Re: [PATCH] arm64: dts: qcom: sdm845-db845c: Mark cont splash memory region as reserved

[Dmitry Baryshkov]

On 09/02/2023 14:22, Bryan O'Donoghue wrote:
> On 09/02/2023 12:11, Bryan O'Donoghue wrote:
> > > If the bootloader splash is enabled then this memory is used until the
> > > DPU driver instructs MDP5 pipes to suck data from a newly assigned 
> > > address,
> > > so there's a short window where it is.
> >
> > It seems a shame to reserve 30 something megabytes of memory for 
> > continuous splash unless we are actually using it is my point.
> >
> > If I'm running headless its just wasted memory.
>
> Couldn't we
>
> 1. Find reserved continuous splash memory
> 2. Fee it in the MDP when we make the transition

Qualcomm has investigated freeing the MDP/DPU cont_splash memory, but I 
fear that the end result was that it is not _that_ easy to free it. It 
is marked as reserved/no-map, so the kernel doesn't think about it as a 
memory region. Adding it back required hacking around that.

--
With best wishes
Dmitry