From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfgang Denk Date: Tue, 23 Mar 2004 22:38:04 +0100 Subject: [U-Boot-Users] Patch: Support for PQ27e (8247/48/71/72) chips and MPC8272ADS board In-Reply-To: Your message of "Tue, 16 Mar 2004 08:37:33 CST." <761C62B8-7757-11D8-A4C6-000393DBC2E8@motorola.com> Message-ID: <20040323213809.2FAB4C0655@atlas.denx.de> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de In message <761C62B8-7757-11D8-A4C6-000393DBC2E8@motorola.com> you wrote: > > I agree with only enabling ports that will be used. I guess I would > expect the port to be used in Linux. I'm working on an updated 2.6 SCC > uart driver and realized that I needed to enable the 2nd port in BCSR. > I had expected that u-boot would have already handled it. The philosophy is to enable and/or initialize only those devices which are actually used by U-Boot itself. Even the network interfaces get initialized only at the moment when you issue the first command to access the network. On the other hand a Linux device driver should assume it finds the device in an unknown random (*) state, it should perform all initialization it needs itself, and it should deinitialize the device (if the driver should get unloaded) into an idle state. (*) "random" is not completely random, of course - it still assumes that the device is well-behaving, i. e. that interrupts are disabled etc. Best regards, Wolfgang Denk -- Software Engineering: Embedded and Realtime Systems, Embedded Linux Phone: (+49)-8142-4596-87 Fax: (+49)-8142-4596-88 Email: wd at denx.de "When anyone says `theoretically,' they really mean `not really.'" - David Parnas