Re: [PATCH] scsi: gvp11: add module parameter for DMA transfer bit mask

Michael Schmitz
2023-08-30T18:38:08Z

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
>