From: Michael Schmitz <schmitzmic@gmail.com>
To: Finn Thain <fthain@telegraphics.com.au>
Cc: Sam Creasey <sammy@sammy.net>,
Christoph Hellwig <hch@infradead.org>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Linux/m68k <linux-m68k@vger.kernel.org>
Subject: Re: Sun3 SCSI DMA, was Re: converting the NCR5380 drivers away from scsi_register
Date: Fri, 15 Aug 2014 13:51:25 +1200 [thread overview]
Message-ID: <CAOmrzk+1JAKOrSjQGRdeyooKdP+LHxyTt8uSOKV_N7A5qLZfxQ@mail.gmail.com> (raw)
In-Reply-To: <alpine.LNX.2.00.1408151138260.28678@nippy.intranet>
Hi Finn,
On Fri, Aug 15, 2014 at 1:46 PM, Finn Thain <fthain@telegraphics.com.au> wrote:
>
> On Thu, 14 Aug 2014, Michael Schmitz wrote:
>
>> >
>> > > > When cmd->device->borken, I assume sun3_NCR5380 inhibits PIO
>> > > > because PIO was itself expected to be problematic?
>> > > >
>>
>> The sun3 driver does set the borken flag but never uses it later - can't
>> see where it will inhibit PIO.
>
> It inhibited PIO when it forked the atari code and commented out the test
> for cmd->device->borken, to ensure that PIO would never be used here.
I see. I just tool that to mean the Sun3 driver never had trouble with
devices failing at that section, so no need to switch from DMA to PIO
(because DMA never fails).
> Hence my suggestion that PIO itself was expected was problematic. OTOH,
> PIO is used up to 128 bytes, and beyond 128 bytes if !REQ_TYPE_FS...
Up to 128 for DMA limitations - the other bit I don't understand either.
Cheers,
Michael
> --
next prev parent reply other threads:[~2014-08-15 1:51 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-16 14:18 converting the NCR5380 drivers away from scsi_register Christoph Hellwig
2014-06-17 8:20 ` Finn Thain
2014-06-17 8:38 ` Geert Uytterhoeven
2014-07-30 8:32 ` Finn Thain
2014-07-31 5:31 ` Michael Schmitz
2014-08-01 3:13 ` Finn Thain
2014-08-01 8:15 ` Michael Schmitz
2014-08-02 1:27 ` Finn Thain
2014-08-02 8:51 ` Michael Schmitz
2014-08-03 3:43 ` Finn Thain
2014-08-03 9:07 ` Michael Schmitz
2014-08-04 3:28 ` Finn Thain
2014-08-05 9:06 ` Michael Schmitz
2014-08-06 1:25 ` Sun3 SCSI DMA, was " Finn Thain
2014-08-06 14:42 ` Sam Creasey
2014-08-08 8:46 ` Michael Schmitz
2014-08-11 15:10 ` Sam Creasey
2014-08-13 5:29 ` Finn Thain
2014-08-13 9:14 ` Michael Schmitz
2014-08-14 1:43 ` Finn Thain
2014-08-14 8:57 ` Michael Schmitz
2014-08-15 1:46 ` Finn Thain
2014-08-15 1:51 ` Michael Schmitz [this message]
2014-08-15 2:09 ` Finn Thain
2014-08-15 3:03 ` Michael Schmitz
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