From: Feng Tang <feng.tang@intel.com>
To: David Brownell <david-b@pacbell.net>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Greg KH <greg@kroah.com>,
spi-devel-list <spi-devel-general@lists.sourceforge.net>,
"linux-serial@vger.kernel.org" <linux-serial@vger.kernel.org>,
Grant Likely <grant.likely@secretlab.ca>,
"alan@lxorguk.ukuu.org.uk" <alan@lxorguk.ukuu.org.uk>
Subject: Re: [PATCH v5] serial: spi: add spi-uart driver for Maxim 3110
Date: Wed, 3 Mar 2010 15:42:29 +0800 [thread overview]
Message-ID: <20100303154229.5d0f3633@feng-i7> (raw)
In-Reply-To: <201003022325.52315.david-b@pacbell.net>
On Wed, 3 Mar 2010 15:25:52 +0800
David Brownell <david-b@pacbell.net> wrote:
> If someone decided to update a SPI controller driver to avoid DMA in
> some cases, in favor of PIO, they could already code such heuristics
> without needing your proposed hinting from upper layers.
>
> The result in the low-level driver would be just to use a different
> test (maybe "is this a one-word transfer?" instead of checking your
> per-transfer "use PIO?" hint)
Yup, good point, controller driver can be smarter
Thanks,
Feng
> before kicking in whatever logic you
> think would improve performance (by eliminating DMA setup and teardown
> costs, including cache cleaning).
>
> - Dave
>
next prev parent reply other threads:[~2010-03-03 7:40 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-29 14:20 [RFC][PATCH] serial: spi: add spi-uart driver for Maxim 3110 Feng Tang
2009-12-29 14:59 ` [spi-devel-general] " Baruch Siach
2009-12-29 16:05 ` Tang, Feng
2009-12-29 18:43 ` Erwin Authried
2009-12-30 1:54 ` Feng Tang
2010-02-25 4:47 ` David Brownell
2010-02-25 7:49 ` Feng Tang
2009-12-29 15:02 ` Alan Cox
2010-02-08 8:59 ` [RFC][PATCH v2] " Feng Tang
2010-02-09 0:20 ` Andrew Morton
2010-02-09 0:26 ` Grant Likely
2010-02-09 1:36 ` Feng Tang
2010-02-17 22:58 ` Greg KH
2010-02-24 5:11 ` [RFC][PATCH v3] " Feng Tang
2010-02-24 10:44 ` Alan Cox
2010-02-24 14:25 ` Grant Likely
2010-02-24 23:18 ` Andrew Morton
2010-02-25 6:39 ` Feng Tang
2010-02-25 4:43 ` David Brownell
2010-02-25 7:44 ` Feng Tang
2010-02-25 8:11 ` David Brownell
2010-02-26 3:47 ` [PATCH v4] " Feng Tang
2010-02-26 3:47 ` Feng Tang
2010-02-26 9:59 ` Masakazu Mokuno
2010-02-26 19:41 ` David Brownell
2010-03-01 2:30 ` Feng Tang
2010-03-02 3:38 ` Feng Tang
2010-02-09 9:25 ` [RFC][PATCH v2] " Alan Cox
2010-03-03 2:57 ` [PATCH v5] " Feng Tang
2010-03-03 3:59 ` Grant Likely
2010-03-03 4:51 ` David Brownell
2010-03-03 5:52 ` Feng Tang
2010-03-03 6:16 ` David Brownell
2010-03-03 6:37 ` Feng Tang
2010-03-03 7:25 ` David Brownell
2010-03-03 7:42 ` Feng Tang [this message]
2010-02-08 8:59 ` [RFC][PATCH v2] " Feng Tang
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