Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752966AbdC1MeP (ORCPT ); Tue, 28 Mar 2017 08:34:15 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:58988 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752931AbdC1MeN (ORCPT ); Tue, 28 Mar 2017 08:34:13 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nicolas Ferre , Alexandre Belloni Subject: [PATCH 4.4 45/76] ARM: at91: pm: cpu_idle: switch DDR to power-down mode Date: Tue, 28 Mar 2017 14:30:42 +0200 Message-Id: <20170328122601.791912192@linuxfoundation.org> X-Mailer: git-send-email 2.12.1 In-Reply-To: <20170328122559.966310440@linuxfoundation.org> References: <20170328122559.966310440@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2398 Lines: 68 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Nicolas Ferre commit 60b89f1928af80b546b5c3fd8714a62f6f4b8844 upstream. On some DDR controllers, compatible with the sama5d3 one, the sequence to enter/exit/re-enter the self-refresh mode adds more constrains than what is currently written in the at91_idle driver. An actual access to the DDR chip is needed between exit and re-enter of this mode which is somehow difficult to implement. This sequence can completely hang the SoC. It is particularly experienced on parts which embed a L2 cache if the code run between IDLE calls fits in it... Moreover, as the intention is to enter and exit pretty rapidly from IDLE, the power-down mode is a good candidate. So now we use power-down instead of self-refresh. As we can simplify the code for sama5d3 compatible DDR controllers, we instantiate a new sama5d3_ddr_standby() function. Signed-off-by: Nicolas Ferre Fixes: 017b5522d5e3 ("ARM: at91: Add new binding for sama5d3-ddramc") Signed-off-by: Alexandre Belloni Signed-off-by: Greg Kroah-Hartman --- arch/arm/mach-at91/pm.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) --- a/arch/arm/mach-at91/pm.c +++ b/arch/arm/mach-at91/pm.c @@ -286,6 +286,22 @@ static void at91_ddr_standby(void) at91_ramc_write(1, AT91_DDRSDRC_LPR, saved_lpr1); } +static void sama5d3_ddr_standby(void) +{ + u32 lpr0; + u32 saved_lpr0; + + saved_lpr0 = at91_ramc_read(0, AT91_DDRSDRC_LPR); + lpr0 = saved_lpr0 & ~AT91_DDRSDRC_LPCB; + lpr0 |= AT91_DDRSDRC_LPCB_POWER_DOWN; + + at91_ramc_write(0, AT91_DDRSDRC_LPR, lpr0); + + cpu_do_idle(); + + at91_ramc_write(0, AT91_DDRSDRC_LPR, saved_lpr0); +} + /* We manage both DDRAM/SDRAM controllers, we need more than one value to * remember. */ @@ -320,7 +336,7 @@ static const struct of_device_id const r { .compatible = "atmel,at91rm9200-sdramc", .data = at91rm9200_standby }, { .compatible = "atmel,at91sam9260-sdramc", .data = at91sam9_sdram_standby }, { .compatible = "atmel,at91sam9g45-ddramc", .data = at91_ddr_standby }, - { .compatible = "atmel,sama5d3-ddramc", .data = at91_ddr_standby }, + { .compatible = "atmel,sama5d3-ddramc", .data = sama5d3_ddr_standby }, { /*sentinel*/ } };