From: Yen Lin <yelin@nvidia.com>
To: u-boot@lists.denx.de
Subject: [U-Boot] [PATCH 09/14] tegra: Add warmboot implementation
Date: Fri, 13 Jan 2012 16:04:11 -0800 [thread overview]
Message-ID: <1326499451.16046.116.camel@yelin-desktop> (raw)
In-Reply-To: <4F10B978.2000200@nvidia.com>
On Fri, 2012-01-13 at 15:08 -0800, Stephen Warren wrote:
> On 01/13/2012 04:05 PM, Simon Glass wrote:
> > On Fri, Jan 13, 2012 at 2:04 PM, Yen Lin <yelin@nvidia.com> wrote:
> >> On Fri, 2012-01-13 at 11:34 -0800, Simon Glass wrote:
> >>> On Tue, Jan 10, 2012 at 10:30 AM, Stephen Warren <swarren@nvidia.com> wrote:
> >>>> On 12/26/2011 12:33 PM, Simon Glass wrote:
> ...
> >>> But there a few questions here. Firstly it seems that it saves some
> >>> memory speed info to scratch2 but never restores it. Then it restores
> >>> CPU speed from scratch3 but I can't see where it saves it. Does Yen
> >>> have any comments on that? Apparently it works because we have been
> >>> using it, but... If it is saving things that are never restored I
> >>> could dump that and reduce the code size.
> >>>
> >>
> >> U-boot code saves sdram parameters to scratch2, scratch4, and scratch 24
> >> registers, so when system resumes, bootrom can restore sdram parameters
> >> from these registers.
> >>
> >> The scratch3 register content was saved by kernel before suspend, and is
> >> used by the warmboot code to restore PLLX settings.
> >
> > Thanks for the info.
> >
> > On resume I do not see it using scratch2, 4 or 24 within U-Boot. Are
> > those used in the kernel?
>
> The Tegra boot ROM (which contains the power-on code for the AVP) is
> what interprets these, according to Yen above.
>
> One question for Yen: Why doesn't the boot ROM read the SDRAM parameters
> from the BCT like it does during a cold boot? Perhaps there's some
> interaction with clock settings, so the boot ROM needs to know the
> clock/voltage/... state the kernel was in when suspending, rather than
> just using the "usual" cold boot settings?
>
This is to reduce latency. During resume, Bootrom will not read BCT
(from SPI or EMMC) to set SDRAM parameters. Instead, it reads directly
from those scratch registers to set SDRAM.
> > I should add something to document this so the kernel people can match
> > up when that side of it goes up stream.
>
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next prev parent reply other threads:[~2012-01-14 0:04 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-26 19:32 [U-Boot] [PATCH 0/14] tegra: warmboot (suspend / resume) support Simon Glass
2011-12-26 19:32 ` [U-Boot] [PATCH 01/14] Add AES crypto library Simon Glass
2012-01-08 5:49 ` Mike Frysinger
2012-01-08 8:57 ` Marek Vasut
2012-01-08 9:09 ` Mike Frysinger
2012-01-08 10:40 ` Marek Vasut
2012-01-08 16:35 ` Simon Glass
2011-12-26 19:32 ` [U-Boot] [PATCH 02/14] tegra: Move ap20.h header into arch location Simon Glass
2011-12-26 19:32 ` [U-Boot] [PATCH 03/14] tegra: Add crypto library for warmboot code Simon Glass
2012-01-08 5:51 ` Mike Frysinger
2012-01-08 16:42 ` Simon Glass
2011-12-26 19:32 ` [U-Boot] [PATCH 04/14] tegra: Add flow, gp_padctl, fuse, sdram headers Simon Glass
2011-12-26 19:32 ` [U-Boot] [PATCH 05/14] tegra: Add tegra_get_chip_type() to detect SKU Simon Glass
2012-01-09 23:24 ` Stephen Warren
2012-01-12 19:35 ` Simon Glass
2012-01-12 19:48 ` Stephen Warren
2012-01-13 21:06 ` Simon Glass
2011-12-26 19:32 ` [U-Boot] [PATCH 06/14] tegra: Add EMC support for optimal memory timings Simon Glass
2012-01-09 23:38 ` Stephen Warren
2012-01-12 20:43 ` Simon Glass
2012-01-13 17:47 ` Simon Glass
2011-12-26 19:33 ` [U-Boot] [PATCH 07/14] tegra: Add PMU to manage power supplies Simon Glass
2012-01-10 17:56 ` Stephen Warren
2012-01-12 23:17 ` Simon Glass
2012-01-12 23:43 ` Stephen Warren
2012-01-12 23:55 ` Simon Glass
2011-12-26 19:33 ` [U-Boot] [PATCH 08/14] tegra: Set up PMU for Nvidia boards Simon Glass
2012-01-10 18:02 ` Stephen Warren
2012-01-12 23:42 ` Simon Glass
2011-12-26 19:33 ` [U-Boot] [PATCH 09/14] tegra: Add warmboot implementation Simon Glass
2012-01-10 18:30 ` Stephen Warren
2012-01-13 19:34 ` Simon Glass
2012-01-13 22:04 ` Yen Lin
2012-01-13 23:05 ` Simon Glass
2012-01-13 23:08 ` Stephen Warren
2012-01-14 0:04 ` Yen Lin [this message]
2011-12-26 19:33 ` [U-Boot] [PATCH 10/14] tegra: Setup PMC scratch info from ap20 setup Simon Glass
2011-12-26 19:33 ` [U-Boot] [PATCH 11/14] tegra: Set up warmboot code on Nvidia boards Simon Glass
2011-12-26 19:33 ` [U-Boot] [PATCH 12/14] tegra: Set vdd_core and vdd_cpu to high Simon Glass
2012-01-10 18:40 ` Stephen Warren
2012-01-13 17:55 ` Simon Glass
2011-12-26 19:33 ` [U-Boot] [PATCH 13/14] tegra: Add EMC settings for Seaboard, Harmony Simon Glass
2012-01-10 18:46 ` Stephen Warren
2012-01-12 23:05 ` Simon Glass
2012-01-12 23:42 ` Stephen Warren
2012-01-12 23:54 ` Simon Glass
2012-01-13 0:01 ` Stephen Warren
2012-01-13 0:05 ` Simon Glass
2012-01-13 0:10 ` Stephen Warren
2012-01-13 0:18 ` Simon Glass
2011-12-26 19:33 ` [U-Boot] [PATCH 14/14] tegra: Enable LP0 on Seaboard Simon Glass
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