Re: [PATCH 02/13] dt-bindings: clock: qcom,sm8550-dispcc: Add display CESTA support on SM8750

Dmitry Baryshkov
2026-04-28T18:56:23Z

On Tue, 28 Apr 2026 at 20:21, Jagadeesh Kona
<jagadeesh.kona@oss.qualcomm.com> wrote:
>
>
>
> On 4/20/2026 11:15 PM, Dmitry Baryshkov wrote:
> > On Mon, Apr 20, 2026 at 09:58:55PM +0530, Jagadeesh Kona wrote:
> >> On SM8750, a subset of DISPCC clocks is controlled by the display CESTA
> >> (Client State Aggregator) hardware. These clocks can be scaled to the
> >> desired frequency by sending votes to the display CRM(CESTA Resource
> >> manager) instead of programming DISPCC registers directly.
> >>
> >> Add bindings to allow the DISPCC node to reference the display CRM node
> >> for sending votes to CESTA hardware and the CRMC syscon regmap node
> >> which is used to read the frequency look up tables provided by CRM and
> >> populate this data in RCG's frequency tables for CESTA controlled clocks.
> >>
> >> Signed-off-by: Jagadeesh Kona <jagadeesh.kona@oss.qualcomm.com>
> >> ---
> >> .../bindings/clock/qcom,sm8550-dispcc.yaml | 48 ++++++++++++++++++++++
> >> 1 file changed, 48 insertions(+)
> >>
> >> diff --git a/Documentation/devicetree/bindings/clock/qcom,sm8550-dispcc.yaml b/Documentation/devicetree/bindings/clock/qcom,sm8550-dispcc.yaml
> >> index 591ce91b8d54dd6f78a66d029882bcd94b53beda..3e049b2160a1781c866bb30b29f0da5c9e156b61 100644
> >> --- a/Documentation/devicetree/bindings/clock/qcom,sm8550-dispcc.yaml
> >> +++ b/Documentation/devicetree/bindings/clock/qcom,sm8550-dispcc.yaml
> >> @@ -60,6 +60,18 @@ properties:
> >> A phandle to an OPP node describing required MMCX performance point.
> >> maxItems: 1
> >>
> >> + qcom,crm:
> >> + $ref: /schemas/types.yaml#/definitions/phandle
> >> + description:
> >> + Phandle to the display CRM (CESTA Resource Manager) node, used to communicate
> >> + with the display CESTA (Client State Aggregator) hardware.
> >
> > Is it going to be shared by several entities? If not, can be make a part
> > of the dispcc and get rid of the extra CC <-> CRM API?
> >
>
> Thanks Dmitry for your review.
>
> Yes, clock is one of the consumer of CRM, but CRM can be used by interconnect drivers also
> for BW voting via CESTA.
>
> >> +
> >> + qcom,crmc-regmap:
> >> + $ref: /schemas/types.yaml#/definitions/phandle
> >> + description:
> >> + Phandle to the syscon providing the CRMC (CRM clock) regmap used
> >> + to read frequency LUTs (lookup tables) populated by the CRM.
> >
> > Why is this coming as a syscon? Why isn't it just a register region of
> > the dispcc?
> >
>
> The CRMC block is not part of the DISPCC register region; it is a separate sub‑block within the
> CRM(CESTA) address space. It contains clocks frequency lookup tables that the clock driver reads
> to populate RCG frequency tables. Since CRMC block is outside of DISPCC region and DISPCC driver
> doesn't own or manage the CRMC block and uses it just to read CRM controlled RCG's frequency
> tables, marked it as a syscon device.

Why is it a syscon rather than a normal device with the normal driver?

--
With best wishes
Dmitry