Re: [PATCH] powerpc/85xx: use the BRx registers to enable indirect mode on the P1022DS

On Jul 5, 2012, at 10:08 AM, Timur Tabi wrote:

In order to enable the DIU video controller on the P1022DS, the FPGA =

needs

to be switched to "indirect mode", where the localbus is disabled and
the FPGA is accessed via writes to localbus chip select signals CS0 =

and CS1.

=20
To obtain the address of CS0 and CS1, the platform driver uses an =

"indirect

pixis mode" device tree node.  This node assumes that the localbus =

'ranges'

property is sorted in chip-select order.  That is, reg value 0 maps to
CS0, reg value 1 maps to CS1, etc.  This is how the 'ranges' property =

is

supposed to be arranged.
=20
Unfortunately, the 'ranges' property is often mis-arranged, and not =

just on

the P1022DS.  Linux normally does not care, since it does not program =

the

localbus.  But the indirect-mode code on the P1022DS does care.
=20
The "proper" fix is to have U-Boot fix the 'ranges' property, but this =

would

be too cumbersome.  The names and 'reg' properties of all the localbus
devices would also need to be updated, and determining which localbus =

device

maps to which chip select is board-specific.
=20
Instead, we determine the CS0/CS1 base addresses the same way that =

U-boot

does -- by reading the BRx registers directly and mapping them to =

physical

addresses.  This code is simpler and more reliable, and it does not =

require

a U-boot or device tree change.
=20
Since the indirect pixis device tree node is no longer needed, the =

node is

deleted from the DTS.
=20
Signed-off-by: Timur Tabi <redacted>
---
arch/powerpc/boot/dts/p1022ds.dtsi     |   16 -----
arch/powerpc/platforms/85xx/p1022_ds.c |  106 =

++++++++++++++++++++++++++++----

2 files changed, 93 insertions(+), 29 deletions(-)

applied to next

- k=