Re: [PATCH] opp: fix dev_pm_opp_set_rate for different frequency at the same opp level

[Jonathan Marek]

On 2/16/21 11:53 PM, Viresh Kumar wrote:
> On 16-02-21, 15:10, Jonathan Marek wrote:
> > There is not "nothing to do" when the opp is the same. The frequency can
> > be different from opp->rate.
>
> I am sorry but I am not sure what are you trying to fix here and what exactly is
> broken here. Can you provide a usecase for your platform where this doesn't work
> like it used to ?

The specific case is this opp table:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/boot/dts/qcom/sm8250.dtsi#n439

It does not define every possible clock frequency, it only defines the 
rates at which a higher rpmhpd level must be used. Which is the intended 
use of opp.

Your change broke this completely: the clock rate change can be silently 
ignored because the opp level is the same. In particular it breaks 
bluetooth for this platform.

> > Fixes: 81c4d8a3c414 ("opp: Keep track of currently programmed OPP")
> > Signed-off-by: Jonathan Marek <jonathan@xxxxxxxx>
> > ---
> >   drivers/opp/core.c | 7 +++++--
> >   drivers/opp/opp.h  | 1 +
> >   2 files changed, 6 insertions(+), 2 deletions(-)