From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Nelson Date: Tue, 01 Oct 2013 08:56:11 -0700 Subject: [U-Boot] [PATCH] mx6: Add IOMUX_CONFIG_SION flag to all GPIO pins In-Reply-To: <524AE107.1050404@denx.de> References: <1380492900-910-1-git-send-email-otavio@ossystems.com.br> <524A88F2.9000903@denx.de> <524ACA60.3020504@denx.de> <524ADB98.9010605@boundarydevices.com> <524AE107.1050404@denx.de> Message-ID: <524AF09B.7040505@boundarydevices.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi Stefano, On 10/01/2013 07:49 AM, Stefano Babic wrote: > Hi Eric, > > On 01/10/2013 16:26, Eric Nelson wrote: > >> I'm not sure where you're seeing this in the RM, but in >> order to read the pad state when not configured as an input, >> the SION bit needs to be set in the pad mux register on i.MX51/53. > > I have checked inside the "37.3.2.2 GPIO Write" for i.MX53 and " > 35.4.2.1 Read Value from Pad" for i:MX51, I have not read anything about > SION. If someone has found where it is described, please mail ! > That documentation seems to imply that there's no dependency (i.e. there's no reference to SION), but I think that's an omission. >> >> FWIW, this also works when not muxed as a GPIO, which is really >> handy for verifying that a PWM is toggling, et cetera. > > Well, if you have directly tested it, it is better proofed as by the > manuals..then we need the same fix for i.MX51/i.MX53, too. > I've tested this many times, since it's a really handy way of debugging hardware setups. That said, I'm not sure that there's a huge difference between a single patch or multiple patches for each arch unless there's some functionality dependent on being able to read the actual value of a pin configured as a GPIO output. Did I miss something in this thread that does actually require that ability? It seems a pretty obscure thing in the normal case to drive an output without confidence that it will succeed. Regards, Eric