From: Michael Schmitz <schmitzmic@gmail.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
linux-scsi@vger.kernel.org, linux-m68k@vger.kernel.org
Subject: Re: [PATCH] scsi: gvp11: add module parameter for DMA transfer bit mask
Date: Wed, 30 Aug 2023 19:52:09 +1200 [thread overview]
Message-ID: <b4e22628-9e5f-c635-93a2-7b24d546afed@gmail.com> (raw)
In-Reply-To: <CAMuHMdU-VmQcH+envdwFpRmMF2RpdZb3FE60u1RPROXwWzsbMw@mail.gmail.com>
Hi Geert
Am 30.08.2023 um 19:32 schrieb Geert Uytterhoeven:
> Hi Michael,
>
> On Wed, Aug 30, 2023 at 12:26 AM Michael Schmitz <schmitzmic@gmail.com> wrote:
>> On 30/08/23 10:05, Arnd Bergmann wrote:
>>> On Tue, Aug 29, 2023, at 17:45, Michael Schmitz wrote:
>>>> SCSI boards on Amiga. There now is no way to set a non-default
>>>> DMA mask on these boards.
>>> It might help to mention here in which cases the default mask
>>> is actually wrong.
>>
>> All I have is:
>>
>> 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.
>>
>> from Geert's reply. I can add that. It just did sound a shade
>> speculative...
>
> Apparently gvp11_setup() became unused in 2.3.13pre2 (in 1999), when all
> *_setup() functions were removed from init/main.c, and some of them were
> reimplemented using __setup() in the driver sources where they belonged.
But that wasn't done for gvp11_setup() ...
>>>> +module_param(gvp11_xfer_mask, int, 0444);
>>>> +MODULE_PARM_DESC(gvp11_xfer_mask, "DMA mask (0xff000000 == 24 bit DMA)");
>>>> +
>>> I think the comment is the wrong way round, it should be
>>> 0x00ffffff in this case, which also matches the default
>>> mask for ZORRO_PROD_GVP_SERIES_II, in the match table:
>>>
>>> static struct zorro_device_id gvp11_zorro_tbl[] = {
>>> { ZORRO_PROD_GVP_COMBO_030_R3_SCSI, ~0x00ffffff },
>>> { ZORRO_PROD_GVP_SERIES_II, ~0x00ffffff },
>>> { ZORRO_PROD_GVP_GFORCE_030_SCSI, ~0x01ffffff },
>>> { ZORRO_PROD_GVP_A530_SCSI, ~0x01ffffff },
>>> { ZORRO_PROD_GVP_COMBO_030_R4_SCSI, ~0x01ffffff },
>>> { ZORRO_PROD_GVP_A1291, ~0x07ffffff },
>>> { ZORRO_PROD_GVP_GFORCE_040_SCSI_1, ~0x07ffffff },
>>> { 0 }
>>> };
>
> The default masks above were added (in some other form) in 2.1.91pre1
> (in 1998). Before, people had to use gvp11_setup() to do that.
... because gvp11_setup() was already obsolete.
Thanks for dredging up that bit of history!
> So I think it is safe to assume there is no longer a need to configure
> this manually.
I'll take your word for that. No need to apply this patch, then!
(Apologies for the noise, Arnd ...)
Cheers,
Michael
> Gr{oetje,eeting}s,
>
> Geert
>
prev parent reply other threads:[~2023-08-30 18:38 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-29 21:45 [PATCH] scsi: gvp11: add module parameter for DMA transfer bit mask Michael Schmitz
2023-08-29 22:05 ` Arnd Bergmann
2023-08-29 22:25 ` Michael Schmitz
2023-08-30 0:14 ` Arnd Bergmann
2023-08-30 0:47 ` Michael Schmitz
2023-08-30 7:32 ` Geert Uytterhoeven
2023-08-30 7:52 ` Michael Schmitz [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=b4e22628-9e5f-c635-93a2-7b24d546afed@gmail.com \
--to=schmitzmic@gmail.com \
--cc=arnd@arndb.de \
--cc=geert@linux-m68k.org \
--cc=linux-m68k@vger.kernel.org \
--cc=linux-scsi@vger.kernel.org \
--cc=martin.petersen@oracle.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).