From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH 11/12] ARM: dts: add support for Vybrid running on Cortex-M4 Date: Wed, 17 Dec 2014 11:57:06 +0100 Message-ID: <2673866.7fjSqeaHyh@wuerfel> References: <1417565531-4507-1-git-send-email-stefan@agner.ch> <2994970.DCfUQgtmcD@wuerfel> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Stefan Agner Cc: mark.rutland@arm.com, devicetree@vger.kernel.org, linux@arm.linux.org.uk, jason@lakedaemon.net, pawel.moll@arm.com, ijc+devicetree@hellion.org.uk, daniel.lezcano@linaro.org, linux-kernel@vger.kernel.org, robh+dt@kernel.org, kernel@pengutronix.de, u.kleine-koenig@pengutronix.de, olof@lixom.net, galak@codeaurora.org, tglx@linutronix.de, shawn.guo@linaro.org, linux-arm-kernel@lists.infradead.org List-Id: devicetree@vger.kernel.org On Tuesday 16 December 2014 23:19:08 Stefan Agner wrote: > On 2014-12-03 12:03, Arnd Bergmann wrote: > > On Wednesday 03 December 2014 01:12:10 Stefan Agner wrote: > Just started looking in that a bit deeper and some question arose: > Afaik, earlycon need to be supported by the uart driver. The fsl_lpuart, > which is used for Vybrid's uart, does not support earlycon yet. However, > earlyprink already works (see ./arch/arm/include/debug/vf.S). I > understand that earlycon has the advantage of being able to be used on > multiplatform. But earlyprintk is working really early (e.g. before > locating the FDT), and it proved helpful for me when I started working > on that Cortex-M4 stuff. Should earlycon replace earlyprintk completely? earlyprintk will stay around for debugging early boot problems, but with working earlycon support, there should no longer be a reason to enable it by default. > Maybe, on Vybrid, since it would be a good platform for automated !MMU > testing, it would be nice to have earlycon which can be enabled in any > case and would provide output even something blows up quite early... But > I guess I would add earlycon support as part of a new patchset and just > drop earlyprintk here for now. Yes, I think that would be good. > > 64 hash table entries sounds extremely small, doesn't that impact > > performance? If you have 50MB of actual RAM available, I don't think > > you need that. > > Agreed. I copied that from EFM32 which is under much more memory > pressure... Ok. Arnd