linux-kernel - Re: g_NCR5380 PDMA, was Re: [PATCH 0/6] ncr5380: Miscellaneous minor patches

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Date:   Thu, 16 Feb 2017 23:18:51 +0100
From:   Ondrej Zary <linux@...nbow-software.org>
To:     Finn Thain <fthain@...egraphics.com.au>
Cc:     "James E.J. Bottomley" <jejb@...ux.vnet.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Michael Schmitz <schmitzmic@...il.com>,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: g_NCR5380 PDMA, was Re: [PATCH 0/6] ncr5380: Miscellaneous minor patches

On Tuesday 31 January 2017 02:31:45 Finn Thain wrote:
[...]
> Are you trying to figure out which commands are going to disconnect during
> a transfer? This is really a function of the firmware in the target; there
> are no good heuristics AFAICT, so the PDMA algorithm has to be robust.
> mac_scsi has to cope with this too.
>
> Does the problem go away when you assign no IRQ? When instance->irq ==
> NO_IRQ, the core driver will inhibit disconnect privileges.

Yes, it seems to run fine with IRQ/disconnect disabled.
With IRQ enabled, "dd if=/dev/sr0 of=anything" stops after a while. I get 
gated 53C80 IRQ, BASR=0x10, MODE=0x0e, STATUS=0x7c.

When I enable interrupts during PDMA (like the removed UNSAFE macro did), the 
problems go away. I see an IRQ after each pread call.
(had to disable "no 53C80 gated irq after transfer" and "no end dma signal" 
messages to reduce log spam)

-- 
Ondrej Zary