Dear Wolfgang Denk, > -----Original Message----- > From: u-boot-boun...@lists.denx.de [mailto:u-boot- > boun...@lists.denx.de] On Behalf Of V, Aneesh > Sent: Monday, September 27, 2010 12:03 PM > To: Wolfgang Denk; Nishanth Menon > Cc: u-boot@lists.denx.de; Steve Sakoman > Subject: Re: [U-Boot] [PATCH] ARMV7: OMAP4: Calculate SDRAM size > > Dear Wolfgang Denk, > > > -----Original Message----- > > From: Wolfgang Denk [mailto:w...@denx.de] > > Sent: Sunday, September 26, 2010 8:07 PM > > To: Nishanth Menon > > Cc: V, Aneesh; u-boot@lists.denx.de; Steve Sakoman > > Subject: Re: [U-Boot] [PATCH] ARMV7: OMAP4: Calculate SDRAM size > > > > Dear Nishanth Menon, > > > > In message <4c9f3e4f.3040...@gmail.com> you wrote: > > > > > > > I think you are referring to SDRAM initialization. Yes, it is > > assumed > > > > that SDRAM initialization(at least the DMM part of it) is done > > before > > > > the call to sdram_size(). The right location for this seems > > > > to be the initial part of sdram_init(). > > > > > > thanks for the clarification.. NOR boot is usually going to have > > initial > > > part in XIP -> we'd traditionally relocate to SDRAM before the > > call to > > > sdram_size() happens. > > > > Yes, this was the way how many ARM boards id, and this is what I'm > > trying to explain: this is WRONG. > > > > SDRAM configuration must be done while still running from NOR, i. > e. > > before relocation. Only then free reconfiguration, auto-sizing > etc. > > is > > possible. > > We shall rework the patch to do SDRAM size calculation as part of > 'lowlevel_init' that is called before relocation. I hope that should > solve the problem.
I realize that gd will not be setup at this point of time. So, I would propose keeping the same patch. sdram_size() can be called at any point of time as SDRAM is initialized by the time u-boot starts. We can do whatever extra needed to support the new relocation scheme once those patches are upstream. > > Please note that we are always running from SDRAM because none of > the OMAP4 boards so far have any XIP device. > > Regarding true run-time detection of SDRAM size and configuration: > We do not support it today. However, LPDDR2 supports Mode Registers > that have size info and our memory controller can read it. This > coupled with the base AC timings specified by the LPDDR2 spec > creates the possibility of doing a truly run-time detection and > configuration of SDRAM that works for all boards. I was indeed > thinking of trying it out sometime. Please note that the base AC > timing values may not be optimal for all memory parts. > Best regards, Aneesh _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
