Re: [PATCH v2 2/4] soc: qcom: rpmh: Add support to read back resource settings
From: Neil Armstrong
Date: Mon Oct 27 2025 - 10:41:48 EST
On 10/27/25 14:29, Konrad Dybcio wrote:
On 10/23/25 11:46 AM, Maulik Shah (mkshah) wrote:
On 10/23/2025 2:39 PM, Konrad Dybcio wrote:
On 10/23/25 10:57 AM, Maulik Shah (mkshah) wrote:
On 10/23/2025 1:47 PM, Konrad Dybcio wrote:
On 10/23/25 6:46 AM, Maulik Shah (mkshah) wrote:
On 10/23/2025 2:51 AM, Bjorn Andersson wrote:
On Wed, Oct 22, 2025 at 02:38:54AM +0530, Kamal Wadhwa wrote:
From: Maulik Shah <maulik.shah@xxxxxxxxxxxxxxxx>
All rpmh_*() APIs so far have supported placing votes for various
resource settings but the H/W also have option to read resource
settings.
This change adds a new rpmh_read() API to allow clients
to read back resource setting from H/W. This will be useful for
clients like regulators, which currently don't have a way to know
the settings applied during bootloader stage.
Allow me to express my disappointment over the fact that you sat on this
for 7 years!
This was a dead API (even in downstream) with no user since SDM845/ 7 years.
Read support was eventually removed from downstream driver too for the same reason.
There were early discussions to remove read support from RSC H/W, due to lack of users.
Its not realized yet and all SoCs still supports read.
Can we read BCM states from HLOS this way too?
Yes, Any of ARC/BCM/VRM can be read to get HLOS/DRV2 votes.
Wow this is amazing..
Do you have code for this already, or should I hack on it?
No, it won't be of much help, as i said above it gets HLOS/DRV2 votes only for a given resource.
More specifically, the read does not give the aggregated vote result across all the DRVs.
Hm, perhaps it could still be of *some* use
But maybe reading back rpmhpd and rpmhcc states would be of more
use!
The interconnect core definitely supports reading back the state at boot.
Neil
Konrad