From mboxrd@z Thu Jan 1 00:00:00 1970 From: stillcompiling@gmail.com (Joshua Clayton) Date: Tue, 17 Nov 2015 10:58:54 -0800 Subject: [PATCH 1/8] Documentation/spi/spidev_test.c: use one rx buffer In-Reply-To: <20151117174156.GX31303@sirena.org.uk> References: <2f17ae29e75967b4522b080c275b907622e1d353.1447773299.git.stillcompiling@gmail.com> <20151117174156.GX31303@sirena.org.uk> Message-ID: <2858640.EtAPBOce2G@jclayton-pc> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tuesday, November 17, 2015 05:41:56 PM Mark Brown wrote: > On Tue, Nov 17, 2015 at 07:24:21AM -0800, Joshua Clayton wrote: > > > default_rx and rx are needlessly different. > > Use one buffer, local to transmit() > > Why? This isn't what I'd expect from black boxing the API, from a > userspace point of view the transfer is atomic and in an ideal world > we'd be able to do direct to/from memory transfers rather than memcpy() > into kernel space which means that userspace should assume the transfers > are going on simultaneously even if they don't currently. The important thing here was to get rid of the default_rx buffer. I just noticed that the output can be set up completely within the scope of the transmit function, since the operands are global. But I would be just as happy to set it up at the top level. I'll change this in V2 -- ~Joshua Clayton