From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:58388 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752555AbeDJJHs (ORCPT ); Tue, 10 Apr 2018 05:07:48 -0400 Subject: Patch "powerpc/[booke|4xx]: Don't clobber TCR[WP] when setting TCR[DIE]" has been added to the 4.4-stable tree To: ivan@de.ibm.com, alexander.levin@microsoft.com, gregkh@linuxfoundation.org, mpe@ellerman.id.au Cc: , From: Date: Tue, 10 Apr 2018 11:05:36 +0200 Message-ID: <1523351136176140@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled powerpc/[booke|4xx]: Don't clobber TCR[WP] when setting TCR[DIE] to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: powerpc-don-t-clobber-tcr-when-setting-tcr.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From foo@baz Tue Apr 10 10:31:53 CEST 2018 From: Ivan Mikhaylov Date: Fri, 19 May 2017 18:47:05 +0300 Subject: powerpc/[booke|4xx]: Don't clobber TCR[WP] when setting TCR[DIE] From: Ivan Mikhaylov [ Upstream commit 6e2f03e292ef46eed2b31b0a344a91d514f9cd81 ] Prevent a kernel panic caused by unintentionally clearing TCR watchdog bits. At this point in the kernel boot, the watchdog may have already been enabled by u-boot. The original code's attempt to write to the TCR register results in an inadvertent clearing of the watchdog configuration bits, causing the 476 to reset. Signed-off-by: Ivan Mikhaylov Signed-off-by: Michael Ellerman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/kernel/time.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -686,12 +686,20 @@ static int __init get_freq(char *name, i static void start_cpu_decrementer(void) { #if defined(CONFIG_BOOKE) || defined(CONFIG_40x) + unsigned int tcr; + /* Clear any pending timer interrupts */ mtspr(SPRN_TSR, TSR_ENW | TSR_WIS | TSR_DIS | TSR_FIS); - /* Enable decrementer interrupt */ - mtspr(SPRN_TCR, TCR_DIE); -#endif /* defined(CONFIG_BOOKE) || defined(CONFIG_40x) */ + tcr = mfspr(SPRN_TCR); + /* + * The watchdog may have already been enabled by u-boot. So leave + * TRC[WP] (Watchdog Period) alone. + */ + tcr &= TCR_WP_MASK; /* Clear all bits except for TCR[WP] */ + tcr |= TCR_DIE; /* Enable decrementer */ + mtspr(SPRN_TCR, tcr); +#endif } void __init generic_calibrate_decr(void) Patches currently in stable-queue which might be from ivan@de.ibm.com are queue-4.4/powerpc-don-t-clobber-tcr-when-setting-tcr.patch