Re: [PATCH v7] clk: add si5351 i2c common clock driver

From: Sebastian Hesselbarth
Date: Thu Apr 11 2013 - 04:22:57 EST


On Thu, Apr 11, 2013 at 9:44 AM, Michal Bachraty
<michal.bachraty@xxxxxxxxxxxxxxxxxxx> wrote:
> On Wednesday, April 10, 2013 19:27:25 Sebastian Hesselbarth wrote:
>> Hmm, is there any driver using the clock output? Does it
>> clk_prepare_enable() the clock? I tend not to mess with anything the
>> bootloader or eeprom config left disabled. It works for me, but here the
>> driver will prepare/enable the clock prior use.
>
> For my case, disabled clock outputs in bootloader are correct. I'm working on
> module board with lot of purposes. For one I need to tune frequncy, for other
> not. In some cases I can use clk_prepare_enable. For now, I need to tune clk,
> so I can't use clk_prepare_enable. Si5351 chip has no problem with enabling
> clock output multiple times, when calling clk_set_rate. So if this feature
> will not be in driver, I need to stay with patch upon driver.

Michal,

after thinking about it, I will re-add the power-on on rate change.
Not because I
want to have a workaround for not using clk_prepare_enable() before
clk_set_rate(),
but clkout will remain disabled if you set clock-frequency by DT.
There will be no
superfluous writes to i2c resisters anyway, because clk-si5351 is
using regmap-i2c
that takes care of caching.

Sebastian
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/