From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AIpwx4+G2RkdBqWoJoTh4zsjei5V5hGPsXbB73/CzuIpHt/qXO9BfMDV2l44/mlxLQp9DW/jygty ARC-Seal: i=1; a=rsa-sha256; t=1523472107; cv=none; d=google.com; s=arc-20160816; b=jdB/lVLrln6y37obiBJuvoD+0TzWhQvOP6VJ1ZxaUoI/UOQDtHjuCJ3HB5dW28tBeo TPvKr5dTFhBZ8HrDd8k8Mk+0Jay+j2rN1gyyQiopcsS89KThhWulw9diaAX5gN/usKht G/ieBRABttr5XhkfPrpqMcHb+FoXJQASUxhrzSMtwsrCBC0OwoBFub5O1pIQFzwmG7uK k5BmLeddpba7cHwXe0ButZwBQccrUpzFlwDbhzPGnGOP/6DYy9DNoliTQ4Qme5w7uYjJ u3hP+UcFWvjVLolkZOv0exCUcMTPNMmtwP01QrnKEWc6SKs4Fg8EBeO0+3v+MN5IcJXO 0hdQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=tD9aUFMjyshzs5sQPJSiBbeUMMMn2jKQUC/FmvAb0Mc=; b=KPceT6cYF/gkWaYbaRG7uIFQ2JKZQIWzQAB3QN9UFdz4vLzfiN/g+rkRuujfwcFTcB LxkQa/jUtX8ugv+4Wp4hWBawbAkQZggy55ILyQAYiAEhuxFdeawkA5Qo1quU+SZr4VYQ n+xbv30YWmdYgoZ4UONCuCk8nUNmEdij4HTAGPKql0PjvJWDGDCGJfsLn8mQU5ea6ONq WwEbpQFWlKdeVeG/QiSZuv2+otqids/hgwQVFyQpRjdhDEPk1RTCOv0cbr2QKoMUMDCT Yo2z37ccjHaeqO4QYjJw4QsJw7QCWqMYnqDbiuunbzzSyYT2ckMcmQ0vKDHWccbel+j/ D9IA== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ivan Mikhaylov , Michael Ellerman , Sasha Levin Subject: [PATCH 3.18 055/121] powerpc/[booke|4xx]: Dont clobber TCR[WP] when setting TCR[DIE] Date: Wed, 11 Apr 2018 20:35:58 +0200 Message-Id: <20180411183459.654096592@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180411183456.195010921@linuxfoundation.org> References: <20180411183456.195010921@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1597476288698962416?= X-GMAIL-MSGID: =?utf-8?q?1597476288698962416?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ 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 @@ -646,12 +646,20 @@ 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)