From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Peter Chen <hzpeterchen@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>, Peter Chen <Peter.Chen@nxp.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Rajesh Bhagat <rajesh.bhagat@nxp.com>,
"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
lkml <linux-kernel@vger.kernel.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
linux-arm-msm <linux-arm-msm@vger.kernel.org>,
Li Yang <leoli@freescale.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] usb: chipidea: Configure DMA properties and ops from DT
Date: Fri, 18 Mar 2016 10:56:55 +0000 [thread overview]
Message-ID: <20160318105655.GE19428@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <20160318015414.GA30851@shlinux2.ap.freescale.net>
On Fri, Mar 18, 2016 at 09:54:14AM +0800, Peter Chen wrote:
> Although I don't know what kinds of bugs it may have, it may be
> met before, otherwise, why most of platform drivers need to call
> dma_set_coherent_mask or dma_coerce_mask_and_coherent explicitly
See Documentation/DMA-API.txt, specifically the section starting
Part Ic - DMA addressing limitations
------------------------------------
and also Documentation/DMA-API-HOWTO.txt, the section on
DMA addressing limitations
which provides further information.
Drivers using DMA should be using dma_set_mask_and_coherent() _or_
one of dma_set_mask() and dma_set_coherent_mask() depending on which
types of DMA they wish to perform. Drivers should not use
dma_coerce_mask_and_coherent() except in exceptional circumstances:
that function is more a marker that they or some bus/platform code
is doing something wrong.
--
RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.
next prev parent reply other threads:[~2016-03-18 10:57 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-22 5:32 [PATCH] usb: chipidea: Configure DMA properties and ops from DT Bjorn Andersson
2016-02-22 6:02 ` Peter Chen
2016-02-22 6:14 ` Bjorn Andersson
2016-02-22 10:03 ` Srinivas Kandagatla
2016-02-22 22:07 ` Bjorn Andersson
2016-02-23 1:31 ` Peter Chen
2016-03-02 22:59 ` Li Yang
2016-03-08 19:52 ` Li Yang
2016-03-09 3:40 ` Bjorn Andersson
2016-03-09 23:16 ` Li Yang
2016-03-14 10:51 ` Peter Chen
2016-03-17 15:52 ` Arnd Bergmann
2016-03-18 1:54 ` Peter Chen
2016-03-18 3:25 ` Rajesh Bhagat
2016-03-18 7:28 ` Arnd Bergmann
2016-03-18 10:56 ` Russell King - ARM Linux [this message]
2016-03-25 4:02 ` Peter Chen
2016-03-25 4:39 ` [PATCH 1/1] usb: chipidea: add DMA mask configuration API kbuild test robot
2016-10-21 16:59 ` [RESEND PATCH] usb: chipidea: Configure DMA properties and ops from DT Bjorn Andersson
2016-10-21 17:38 ` Stephen Boyd
2016-10-21 17:53 ` Bjorn Andersson
2016-10-22 6:22 ` Sriram Dash
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