Re: [PATCH 4/9] arm64: dts: qcom: msm8916: Reserve firmware memory dynamically

[Bryan O'Donoghue]

On 13/09/2023 10:06, Konrad Dybcio wrote:
> On 11.09.2023 19:41, Stephan Gerhold wrote:
> > Most of the reserved firmware memory on MSM8916 can be relocated when
> > respecting the required alignment. To avoid having to precompute the
> > reserved memory regions in every board DT, describe the actual
> > requirements (size, alignment, alloc-ranges) using the dynamic reserved
> > memory allocation.
> >
> > This approach has several advantages:
> >
> >   1. We can define "templates" for the reserved memory regions in
> >      msm8916.dtsi and keep only device-specific details in the board DT.
> >      This is useful for the "mpss" region size for example, which varies
> >      from device to device. It is no longer necessary to redefine all
> >      firmware regions to shift their addresses.
> >
> >   2. When some of the functionality (e.g. WCNSS, Modem, Venus) is not
> >      enabled or needed for a device, the reserved memory can stay
> >      disabled, freeing up the unused reservation for Linux.
> >
> >   3. Devices with special requirements for one of the firmware regions
> >      are handled automatically. For example, msm8916-longcheer-l8150
> >      has non-relocatable "wcnss" firmware that must be loaded exactly
> >      at address 0x8b600000. When this is defined as a static region,
> >      the other dynamic allocations automatically adjust to a different
> >      place with suitable alignment.
> >
> > All in all this approach significantly reduces the boilerplate necessary
> > to define the different firmware regions, and makes it easier to enable
> > functionality on the different devices.
> >
> > Signed-off-by: Stephan Gerhold <stephan@xxxxxxxxxxx>
> > ---
> [...]
>
> >   
> >   		mpss_mem: mpss@86800000 {
> > +			/*
> > +			 * The memory region for the mpss firmware is generally
> > +			 * relocatable and could be allocated dynamically.
> > +			 * However, many firmware versions tend to fail when
> > +			 * loaded to some special addresses, so it is hard to
> > +			 * define reliable alloc-ranges.
> > +			 *
> > +			 * alignment = <0x0 0x400000>;
> > +			 * alloc-ranges = <0x0 0x86800000 0x0 0x8000000>;
> > +			 */
> Do we know of any devices that this would actually work on?
>
> Konrad

I have the same question here.

How was this tested ?

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bod