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From: Michael Schmitz <schmitzmic@gmail.com>
To: Kars de Jong <jongk@linux-m68k.org>
Cc: James Bottomley <jejb@linux.ibm.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	linux-scsi@vger.kernel.org, linux-m68k@vger.kernel.org
Subject: Re: [PATCH] zorro_esp: increase maximum dma length to 65536 bytes
Date: Mon, 11 Nov 2019 08:26:32 +1300
Message-ID: <8c356175-e490-68c0-6114-5192eedc3a4f@gmail.com> (raw)
In-Reply-To: <CACz-3rjUh8tcShX5OPi+37JvF8PqG-8AEf5uMQHjMynSaVa1gw@mail.gmail.com>

Hi Kars,

thanks for your patch!

On 10/11/19 10:01 PM, Kars de Jong wrote:
> Hi Michael,
>
> Op zo 10 nov. 2019 om 03:36 schreef Michael Schmitz <schmitzmic@gmail.com>:
>> All of the old board-specific drivers used a max transfer length of
>> 0x1000000, only the fastlane driver used 0xfffc.
> Yes, I also found this when checking the old drivers.
>
>> That lower limit might
>> be due to a DMA limitation on the fastlane board. We could accommodate
>> the different limit for this board by using a board-specific
>> dma_length_limit() callback...
> Yes, I think that's the best idea for now. Oktagon also used to have a
> different limit but that was never ported to the new ESP core.

I can't remember the details, but as far as I recall it, the Oktagon 
used pseudo-DMA rather than hardware DMA. At the time I started porting 
Zorro ESP drivers to the new core, pseudo-DMA code was available for Mac 
only, and no PIO transfer for data phases at all, so I decided to leave 
that out altogether.

Might be a lot easier now that Finn has moved the PIO support code into 
the core driver. Someone could start with a PIO mode driver and add PDMA 
later.

>>> case for any of the cards the zorro_esp drives, it might be better to
>>> lower the max length to 61440 (64k-4k) so the residual is a page.
>> For the benefit of keeping the code simple, and avoid retesting the
>> fastlane board, that might indeed be the better solution.
> But it's slower... :-P
I wonder what max. transfer size had been used so far, in the majority 
of cases. I hadn't observed this bug in my tests of the ESP driver on 
elgar. So it might not matter so much in practice.
> Also, I may be adding another board-specific version for the Blizzard
> 12x0 IV to enable 24-bit transfers, like the am53c974 driver does, in
> a later patch.

If we can differentiate between the Mark IV board and the Mark II board 
in a reliable way, fine. I can't remember whether I've had a report on 
that ever.

I'd suggest to change the transfer size limit to 60k in the first 
instance, and add board-specific tweaks as needed when you add 24 bit 
DMA support for the Mark IV.

Cheers,

     Michael

>
> Kind regards,
>
> Kars.

