Subject: Re: (subset) [PATCH 00/17] -Wmissing-prototype warning fixes

From: Michael Schmitz <[email-masked]>
Date: Sat, 26 Aug 2023 10:44:13 +1200

Hi Geert,

Am 25.08.23 um 19:39 schrieb Geert Uytterhoeven:
> Hi Michael,
>
> On Fri, Aug 25, 2023 at 3:31 AM Michael Schmitz <[email-masked]> wrote:
>> On 25/08/23 13:12, Martin K. Petersen wrote:
>>> [11/17] scsi: gvp11: remove unused gvp11_setup() function
>>>          https://git.kernel.org/mkp/scsi/c/bfaa4a0ce1bb
>> I somehow missed that one ...
>>
>> The gvp11_setup() function was probably a relic from the times before
>> module parameters.
>>
>> Since gvp11_xfer_mask appears to be required for some Amiga systems to
>> set the DMA mask, I'd best send a patch to add such a module parameter ...
>>
>> Do you know any details around the use of DMA masks for Amiga WD33C93
>> drivers, Geert?
> Doh, it's been a while, and I never had an affected system.
> Probably it's needed on A2000 with an accelerator card and GVP II SCSI,
> to prevent DMA to RAM banks that do not support fast DMA cycles.

Thanks, that's good enough for me.

Linux 2.0 had this comment:

|/* * DMA transfer mask for GVP Series II SCSI controller. * Some
versions can only DMA into the 24 bit address space * (0->16M). Others
can DMA into the full 32 bit address * space. The default is to only
allow DMA into the 24 bit * address space. The "gvp11=0xFFFFFFFE" setup
parameter can * be supplied to force an alternate (32 bit) mask. */ |

|We now handle that (since 2.6.35) through masks defined in
gvp11_zorro_tbl[] (though I note these don't account for unaligned
addresses such as implied by the example in the comment. Are unaligned
DMA buffers still possible today?). Would that cover the 'A2000 with
accelerator' case?
|

||

I'm happy to send a patch if an override to the device default DMA mask
is still necessary.

(Incidentally - did you ever publish the m68k full history tree anywhere
in git?)

Cheers,

    Michael

> Gr{oetje,eeting}s,
>                         Geert