Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752858AbaGGUhU (ORCPT ); Mon, 7 Jul 2014 16:37:20 -0400 Received: from mail-lb0-f175.google.com ([209.85.217.175]:63515 "EHLO mail-lb0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751478AbaGGUhS (ORCPT ); Mon, 7 Jul 2014 16:37:18 -0400 MIME-Version: 1.0 In-Reply-To: References: <20140707191430.GA23004@roeck-us.net> <20140707194223.GA29819@roeck-us.net> Date: Mon, 7 Jul 2014 22:37:16 +0200 X-Google-Sender-Auth: rt3uDJXRuWl7MyyhIJYZX1ni48s Message-ID: Subject: Re: 3.15.4 runs *significantly* slower than 3.15.3 on iMX233 CPU From: Geert Uytterhoeven To: Manuel Reimer Cc: "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 7, 2014 at 9:55 PM, Manuel Reimer wrote: > On 07/07/2014 09:42 PM, Guenter Roeck wrote: >>> >>> I tracked the problem down to the following patch: >>> >>> >>> diff --git a/arch/arm/boot/dts/imx23-olinuxino.dts >>> b/arch/arm/boot/dts/imx23-olinuxino.dts >>> index d107c4a..993da2e 100644 >>> --- a/arch/arm/boot/dts/imx23-olinuxino.dts >>> +++ b/arch/arm/boot/dts/imx23-olinuxino.dts >>> @@ -64,7 +64,14 @@ >>> compatible = "fsl,imx23-spi"; >>> pinctrl-names = "default"; >>> pinctrl-0 = <&spi2_pins_a>; >>> + clock-frequency = <1000000>; >> >> >> If I understand the code correctly, that means you reduce the access speed >> for SPI flashes from 160 MHz down to 1 MHz. >> >> If so, and if your system loads anything from a SPI flash, I would not be >> too >> surprised that your system is now a bit on the slow side. > > > The iMX233 has two separate SPI connections. The first one is used to > connect to the SD card where the system boots from and the second one is the > one I plan to use. The idea was to only set clock frequency for the SPI bus, > I want to use to connect to external devices. The "SD SPI" has to run with > "full speed". So where is the mistake... drivers/spi/spi-mxs.c:mxs_spi_probe() ret = of_property_read_u32(np, "clock-frequency", &clk_freq); if (ret) clk_freq = clk_freq_default; ... ret = clk_prepare_enable(ssp->clk); Any chance the clocks are shared, so this changes the rate for the shared clock, affecting both SPI connections? Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- 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/