  reply index

Thread overview: 74+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-24 20:56 Amiga PCMCIA network card support Andreas 'count' Kotes
2019-10-25  7:25 ` Kars de Jong
2019-10-25 11:49   ` Andreas 'count' Kotes
2019-10-28  9:19     ` Kars de Jong
2019-10-28 11:08       ` John Paul Adrian Glaubitz
2019-10-28 13:00         ` Kars de Jong
2019-10-28 13:20           ` John Paul Adrian Glaubitz
2019-10-28 15:39             ` ESP SCSI driver (was: Amiga PCMCIA network card support) Kars de Jong
2019-10-28 18:32               ` Michael Schmitz
2019-10-29  9:37                 ` Kars de Jong
2019-10-29 20:20                   ` ESP SCSI driver Michael Schmitz
2019-10-29 22:05                   ` [PATCH] esp_scsi: Add support for FSC chip Kars de Jong
2019-10-30  0:23                     ` Michael Schmitz
2019-10-30  7:11                       ` Kars de Jong
2019-10-30 18:42                         ` Michael Schmitz
2019-10-30  0:31                     ` Finn Thain
2019-10-30  1:06                       ` Michael Schmitz
2019-10-30  7:25                         ` Kars de Jong
2019-10-30  8:45                           ` Geert Uytterhoeven
2019-10-30  9:08                             ` Kars de Jong
2019-10-30 18:34                               ` Michael Schmitz
2019-10-30 18:52                             ` Brad Boyer
2019-10-30  7:22                       ` Kars de Jong
2019-10-30 23:15                         ` Finn Thain
2019-11-12 18:57                     ` [PATCH 0/2] Some esp_scsi updates Kars de Jong
2019-11-12 18:57                       ` [PATCH 1/2] esp_scsi: Correct ordering of PCSCSI definition in esp_rev enum Kars de Jong
2019-11-12 23:07                         ` Finn Thain
2019-11-13  8:00                           ` Kars de Jong
2019-11-13 22:25                             ` Finn Thain
2019-11-13 14:22                         ` Christoph Hellwig
2019-11-13 15:03                           ` Kars de Jong
2019-11-12 18:57                       ` [PATCH 2/2] esp_scsi: Add support for FSC chip Kars de Jong
2019-11-12 23:18                         ` Finn Thain
2019-11-12 23:57                           ` Finn Thain
2019-11-13  9:30                           ` Kars de Jong
2019-11-13 22:24                             ` Finn Thain
2019-11-14 21:59                       ` [PATCH v2 0/2] Some esp_scsi updates Kars de Jong
2019-11-14 21:59                         ` [PATCH 1/2] esp_scsi: Correct ordering of PCSCSI definition in esp_rev enum Kars de Jong
2019-11-14 22:06                           ` Kars de Jong
2019-11-14 21:59                         ` [PATCH 2/2] esp_scsi: Add support for FSC chip Kars de Jong
2019-11-14 22:07                           ` Kars de Jong
2019-11-14 22:25                         ` [PATCH v3 0/2] Some esp_scsi updates Kars de Jong
2019-11-14 22:25                           ` [PATCH v2 1/2] esp_scsi: Correct ordering of PCSCSI definition in esp_rev enum Kars de Jong
2019-11-15  2:13                             ` Finn Thain
2019-11-15  7:04                               ` Kars de Jong
2019-11-14 22:25                           ` [PATCH v3 2/2] esp_scsi: Add support for FSC chip Kars de Jong
2019-11-15  2:09                             ` Finn Thain
2019-11-18 13:27                               ` Kars de Jong
2019-11-09 19:14                   ` [PATCH] zorro_esp: increase maximum dma length to 65536 bytes Kars de Jong
2019-11-09 20:12                     ` James Bottomley
2019-11-10  2:36                       ` Michael Schmitz
2019-11-10  9:01                         ` Kars de Jong
2019-11-10 19:26                           ` Michael Schmitz [this message]
2019-11-11  8:47                             ` Kars de Jong
2019-11-10 19:35                         ` James Bottomley
2019-11-12 17:55                           ` [PATCH v2] zorro_esp: Limit DMA transfers to 65536 bytes (except on Fastlane) Kars de Jong
2019-11-12 22:46                             ` Finn Thain
2019-11-13  2:27                             ` Martin K. Petersen
2019-11-12  9:34                         ` [PATCH] zorro_esp: increase maximum dma length to 65536 bytes Kars de Jong
2019-11-09 22:53                     ` Finn Thain
2019-11-10  9:06                       ` Kars de Jong
2019-10-28 23:38               ` ESP SCSI driver (was: Amiga PCMCIA network card support) Finn Thain
2019-10-29 11:52                 ` Kars de Jong
2019-10-29 20:16                   ` ESP SCSI driver Michael Schmitz
2019-10-28 22:31           ` Amiga PCMCIA network card support Finn Thain
2019-10-29  8:56           ` FOSDEM (was: Re: Amiga PCMCIA network card support) Geert Uytterhoeven
2019-10-29  9:13             ` John Paul Adrian Glaubitz
2019-10-28 22:08       ` Amiga PCMCIA network card support Finn Thain
2019-10-29  9:00       ` Geert Uytterhoeven
2019-10-29  9:12         ` John Paul Adrian Glaubitz
2019-10-29  9:14           ` Geert Uytterhoeven
2019-10-29  9:20             ` John Paul Adrian Glaubitz
2019-10-29  9:40         ` Kars de Jong
2019-10-28  6:57   ` Michael Schmitz

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