Hi Angelo,
On 9/12/24 15:52, AngeloGioacchino Del Regno wrote:
[snip]
The range should match the target device's Vin constraints; in this
case, it
should be no lower than the minimum working voltage of the Vgpu-in of
the Mali IP.
The drivers will be responsible of setting the lowest possible voltage for
enhanced efficiency (power saving), taking into account the fused chip
quality bits
(in this case, the MediaTek SVS driver!).
You should, at this point, check the constraints of SVS, as in, given a
reference
voltage (in this case, located in the GPU OPP table, the voltage
associated with
the lowest frequency of the GPU), what is the maximum voltage
*subtraction* that
SVS will do on the VGPU?
After the subtraction, may this voltage be lower than 0.546V? :-)
Thanks for the clear explanation. While there are no explicit constraint
in the maximum voltage subtraction in the SVS driver, I have
confirmed that the fuse data of MT8395 is written in a way that the SVS
driver would never go lower than the minimum recommended operating
voltage of DVDD_GPU in the datasheet[1], which supplies power to the
Mali IP.
I have sent patch v2 to remove the always-on property and add a note
about the fuse(eFuse) data in [2].
[1]:
https://mediatek-marketing.files.svdcdn.com/production/documents/MTK_MT8395_Application-Processor-Datasheet_v1.8.pdf?dm=1724252510
[2]: https://lkml.org/lkml/2024/9/12/285
Many thanks,
Pablo
