.reg)
135 clksrc = __raw_readl(clk->reg_src.reg);
136
137 clksrc &= mask;
138 clksrc >>= clk->reg_src.shift;
139
140 if (clksrc > srcs->nr_sources || !srcs->sources[clksrc]) {
141 printk(KERN_ERR "%s: bad source %d\n",
142 clk->clk.name, clksrc);
143 return;
144 }
145
146 clk->clk.parent = srcs->sources[clksrc];
This allows us to do some basic verification that the clksrc's sources
data is valud (such that srcs->nr_sources at least contains one source
and that it is not NULL).
> >
> > From arch/arm/plat-samnsung/clock-clksrc.c:
> >
> > 181 if (!clksrc->reg_div.reg)
> > 182 clksrc->clk.ops = &clksrc_ops_nodiv;
> > 183 else if (!clksrc->reg_src.reg)
> > 184 clksrc->clk.ops = &clksrc_ops_nosrc;
> > 185 else
> > 186 clksrc->clk.ops = &clksrc_ops;
> >
> > So we change the ops dependant on which register(s) we have availalbe.
> >
> >> Signed-of-by: Thomas Abraham <thomas.ab@xxxxxxxxxxx>
> >> ---
> >> arch/arm/plat-samsung/clock-clksrc.c | 5 +++--
> >> 1 files changed, 3 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/arch/arm/plat-samsung/clock-clksrc.c b/arch/arm/plat-samsung/clock-clksrc.c
> >> index 33c633a..80da4c4 100644
> >> --- a/arch/arm/plat-samsung/clock-clksrc.c
> >> +++ b/arch/arm/plat-samsung/clock-clksrc.c
> >> @@ -131,9 +131,10 @@ void __init_or_cpufreq s3c_set_clksrc(struct clksrc_clk *clk, bool announce)
> >> u32 mask = bit_mask(clk->reg_src.shift, clk->reg_src.size);
> >> u32 clksrc = 0;
> >>
> >> - if (clk->reg_src.reg)
> >> - clksrc = __raw_readl(clk->reg_src.reg);
> >> + if (!clk->reg_src.reg)
> >> + return;
> >>
> >> + clksrc = __raw_readl(clk->reg_src.reg);
> >> clksrc &= mask;
> >> clksrc >>= clk->reg_src.shift;
> >>
> >> --
> >> 1.6.3.3
> >>
> >
> > --
> > --
> > Ben
> >
> > Q: What's a light-year?
> > A: One-third less calories than a regular year.
> >
> > --
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> >
>
>
> Thanks,
> Thomas.
> --
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--
--
Ben
Q: What's a light-year?
A: One-third less calories than a regular year.
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