From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9BC09C433EF for ; Mon, 7 Feb 2022 08:23:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233017AbiBGIVY (ORCPT ); Mon, 7 Feb 2022 03:21:24 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52538 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239163AbiBGIN6 (ORCPT ); Mon, 7 Feb 2022 03:13:58 -0500 X-Greylist: delayed 564 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Mon, 07 Feb 2022 00:13:57 PST Received: from muru.com (muru.com [72.249.23.125]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 9E445C043181 for ; Mon, 7 Feb 2022 00:13:57 -0800 (PST) Received: from localhost (localhost [127.0.0.1]) by muru.com (Postfix) with ESMTPS id 8E5DF80E1; Mon, 7 Feb 2022 08:04:10 +0000 (UTC) Date: Mon, 7 Feb 2022 10:04:31 +0200 From: Tony Lindgren To: Romain Naour Cc: linux-omap@vger.kernel.org Subject: Re: AM5749: tty serial 8250 omap driver crash Message-ID: References: <2c80fd8a-2935-9a6d-43fd-f95fa53c93d2@smile.fr> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2c80fd8a-2935-9a6d-43fd-f95fa53c93d2@smile.fr> Precedence: bulk List-ID: X-Mailing-List: linux-omap@vger.kernel.org Hi, * Romain Naour [220204 13:39]: > It seems that the driver fail to read the UART_LCR register from > omap8250_set_mctrl(): > > "lcr = serial_in(up, UART_LCR);" > > PC is at mem_serial_in+0x2c/0x30 > LR is at omap8250_set_mctrl+0x48/0xb0 > > The problem only occurs with a -rt kernel, I tried with several kernel version: > 5.10-rt, 5.15-rt and 5.17-rt. > > I'm not able to reproduce the issue with a standard kernel. Interesting, what's the exception you get with the -rt kernel? Is it an unhandled external abort or something else? > While looking at the git history, I noticed this commit [3] about "flakey idling > of uarts and stop using swsup_sidle_act". > > So I removed the SYSC_QUIRK for uart IP revision 0x50411e03 and it fixed my issue. Hmm. > Is the SYSC_QUIRK for omap4 still needed ? Is it safe to remove it ? > It seems this issue was introduced while dropping the legacy platform data > (between 4.19 and 5.4 kernels). AFAIK it's still needed, but maybe we can disable it for am57xx though. Regards, Tony