Re: [PATCH v5 2/4] soc: qcom: ice: Add OPP-based clock scaling support for ICE

[Abhinaba Rakshit <abhinaba.rakshit@oss.qualcomm.com>]

On Thu, Feb 19, 2026 at 03:20:31PM +0100, Konrad Dybcio wrote:
> On 2/18/26 8:02 PM, Abhinaba Rakshit wrote:
> > On Mon, Feb 16, 2026 at 01:18:57PM +0100, Konrad Dybcio wrote:
> >> On 2/13/26 8:02 AM, Abhinaba Rakshit wrote:
> >>> On Thu, Feb 12, 2026 at 12:30:00PM +0100, Konrad Dybcio wrote:
> >>>> On 2/11/26 10:47 AM, Abhinaba Rakshit wrote:
> >>>>> Register optional operation-points-v2 table for ICE device
> >>>>> and aquire its minimum and maximum frequency during ICE
> >>>>> device probe.
> 
> [...]
> 
> >>> However, my main concern was for the corner cases, where:
> >>> (target_freq > max && ROUND_CEIL)
> >>> and
> >>> (target_freq < min && ROUND_FLOOR)
> >>> In both the cases, the OPP APIs will fail and the clock remains unchanged.
> >>
> >> I would argue that's expected behavior, if the requested rate can not
> >> be achieved, the "set_rate"-like function should fail
> >>
> >>> Hence, I added the checks to make the API as generic/robust as possible.
> >>
> >> AFAICT we generally set storage_ctrl_rate == ice_clk_rate with some slight
> >> play, but the latter never goes above the FMAX of the former
> >>
> >> For the second case, I'm not sure it's valid. For "find lowest rate" I would
> >> expect find_freq_*ceil*(rate=0). For other cases of scale-down I would expect
> >> that we want to keep the clock at >= (or ideally == )storage_ctrl_clk anyway
> >> so I'm not sure _floor() is useful
> > 
> > Clear, I guess, the idea is to ensure ice-clk <= storage-clk in case of scale_up
> > and ice-clk >= storage-clk in case of scale_down.
> 
> I don't quite understand the first case (ice <= storage for scale_up), could you
> please elaborate?

Here I basically mean to say is that, as you mentioned "we generally set
storage_ctrl_rate == ice_clk_rate, but latter never goes above the FMAX of the former".
I guess, the ideal way to handle this is to ensure using _floor when we want to scale_up.
This ensures the ice_clk does not vote for more that what storage_ctrl is running on.

Also, this avoids the corner case, where target_freq provided is higher that the supporter
rates (descriped in ICE OPP-table) for ICE, using _ceil makes no sense.

Abhinaba Rakshit