Quoting David Dai (2018-12-04 17:14:10)
On 12/4/2018 2:34 PM, Stephen Boyd wrote:How is this different from bus bandwidth requests? In those cases the
Quoting Alex Elder (2018-12-04 13:41:47)The clock rate is translated into a unitless threshold value sent as
On 12/4/18 1:24 PM, Stephen Boyd wrote:But then we translate that clock rate into a bandwidth request to the
Quoting David Dai (2018-12-03 19:50:13)The IPA core clock is a *clock*, not a bus. Representing it as if
Add IPA clock support by extending the current clk rpmh driver to supportYes, but why? Does the IPA driver need to set clk rates and that somehow
clocks that are managed by a different type of RPMh resource known as
Bus Clock Manager(BCM).
doesn't work as a bandwidth request?
it were a bus, abusing the interconnect interface--pretending a bandwidth
request is really a clock rate request--is kind of kludgy. I think Bjorn
and David (and maybe Georgi? I don't know) decided a long time ago that
exposing this as a clock is the right way to do it. I agree with that.
BCM hardware? Seems really weird because it's doing the opposite of what
you say is abusive. What does the IPA driver plan to do with this clk?
Calculate a frequency by knowing that it really boils down to some
bandwidth that then gets converted back into some clock frequency? Do we
have the user somewhere that can be pointed to?
part of the rpmh msg
that BCM takes to select a performance. In this case, the unit
conversion is based on
the unit value read from the aux data which is in Khz. I understand that
this wasn't
explicitly mentioned anywhere and I'll improve on that next patch.
bandwidth is calculated in bits per second or something like that, and
written to the hardware so it can convert that bandwidth into kHz and
set a bus clk frequency in the clock controller? So in the IPA case
we've skipped the bps to kHz conversion step and gone straight to the
clk frequency setting part? Is a BCM able to aggregate units of
bandwidth or kHz depending on how it's configured and this BCM is
configured for kHz?
Here's a link toThanks for the link. It looks like the IPA driver hard codes a rate of
the IPA driver implementation: https://lkml.org/lkml/2018/11/7/220
75 MHz.