From: James Bottomley <jejb@linux.ibm.com>
To: Michael Schmitz <schmitzmic@gmail.com>,
Kars de Jong <jongk@linux-m68k.org>,
"Martin K. Petersen" <martin.petersen@oracle.com>
Cc: linux-scsi@vger.kernel.org, linux-m68k@vger.kernel.org
Subject: Re: [PATCH] zorro_esp: increase maximum dma length to 65536 bytes
Date: Sun, 10 Nov 2019 11:35:13 -0800 [thread overview]
Message-ID: <1573414513.3230.4.camel@linux.ibm.com> (raw)
In-Reply-To: <6b914b12-cbc7-6fe6-7cba-3e89b2f6f19b@gmail.com>
On Sun, 2019-11-10 at 15:36 +1300, Michael Schmitz wrote:
> All of the old board-specific drivers used a max transfer length of
> 0x1000000, only the fastlane driver used 0xfffc. 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...
Sure, that implies the minimum dma burst length is 4 bytes ...
> > 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.
... which means you don't have to lower the limit by 4k as I suggested,
because I was being incredibly conservative about what the dma burst
length might be, just use 0xfffc as the default. I think raising to
0x1000000 for boards which can support it is fine too if you want to
add the extra logic to the driver.
James
next prev parent reply other threads:[~2019-11-10 19:35 UTC|newest]
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
2019-11-11 8:47 ` Kars de Jong
2019-11-10 19:35 ` James Bottomley [this message]
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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