Conversion of old Amiga NCR53C9x drivers to esp_scsi

Conversion of old Amiga NCR53C9x drivers to esp_scsi

[Kars de Jong]

Hello everyone,


After an initial failure in February this year I have now gotten my
Blizzard SCSI Kit IV to work with the esp_scsi core.

It turns out the DMA engine doesn't like a transfer size of only 2 bytes
(at least not when receiving). The bytes were in the FSC FIFO, but
didn't get transferred to DRAM and the final interrupt didn't occur so
the driver got stuck.

The old driver used to do such small transfers using PIO, so that is
what I do now in the glue driver.

What is the way to go? Revive the glue named drivers/scsi/blz1230.c?
Or should it be renamed?

Some of the other drivers may be a little more problematic because they
had more driver operations which are not present in the esp_scsi DMA
abstraction.


Kind regards,

Kars.

Re: Conversion of old Amiga NCR53C9x drivers to esp_scsi

[Michael Schmitz]

Hi,

> After an initial failure in February this year I have now gotten my
> Blizzard SCSI Kit IV to work with the esp_scsi core.

Congratulations!
 
> It turns out the DMA engine doesn't like a transfer size of only 2 bytes
> (at least not when receiving). The bytes were in the FSC FIFO, but
> didn't get transferred to DRAM and the final interrupt didn't occur so
> the driver got stuck.
> 
> The old driver used to do such small transfers using PIO, so that is
> what I do now in the glue driver.
> 
> What is the way to go? Revive the glue named drivers/scsi/blz1230.c?
> Or should it be renamed?

I'd rename it to blz1230_esp.c. 
 
> Some of the other drivers may be a little more problematic because they
> had more driver operations which are not present in the esp_scsi DMA
> abstraction.

Can you fall back to PIO for those cases? 

	Michael

Re: Conversion of old Amiga NCR53C9x drivers to esp_scsi

[David Miller]

From: Kars de Jong <jongk@linux-m68k.org>
Date: Mon, 24 Nov 2008 22:01:50 +0100

> What is the way to go? Revive the glue named drivers/scsi/blz1230.c?
> Or should it be renamed?
> 
> Some of the other drivers may be a little more problematic because they
> had more driver operations which are not present in the esp_scsi DMA
> abstraction.

Whatever tweaks you need to make to the DMA abstraction to make
your parts work are probably fine.  Get your hardware working
and then post your esp_scsi core changes for review here.

Re: Conversion of old Amiga NCR53C9x drivers to esp_scsi

[James Bottomley]

On Mon, 2008-11-24 at 22:01 +0100, Kars de Jong wrote:
> Hello everyone,
> 
> 
> After an initial failure in February this year I have now gotten my
> Blizzard SCSI Kit IV to work with the esp_scsi core.
> 
> It turns out the DMA engine doesn't like a transfer size of only 2 bytes
> (at least not when receiving). The bytes were in the FSC FIFO, but
> didn't get transferred to DRAM and the final interrupt didn't occur so
> the driver got stuck.

Oh, that's a known problem with some NCR chips.  The way the manual
recommends handling it as a PIO transaction to empty the DMA engine.
Checking whether this condition occurs can be tricky, though.

> The old driver used to do such small transfers using PIO, so that is
> what I do now in the glue driver.
> 
> What is the way to go? Revive the glue named drivers/scsi/blz1230.c?
> Or should it be renamed?

What I did when converting the 53c700 and 710 based drivers to the
generic core was simply to keep the old name and gut the innards of the
driver.  Whichever way you want to do it will be fine, though.

> Some of the other drivers may be a little more problematic because they
> had more driver operations which are not present in the esp_scsi DMA
> abstraction.

Any changes you need to make in the generic to support these, just post
here for review as a separate patch (and CC the esp_scsi maintainer:
Dave Miller).

James