From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jSz88-0006zn-BG for barebox@lists.infradead.org; Mon, 27 Apr 2020 08:28:48 +0000 References: <20200427071351.467859-1-ahmad@a3f.at> <20200427080727.GO5877@pengutronix.de> From: Ahmad Fatoum Message-ID: Date: Mon, 27 Apr 2020 10:28:42 +0200 MIME-Version: 1.0 In-Reply-To: <20200427080727.GO5877@pengutronix.de> Content-Language: en-US List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: [PATCH 1/3] ARM: i.MX: boot: correctly handle SRC_SBMR1 override via SRC_GPR9 To: Sascha Hauer , Ahmad Fatoum Cc: barebox@lists.infradead.org Hello, On 4/27/20 10:07 AM, Sascha Hauer wrote: > On Mon, Apr 27, 2020 at 09:13:49AM +0200, Ahmad Fatoum wrote: >> `mw 0x20d8040 0x08000030; mw 0x20d8044 0x10000000; reset` issued on an >> i.MX6Q forces boot from the ecspi1. This is because the BootROM reads >> the boot mode out of SRC_GPR9 instead of SRC_SBMR1 whenever SRC_GPR10 >> has its 28th bit set. > > Is this documented somewhere? The reference Manual marks SRC_GPR9 and > SRC_GPR10 as > > | This register is used by the ROM code and should not be used > | by application software. Not documented anywhere, except for U-Boot's bmode command and boot source determination code: https://github.com/trini/u-boot/blob/v2020.04/arch/arm/mach-imx/mx6/soc.c#L560 https://github.com/trini/u-boot/blob/v2020.04/arch/arm/mach-imx/init.c#L104 > And why do you depend on this behaviour? It's a useful debugging aid, when strap pins aren't easily accessible, because then your only other option is then to fuse to affect the boot (or short your SPI I/O pins). I am preparing code to provide a generic reboot mode functionality in barebox. This would among others cover the functionality of the U-Boot bmode command and these patches here are prerequisites, so the boot source detection remains accurate. Cheers > > Sascha > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox