Re: [PATCH v4] clk: allow reentrant calls into the clk framework

[Viresh Kumar]

On 27 March 2013 15:10, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
> On Wed, 27 Mar 2013, Mike Turquette wrote:
>
>> Reentrancy into the clock framework from the clk.h api is necessary
>> for clocks that are prepared and unprepared via i2c_transfer (which
>> includes many PMICs and discrete audio chips) as well as for several
>> other use cases.
>
> That explanation sucks.
>
> Why does an i2c clock need reentrancy? Just because it's i2c or what?

I am noway connected to this development but was just going through
your mail and i think i might know the answer why is this required.

Consider an example where an external chip has clock controller and has
bits which can be programmed to enable/disable clock. And this chip is
connected via spi/i2c to SoC.

clk_prepare(peripheral on external chip)
  -> i2c_xfer(to write to external chips register)
      -> clk_enable(i2c controller)
          ->controller-xfer-routine.. and finally we enable clk here...


Sorry if i am on the wrong side :)

--
viresh
--
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/