From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joshua Clayton Subject: Re: [PATCH 1/8] Documentation/spi/spidev_test.c: use one rx buffer Date: Tue, 17 Nov 2015 10:58:54 -0800 Message-ID: <2858640.EtAPBOce2G@jclayton-pc> References: <2f17ae29e75967b4522b080c275b907622e1d353.1447773299.git.stillcompiling@gmail.com> <20151117174156.GX31303@sirena.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: Mark Brown , Jonathan Corbet , Adrian Remonda , linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org Return-path: In-Reply-To: <20151117174156.GX31303-GFdadSzt00ze9xe1eoZjHA@public.gmane.org> Sender: linux-spi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: 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 -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html