Re: [PATCH V1 4/4] phy: qcom-qmp-ufs: read max-microamp values from device tree

[Krzysztof Kozlowski]

On Fri, Aug 08, 2025 at 02:15:31AM +0530, Nitin Rawat wrote:
> 
> 
> On 8/8/2025 12:15 AM, Mark Brown wrote:
> > On Thu, Aug 07, 2025 at 11:26:17PM +0530, Nitin Rawat wrote:
> > 
> > > 1. Regulator and PMIC configurations are board-specific, meaning they can
> > > vary significantly across different platforms. For example, some boards may
> > > use different generations of UFS devices — such as UFS 2.x — which come with
> > > distinct power and load requirements and some with UFS3.x which has it own
> > > power/load requirement.
> > 
> > Requirements from generations of UFS devices presumably come from the
> > UFS spec and should just be known though?
> > 
> > > 2. UFS PHY load and PMIC requirements also varies across targets, depending
> > > on the underlying technology node and the specific PHY capabilities. These
> > > differences can be influenced by the MIPI version or other implementation
> > > details.
> > 
> > If you've got non-enumerable PHYs that have a big impact that's a much
> > clearer use case for putting things in DT.
> 
> What I meant is that different boards may use different UFS parts, and the
> associated PHY load requirements are not governed by the UFS specification
> itself. Instead, these requirements depend on our specific PHY design and
> MIPI, which can vary across platforms.

The UFS controller knows which device it has attached - 2.x or 3.x - so
power considerations are known to the driver.

> 
> Because these characteristics — such as load requirements — are not
> enumerable or automatically detectable, it makes sense to describe them
> explicitly in the device tree. This approach ensures that board-specific
> variations are accurately captured without hardcoding them into the driver.

But you never came with rationale why given board has that value.

All this is done ONLY because downstream has it.

Best regards,
Krzysztof