From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e3.ny.us.ibm.com (e3.ny.us.ibm.com [32.97.182.143]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e3.ny.us.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTP id 4A186DDE29 for ; Fri, 12 Oct 2007 21:52:06 +1000 (EST) Received: from d01relay02.pok.ibm.com (d01relay02.pok.ibm.com [9.56.227.234]) by e3.ny.us.ibm.com (8.13.8/8.13.8) with ESMTP id l9CBpvFk023221 for ; Fri, 12 Oct 2007 07:51:57 -0400 Received: from d01av04.pok.ibm.com (d01av04.pok.ibm.com [9.56.224.64]) by d01relay02.pok.ibm.com (8.13.8/8.13.8/NCO v8.5) with ESMTP id l9CBpve0119378 for ; Fri, 12 Oct 2007 07:51:57 -0400 Received: from d01av04.pok.ibm.com (loopback [127.0.0.1]) by d01av04.pok.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id l9CBplsd003913 for ; Fri, 12 Oct 2007 07:51:47 -0400 Subject: Re: [PATCH] PowerPC: Fix find_legacy_serial_ports on OPB. From: Josh Boyer To: David Gibson In-Reply-To: <20071012023149.GA21056@localhost.localdomain> References: <20071011152609.GA10320@ru.mvista.com> <200710111750.41852.arnd@arndb.de> <1192118028.5534.123.camel@localhost.localdomain> <470E5CBC.9040604@ru.mvista.com> <1192127513.5534.127.camel@localhost.localdomain> <20071012023149.GA21056@localhost.localdomain> Content-Type: text/plain Date: Fri, 12 Oct 2007 06:49:59 -0500 Message-Id: <1192189799.3061.24.camel@localhost.localdomain> Mime-Version: 1.0 Cc: linuxppc-dev@ozlabs.org, Arnd Bergmann List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, 2007-10-12 at 12:31 +1000, David Gibson wrote: > On Thu, Oct 11, 2007 at 01:31:53PM -0500, Josh Boyer wrote: > > On Thu, 2007-10-11 at 21:26 +0400, Valentine Barshak wrote: > > > Josh Boyer wrote: > > > > On Thu, 2007-10-11 at 17:50 +0200, Arnd Bergmann wrote: > > > >> On Thursday 11 October 2007, Valentine Barshak wrote: > > > >>> Currently find_legacy_serial_ports() can find no serial ports on the OPB. > > > >>> Thus no legacy boot console can be initialized. Just the early udbg console > > > >>> works, which is initialized with udbg_init_44x_as1() on the UART's physical > > > >>> address specified in kernel config. This happens because we look for ns16750 > > > >>> and higher serial devices only and expect opb node to have a device type > > > >>> property. This patch makes it look for ns16550 compatible devices and use > > > >>> of_device_is_compatible() for opb instead of checking device type. > > > >>> Lack of legacy serial ports found causes problems for KGDB over serial. > > > >>> > > > >>> Signed-off-by: Valentine Barshak > > > >> The patch would make sense if we were only dealing with flattened device > > > >> tree systems at this point. Unfortunately, IBM is shipping hardware that > > > >> encodes the serial port in exactly the way that find_legacy_serial_ports > > > >> is looking for (parent->type == "opb", compatible = "ns16750" "ns16550" > > > >> "ns16450" i8250"). > > > >> > > > >> Changing the search for ns16750 to ns16550 should be fine, but unnecessary > > > >> because AFAIK, all OPB serial imlpementations are actually ns16750 and > > > >> should have that in the device tree as well. > > > >> > > > >> For the device type of the bus, please check for both compatible and > > > >> type, so that it still works on machines that are missing the compatible > > > >> property. > > > > > > > > Wait, no. We already had this discussion months ago when David was > > > > working on the original Ebony port. It was declared that legacy_serial > > > > is not how serial should be done on 4xx and the serial_of driver was > > > > supposed to be used instead. > > > > > > > > Have we changed our stance on that? If not, then perhaps KGDB should be > > > > fixed to work with serial_of. > > > > > > Actually I don't see any reason not to use legacy_serial stuff for early > > > console. We could split the kernel configured very early debug output, > > > which uses PPC_EARLY_DEBUG_44x_PHYSLOW/PHYSHIGH (since it's really > > > dangerous) and early console things by using legacy serial. We could use > > > early boot console without PPC_EARLY_DEBUG_44x. > > > > That was exactly my thinking when this first came up. I'd like to hear > > David's opinion on it. > > Yeah, I think I misinterpreted BenH way back when. This looks ok, and > means serial will be initialized earlier than of_serial, which would > be nice. Great. It seems Paul pulled it into his tree already as well, which suits me just fine. josh