From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marek Vasut Date: Thu, 2 Oct 2014 13:23:30 +0200 Subject: [U-Boot] [RFC PATCH 4/4 v3] mtd: sf: Add CONFIG_SPI_N25Q256A_RESET for software-reset In-Reply-To: <20141002084052.GA10339@pollux.denx.de> References: <1412176391-24475-1-git-send-email-sr@denx.de> <201410020447.23583.marex@denx.de> <20141002084052.GA10339@pollux.denx.de> Message-ID: <201410021323.30310.marex@denx.de> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On Thursday, October 02, 2014 at 10:40:52 AM, Pavel Machek wrote: > On Thu 2014-10-02 04:47:23, Marek Vasut wrote: > > On Wednesday, October 01, 2014 at 09:04:48 PM, Jagan Teki wrote: > > > On 2 October 2014 00:27, Stefan Roese wrote: > > > > On 01.10.2014 20:25, Marek Vasut wrote: > > > >> On Wednesday, October 01, 2014 at 05:13:11 PM, Stefan Roese wrote: > > > >>> This is needed for the SoCFPGA booting from SPI NOR flash > > > >>> e.g. (N25Q256A). With these changes, the SoCrates can boot and > > > >>> re-boot (reset) from SPI NOR flash without any problems. > > > >> > > > >> Seems like your SPI NOR reset logic is buggy. Does any of [1] apply > > > >> to your > > > >> board please? > > > >> > > > >> [1] > > > >> http://www.rocketboards.org/foswiki/Documentation/SocBoardQspiBoot > > > > > > > > Yes. This seems to be that case. But I can't change it right now. So > > > > this "solution" with the soft-reset is better than nothing. > > > > > > If this is some think that must require, any possibility to this > > > resetting prior to u-boot? > > > like preloader or in first stage boot loader or something. > > > > You do understand, that this is a hardware bug on one particular board, > > right ? This can _not_ be reliably solved in software, not ever. I keep > > seeing people implementing one such workaround after the other in > > linux-mtd list, but sooner or later, they discover that their workaround > > is not reliable. Without proper reset logic in place, a system simply > > cannot reliably reboot, since it has no way to put all the hardware into > > defined state. > > Well, if you have >16M flash and if you need bootrom to work with it. > > AFAICT, as long as you avoid using SPI from bootrom (socrates will happily > run from SD card, for example), reliable operation should be possible. And > you can still use SPI from Linux and u-boot... SD has the same problem if you don't have proper reset logic for it ;-) Best regards, Marek Vasut