Re: [PATCH V4 8/8] arm64: dts: qcom: sm4450: add camera, display and gpu clock controller
From: Ajit Pandey
Date: Fri Jul 12 2024 - 08:32:03 EST
On 7/12/2024 5:52 PM, Konrad Dybcio wrote:
On 12.07.2024 11:53 AM, Ajit Pandey wrote:
On 7/11/2024 3:25 PM, Konrad Dybcio wrote:
On 3.07.2024 11:16 AM, Ajit Pandey wrote:
On 6/13/2024 1:11 PM, Konrad Dybcio wrote:
On 6/11/24 15:37, Ajit Pandey wrote:
Add device node for camera, display and graphics clock controller on
Qualcomm SM4450 platform.
Signed-off-by: Ajit Pandey <quic_ajipan@xxxxxxxxxxx>
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None of these nodes reference a power domain (which would usually be
CX/MX/MMCX). This way, the RPMhPDs will never be scaled.
The current upstream implementation only allows one power domain to be
scaled, but that's better than none (see other DTs for recent SoCs).
Konrad
SM4450 doesn't support MMCX and CX/MX domains will remain active so
power-domains property is actually not required for SM4450 clock nodes.
It's not only about them being active.. some PLLs require e.g. MX to be
at a certain level, or the system will be unstable
Konrad
With active I mean CX/MX rails will be default running at minimum level required for clock controllers. Adding power-domains property for CX/MX rails is like a redundant code as that will also scale such rails at default specified minimum level only. Also we hadn't added such property for other targets DT nodes to scale up CX/MX at minimum level.
What I mean here is that, the minimum level may not be enough. In such case
you would also add a required-opps = <&handle_to_rpmhpd_opp_level>
Konrad
Apologies, but could you please elaborate the use-case where minimum
level isn't enough ? I guess for clock controllers configuration min
level of CX/MX would be suffice, client will anyhow scale such rails to
higher levels depending on their use-case.
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Thanks, and Regards
Ajit