From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Frysinger Date: Thu, 17 May 2012 22:48:18 -0400 Subject: [U-Boot] [RFC] Make i2c probe opt-outable? In-Reply-To: <20120517184345.GA23562@bill-the-cat> References: <20120517184345.GA23562@bill-the-cat> Message-ID: <201205172248.20143.vapier@gentoo.org> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On Thursday 17 May 2012 14:43:45 Tom Rini wrote: > I'd like to propose making 'i2c probe' be a command that is > opt-out'able. In the Linux Kernel the notion of probing for devices was > abandoned a while ago due to, in short, devices misbehaving when > randomly poked at. Over in omap24xx_i2c land we changed our probe > method a while ago from an attempted read to an attempted write as some > i2c devices would NAK the read. But now with the am33xx SoM family we > have a new issue which is that attempting to write to an address doesn't > immediately issue a NAK so probe sees all addresses as valid and in turn > leaves the bus upset. I've worked around this for now by making > i2c_probe use the read method instead, only on am33xx (so most devices > would be spotted, but the ones that caused the initial change would not > show up). But a possibly better solution is to just make the i2c probe > command not implemented for am33xx (as you don't have to run i2c probe > to try and use your device). i've always seen the "i2c probe" command as a debugging tool, not something that you need to do to make things work. so along those lines, isn't it already optional ? if you don't like it, don't run it :). -mike -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 836 bytes Desc: This is a digitally signed message part. URL: