From mboxrd@z Thu Jan 1 00:00:00 1970 From: Santosh Shilimkar Subject: Re: [PATCH, RFC 0/8] ARM: AM43 (OMAP2+) boot support Date: Tue, 19 Feb 2013 15:39:32 +0530 Message-ID: <51234F5C.6050500@ti.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-doc-owner@vger.kernel.org To: Afzal Mohammed Cc: linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, devicetree-discuss@lists.ozlabs.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Russell King , Tony Lindgren , Marc Zyngier , Nicolas Pitre , Will Deacon , Linus Walleij , Rob Herring , Grant Likely , Rob Landley , Sekhar Nori , Syed Mohammed Khasim List-Id: linux-omap@vger.kernel.org On Monday 18 February 2013 05:05 PM, Afzal Mohammed wrote: > (Resending, since it seems, LAKML doesn't accept patches with subject > prefix only as "RFC", but requires "PATCH" prefix also) > > Hi, > > This series adds minimal support to boot Linux on platforms having > AM43 based SoC's. > > This is being sent as an RFC to seek opinion about modification in > twd to register percpu local timer clock event for scheduler tick in > the case of one core SMP. > > AM43 SoC's are based on ARM Cortex-A9. It is an ARM Cortex-A9 SMP > configuration with one core (not uniprocessor configuration). AM43 is > similar to AM335x in it's peripheral capabilities, with many of the > peripheral register mapping's similar like that of uart. > After looking at the specs, you don't need the SMP mode since ACP isn't being used. > AM43 is in pre-silicon stage and currently there are no public > documents. > > This series has been tested on a pre-silicon platform that emulates > AM43 SoC, changes proposed here are minimal - to get it booting. > Kernel was directly run without the help of bootloader - Images were > directly loaded onto a pre-initialized RAM and ARM registers updated > as required for booting. > > Changes have been made over linux-next (next-20130213) with three "OF" > related reverts (which otherwise causes problem in other platforms > also) and compiled with omap2plus_defconfig. Multiplatform option was > enabled, while most of CONFIG options were deselected for a faster > boot. Beagle bone boots as earlier with these changes. > > An interesting observation is that it may be possible to boot this > platform to console without any platform specific modification to > proper Kernel (by that I mean excluding DT sources) using Arnd's, > > "[PATCH,RFC] default machine descriptor for multiplatform", > > along with a "CLOCKSOURCE_OF_DECLARE" for smp twd. > TWD use for AM437x is also limited because these times stops in low power sates and there you will need broad-cast mechanism which again more of SMP machine feature. So I suggest to use the wakeup timer(GPT1) clock-event instead of local timer for the mentioned reason. Regards, Santosh