[PATCH v2 3/3] ARM: orion5x: Add D-Link DNS-323 based on Device Tree

[maukka at ext.kapsi.fi]

On 23.9.2022 21:02, Pali Rohár wrote:
> On Friday 23 September 2022 14:12:24 Andrew Lunn wrote:
>> > > > +	if (of_machine_is_compatible("dlink,dns323a1")) {
>> > > > +		writel(0, MPP_DEV_CTRL);		/* DEV_D[31:16] */
>> > >
>> > > I spotted this in dns323-setup.c as well. Do you have any idea what it
>> > > does?
>> > >
>> >
>> > No idea. I have tried to replicate what was in dns323-setup.c as exactly as
>> > possible.
>> > I can try to leave it out and see if anything changes.
>> 
>> It is best to keep what we don't understand. It will be there for a
>> reason.
>> 
>> 	Andrew
> 
> Hello! I tried to index all publicly available Marvell SoC
> documentations into kernel documentation subfolder:
> https://docs.kernel.org/arm/marvell.html
> 
> For Orion there is linked Datasheet and User Manual, so you could try 
> to
> find in those documents that mentioned register and check what it is
> doing.

MPP_DEV_CTRL refers to register at address 0x10008. According to the 
88F5152 user manual it's
'Device Multiplex Control Register' Offset: 0x10008.

Bits    Field     Type/InitVal     Description
[31:0]  Reserved  RES 0x03FF0000   Reserved. NOTE: Must be 0x03FF0000'.

DEV_D[31:16] receives no hits in the documentation, only to DEV_D[15:0] 
are referred.

Maybe 88F5151 is different, hard to say.