From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tom Rini Date: Fri, 18 May 2012 11:43:19 -0700 Subject: [U-Boot] [RFC] Make i2c probe opt-outable? In-Reply-To: <20120518182659.6E492202A22@gemini.denx.de> References: <20120517184345.GA23562@bill-the-cat> <201205172248.20143.vapier@gentoo.org> <4FB674CD.8030502@ti.com> <20120518182659.6E492202A22@gemini.denx.de> Message-ID: <4FB69847.2090703@ti.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 05/18/2012 11:26 AM, Wolfgang Denk wrote: > Dear Tom Rini, > > In message<4FB674CD.8030502@ti.com> you wrote: >> >> But still, the kernel decided i2c probing is dangerous/unreliable, >> maybe we should follow, or at least allow boards to follow? > > The kernel is in a very different situation - it is supposed to run on > perfect hardware. > > In U-Boot, we have to dead with green hardware that is in a completely > unknown state, or with hardware that _might_ be broken in one way or > another. For us tools doing low-level accesses are invaluable - even > if they include the risk to hang a system. Right. I'm not suggesting removing i2c probe, I'm just suggesting making it opt-out'able. For example, on the beaglebone I can make i2c probe work as expected. It's just requring that we toggle the I2C_CON enable bit for some reason in probe, but not when we are actually trying to write to a bad address. I'd like to just #undef CONFIG_CMD_I2C_PROBE for the board and be done with it. Otherwise it lists (nearly) every address which is useless. -- Tom