From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e34.co.us.ibm.com (e34.co.us.ibm.com [32.97.110.152]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e34.co.us.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTP id 0F4DFDE09B for ; Fri, 12 Oct 2007 04:35:32 +1000 (EST) Received: from d03relay04.boulder.ibm.com (d03relay04.boulder.ibm.com [9.17.195.106]) by e34.co.us.ibm.com (8.13.8/8.13.8) with ESMTP id l9BIZQjv011921 for ; Thu, 11 Oct 2007 14:35:26 -0400 Received: from d03av04.boulder.ibm.com (d03av04.boulder.ibm.com [9.17.195.170]) by d03relay04.boulder.ibm.com (8.13.8/8.13.8/NCO v8.5) with ESMTP id l9BIZQb7345742 for ; Thu, 11 Oct 2007 12:35:26 -0600 Received: from d03av04.boulder.ibm.com (loopback [127.0.0.1]) by d03av04.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id l9BIZP7V021568 for ; Thu, 11 Oct 2007 12:35:26 -0600 Subject: Re: [PATCH] PowerPC: Fix find_legacy_serial_ports on OPB. From: Josh Boyer To: Valentine Barshak In-Reply-To: <470E5CBC.9040604@ru.mvista.com> References: <20071011152609.GA10320@ru.mvista.com> <200710111750.41852.arnd@arndb.de> <1192118028.5534.123.camel@localhost.localdomain> <470E5CBC.9040604@ru.mvista.com> Content-Type: text/plain Date: Thu, 11 Oct 2007 13:31:53 -0500 Message-Id: <1192127513.5534.127.camel@localhost.localdomain> Mime-Version: 1.0 Cc: linuxppc-dev@ozlabs.org, Arnd Bergmann , david@gibson.dropbear.id.au List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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. josh