[PATCH 2/2] drm/etnaviv: fix power register offset on GC300

[Lucas Stach]

Hi Doug,

Am Montag, dem 05.09.2022 um 14:05 -0700 schrieb Doug Brown:
> Hi Christian,
> 
> On 9/3/2022 4:49 AM, Christian Gmeiner wrote:
> 
> > I had a quick look at what vivantes kernel driver did. It uses a per
> > gpu instance variable powerBaseAddress
> > that gets set accordingly. I am not sure if I really like the
> > gpu_fix_reg_address(..) idea, as it gets called on every
> > register read and write. For me I see two other possible solutions:
> > 
> > 1) Add two seperate helpers ala gpu_read_power() and gpu_write_power()
> > where we do the if beast.
> > 2) Add a power register offset variable to etnaviv_gpu and explicitly
> > use it on for reads and writes - like the Vivante driver does.
> > 
> > But that's just my personal opinion. Can't wait to hear what Lucas thinks.
> > 
> 
> Thanks for reviewing so fast! I honestly agree. It felt kind of dirty
> modifying gpu_write and gpu_read. The reason I went for it is I was
> thinking that in most cases the compiler is going to optimize the ugly
> "if" out.
> 
> The two solutions listed above both sound good. They would need a
> special case in etnaviv_core_dump_registers, but that's probably much
> less nasty than modifying gpu_read and gpu_write. Any preferences from
> everyone on which of the other two options I should do? The
> gpu_read_power and gpu_write_power approach sounds pretty clean to me.

Yes, please add a specialized wrapper for the power register accesses.

Regards,
Lucas