Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933508AbbLBRG6 (ORCPT ); Wed, 2 Dec 2015 12:06:58 -0500 Received: from mail-wm0-f51.google.com ([74.125.82.51]:34306 "EHLO mail-wm0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933107AbbLBRGz (ORCPT ); Wed, 2 Dec 2015 12:06:55 -0500 From: Maxime Coquelin To: Arnd Bergmann , olof@lixom.net, khilman@kernel.org, linux-arm-kernel@lists.infradead.org Cc: devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Daniel Thompson , Kamil Lulko , afaerber@suse.de Subject: [PATCH] ARM: dts: stm32f429: Boost perfs by remapping SDRAM Bank 1 to 0x0 Date: Wed, 2 Dec 2015 18:06:52 +0100 Message-Id: <1449076012-19519-1-git-send-email-mcoquelin.stm32@gmail.com> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2200 Lines: 67 STM32F429 allows to remap FMC SDRAM Bank 1 from 0xc0000000 to 0x0, by writing 0x4 to SYSCFG_MEMRMP register. As mentionned in the reference manual (see chapter 9.3.1), the performance gain is really interresting: "In remap mode at address 0x0000 0000, the CPU can access the external memory via ICode bus instead of System bus which boosts up the performance." These are the dhrystone results with and without the remap enabled: Default (SDRAM in 0xc0000000): --------------------------------- Microseconds for one run through Dhrystone: 31.8 Dhrystones per Second: 31416.9 Remap (SDRAM in 0x0000000): ----------------------------- Microseconds for one run through Dhrystone: 20.6 Dhrystones per Second: 48520.1 This patch first change the SDRAM start address to 0x0 for STM32429i-EVAL board, and also set the dma-range property as the other masters than the M4 CPU still see SDRAM in 0xc0000000. Note that the Discovery board cannot benefit from this feature, since the SDRAM is connected to Bank 2. Signed-off-by: Maxime Coquelin --- arch/arm/boot/dts/stm32429i-eval.dts | 2 +- arch/arm/boot/dts/stm32f429.dtsi | 2 ++ 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/arm/boot/dts/stm32429i-eval.dts b/arch/arm/boot/dts/stm32429i-eval.dts index 6964fc9..a717acb 100644 --- a/arch/arm/boot/dts/stm32429i-eval.dts +++ b/arch/arm/boot/dts/stm32429i-eval.dts @@ -58,7 +58,7 @@ }; memory { - reg = <0xc0000000 0x2000000>; + reg = <0x00000000 0x2000000>; }; aliases { diff --git a/arch/arm/boot/dts/stm32f429.dtsi b/arch/arm/boot/dts/stm32f429.dtsi index eaf7a72..84e5fb3 100644 --- a/arch/arm/boot/dts/stm32f429.dtsi +++ b/arch/arm/boot/dts/stm32f429.dtsi @@ -57,6 +57,8 @@ }; soc { + dma-ranges = <0xc0000000 0x0 0x10000000>; + timer2: timer@40000000 { compatible = "st,stm32-timer"; reg = <0x40000000 0x400>; -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/