[parisc-linux] Re: NCR53c720

[Matthew Wilcox]

On Mon, Sep 29, 2003 at 11:25:01PM +0200, Rene Brothuhn wrote:
> I'm the one who getting the 53c770 driver working on APUS. The driver is 

Good to hear from you.  Let me just clear up a couple of
misunderstandings...

> based on the code from the ncr53c8xx driver which I found on a 2.4.16 
> kernel (maybe it was an other kernel version, I'm not really sure 
> anymore). In newer kernels the ncr53c8xx drivers are replaced by sym53c8xx 
> which uses a different and more complicated architecture.

The sym53c8xx driver doesn't support all the chips that ncr53c8xx
supported (mostly earlier chips like 810).  Now there's the sym53c8xx_2
driver that supports all the 8xx chips.  In 2.6, we've now eliminated all
PCI stuff from ncr53c8xx (and it should probably be renamed to ncr53c7xx,
but I actually have a slightly different plan for renaming it that needs
other work to happen first).

> In my opinion, the best is to create a seperate 53c720/770 driver based on 
> the 53c770 from APUS or ncr53c8xx. I guess the 53c770 from APUS should 
> work (with some changes) on a 720 (or similar), because the 770 was 
> designed to replace the 720. But I don't know anything about 735 and 755.

The HP 735/755 workstations have an NCR720 chip as part of their `core
IO'.  It appears as a parisc_device.  They have a PCX-T CPU which has
no way to allocate coherent memory.

> But the APUS driver is a really big "patchwork", has some problems and 
> needs a clean-up. And I haven't worked on the driver since a year due to 
> lack of time, sorry.
> 
> I still have lack of time, but if there are any questions, I will help. It 
> will be nice to have a native 720/770 driver... And maybe, if someone 
> tries to port this driver to a PA, I have to go for it...

OK.  I think the right path forward here is:

 - I port the ncr53c8xx to use the non-coherent DMA interfaces.
 - Someone converts the zorro device to embed the struct device.
 - Someone implements the non-coherent DMA interfaces for PowerPC.
 - Someone adds a zorro720 driver (see NCR_Q720 and zalon for inspiration)
   that's simply a glue layer from zorro to ncr720.

-- 
"It's not Hollywood.  War is real, war is primarily not about defeat or
victory, it is about death.  I've seen thousands and thousands of dead bodies.
Do you think I want to have an academic debate on this subject?" -- Robert Fisk