From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Roese Subject: AM335x board with disabled RTC crashes Date: Wed, 20 Nov 2013 15:18:51 +0100 Message-ID: <528CC4CB.4000609@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from mo-p05-ob.rzone.de ([81.169.146.181]:9672 "EHLO mo-p05-ob.rzone.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751375Ab3KTOS6 (ORCPT ); Wed, 20 Nov 2013 09:18:58 -0500 Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: linux-omap Cc: Tony Lindgren Hi! I'm currently working on a custom AM335x based board, where the SoC RTC is disabled. As described in this page in the "RTC feature disabled" column: http://processors.wiki.ti.com/index.php/AM335x_Schematic_Checklist#RTC On this board the registers of the RTC are not accessible. But the OMAP hwmod code tries to read the sysc register unconditionally from the RTC. And this leads to this crash (using v3.12): ... [ 0.179491] CPU: Testing write buffer coherency: ok [ 0.187702] Setting up static identity map for 0xc04dfa90 - 0xc04dfb00 [ 0.204665] devtmpfs: initialized [ 0.219513] VFP support v0.3: implementor 41 architecture 3 part 30 variant c rev 3 [ 0.237462] *** _update_sysc_cache (263): name=emif [ 0.246247] omap_hwmod: debugss: _wait_target_disable failed [ 0.252290] *** _update_sysc_cache (263): name=uart1 [ 0.257668] *** _update_sysc_cache (263): name=rtc [ 0.262885] Unhandled fault: external abort on non-linefetch (0x1028) at 0xf9e3e078 [ 0.270893] Internal error: : 1028 [#1] ARM [ 0.275302] Modules linked in: [ 0.278572] CPU: 0 PID: 1 Comm: swapper Not tainted 3.12.0-dirty #21 [ 0.285222] task: c7047340 ti: c7048000 task.ti: c7048000 [ 0.290909] PC is at _update_sysc_cache+0x44/0xb0 [ 0.295861] LR is at _update_sysc_cache+0x1c/0xb0 ... Disabling the RTC in the DT doesn't help (of course). So what's the recommended way to disable this hwmod access to the RTC registers? Thanks, Stefan