On 01/05/2015 11:09 PM, Thierry Reding wrote:
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On Thu, Dec 25, 2014 at 10:28:08AM +0800, Vince Hsu wrote:
On 12/24/2014 09:16 PM, Lucas Stach wrote:
Am Dienstag, den 23.12.2014, 18:39 +0800 schrieb Vince Hsu:
The Tegra124 and later Tegra SoCs have a sepatate rail gating register
to enable/disable the clamp. The original function
tegra_powergate_remove_clamping() is not sufficient for the enable
function. So add a new function which is dedicated to the GPU rail
gating. Also don't refer to the powergate ID since the GPU ID makes no
sense here.
Signed-off-by: Vince Hsu <vinceh@xxxxxxxxxx>
To be honest I don't see the point of this patch.
You are bloating the PMC interface by introducing another exported
function that does nothing different than what the current function
already does.
If you need a way to assert the clamp I would have expected you to
introduce a common function to do this for all power partitions.
I thought about adding an tegra_powergate_assert_clamping(), but that
doesn't make sense to all the power partitions except GPU. Note the
difference in TRM. Any suggestion for the common function?
I don't think extending the powergate API is useful at this point. We've
long had an open TODO item to replace this with a generic API. I did
some prototyping a while ago to use generic power domains for this, that
way all the details and dependencies between the partitions could be
properly modeled.
Can you take a look at my staging/powergate branch here:
https://github.com/thierryreding/linux/commits/staging/powergate
and see if you can use that instead? The idea is to completely hide the
details of power partitions from drivers and use runtime PM instead.
You generic power domains work is exactly what we want for powergate
eventually. :) I recall we used your prototyping in somewhere internal
tree. We have to add more to complete it though, e.g. power domain
dependency, mc flush, and clamping register difference like this patch
does.
But I have a question here. Since the GK20A is not powered on/off by the
PMC except the clamping control, and GK20A has its own power rail, do we
really want to hide the power sequence in the generic powergate code? We
still have to control the voltage level in the GK20A driver through the
regulator framework. It seems weird to me if we put the
regulator_{enable|disable} somewhere other than the GK20A driver.
Thanks,
Vince
Also adding Peter whom I had discussed this with earlier. Can we finally
get this converted? I'd rather not keep complicating this custom API to
avoid making the conversion even more difficult.
Thierry
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