Re: [PATCH] clk: respect the clock dependencies in of_clk_init
From: Emilio LÃpez
Date: Fri Feb 07 2014 - 11:18:39 EST
Hi Gregory,
El 07/02/14 12:12, Gregory CLEMENT escribiÃ:
On 07/02/2014 16:00, Emilio LÃpez wrote:
El 07/02/14 11:49, Gregory CLEMENT escribiÃ:
On 07/02/2014 15:43, Ezequiel Garcia wrote:
On Fri, Feb 07, 2014 at 09:24:30AM -0500, Jason Cooper wrote:
On Fri, Feb 07, 2014 at 10:06:08AM -0300, Emilio LÃpez wrote:
[snip a great explanation]
Guys, can I get some Tested-by's on this?
In case someone missed Emilio's comment about it, I gave his oneliner
a test on A370 Reference Design. It worked just as well as Sebastian's.
Well ok it's working but this patch is not better than Sebastian, it is
even worth. I don't think it is a good idea at all to totally ignore the
information given by the device tree.
With a bit more work, you can replace the clk_get magic with a call to
of_clk_get_parent_name() or similar to be able to keep overriding stuff
from DT. This way it would completely match the behaviour on
mvebu_coreclk_setup (default to "tclk", allow overriding with DT).
I think you didn't have a look on our implementation:
I did, several times in fact.
the name of the clock
are created by the driver during the initialization.
The name of the clock is always "tclk", as hardcoded on the driver,
unless overridden via clock-output-names from DT (see
mvebu_coreclk_setup). Currently none of your DT that I can see does
this, so in practice it's always "tclk".
That's why we need that
the parent clock are initialized before the gating clock.
You don't really *need* that. The driver just does that because it may
have been convenient at the time and it worked. Defaulting to "tclk" on
mvebu_clk_gating_setup and overriding it if it turns out it has some
other name on the DT (just like on mvebu_coreclk_setup!) should work as
well, and doesn't require complex, bloaty, dependency management.
Rough, untested patch below, so you get the idea.
Cheers,
Emilio
---
drivers/clk/mvebu/common.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/drivers/clk/mvebu/common.c b/drivers/clk/mvebu/common.c
index 25ceccf..730625b 100644
--- a/drivers/clk/mvebu/common.c
+++ b/drivers/clk/mvebu/common.c
@@ -119,19 +119,20 @@ void __init mvebu_clk_gating_setup(struct
device_node *np,
const struct clk_gating_soc_desc *desc)
{
struct clk_gating_ctrl *ctrl;
- struct clk *clk;
void __iomem *base;
- const char *default_parent = NULL;
+ struct of_phandle_args clkspec;
+ const char *default_parent = "tclk";
int n;
base = of_iomap(np, 0);
if (WARN_ON(!base))
return;
- clk = of_clk_get(np, 0);
- if (!IS_ERR(clk)) {
- default_parent = __clk_get_name(clk);
- clk_put(clk);
+ if (!of_parse_phandle_with_args(np, "clocks", "#clock-cells", 0,
&clkspec)) {
+ of_property_read_string_index(clkspec.np, "clock-output-names",
+ clkspec.args_count ? clkspec.args[0] : 0,
+ &default_parent);
+ of_node_put(clkspec.np);
}
ctrl = kzalloc(sizeof(*ctrl), GFP_KERNEL);
--
1.8.5.3
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