linux-kernel - Re: [PATCH v4 34/78] atari_NCR5380: Use arbitration timeout

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Message-ID: <CAOmrzkLccCjboTpQo05UjDr=Evwd_nF7e3SK+r2y3zkzTjdh_g@mail.gmail.com>
Date:	Tue, 26 Jan 2016 08:56:26 +1300
From:	Michael Schmitz <schmitzmic@...il.com>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:	Finn Thain <fthain@...egraphics.com.au>,
	"James E.J. Bottomley" <JBottomley@...n.com>,
	"Martin K. Petersen" <martin.petersen@...cle.com>,
	"Linux/m68k" <linux-m68k@...r.kernel.org>,
	scsi <linux-scsi@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 34/78] atari_NCR5380: Use arbitration timeout

Hi Geert,

On Mon, Jan 25, 2016 at 9:05 PM, Geert Uytterhoeven
<geert@...ux-m68k.org> wrote:

>>> Perhaps this is an ARAnyM quirk?
>
>> The MR_ARBITRATE bit should remain set until the driver clears it (or the
>> reset logic clears it). But it looks like aranym simply discards writes to
>> the mode register, such that reads always return 0.
>>
>> Compare
>>   http://sourceforge.net/p/aranym/code/ci/master/tree/src/ncr5380.cpp
>> with the MAME/MESS emulated device
>>   https://github.com/mamedev/mame/blob/master/src/devices/machine/ncr5380.cpp
>>
>> I don't know what the Hatari emulator does.
>>
>> In principle I think that Linux drivers should not carry workarounds for
>> emulators.
>
> Please consider ARAnyM is the current m68k workhorse, so it would be
> nice to handle this someway.
>
> Alternatively, we need to fix ARAnyM, or can make the creation of the
> atari_scsi platform device conditional on not running under ARAnyM.

Should be possible based on the machine cookie, unless that gets
munged by kernel startup code.

(Making the 5380 emulation a bit more complete such as in the MAME
source snippet would be my preference, too)

Cheers,

  Michael


>
> Thanks!
>
> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds