Re: [PATCH v5 5/8] memory: tegra: Add EMC scaling support code for Tegra210

[Thierry Reding <thierry.reding@gmail.com>]

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On Tue, Mar 10, 2020 at 07:43:12PM +0300, Dmitry Osipenko wrote:
> 10.03.2020 18:20, Thierry Reding пишет:
> > From: Joseph Lo <josephl@nvidia.com>
> > 
> > This is the initial patch for Tegra210 EMC frequency scaling. It has the
> > code to program various aspects of the EMC that are standardized, but it
> > does not yet include the specific programming sequence needed for clock
> > scaling.
> > 
> > The driver is designed to support LPDDR4 SDRAM. Devices that use LPDDR4
> > need to perform training of the RAM before it can be used. Firmware will
> > perform this training during early boot and pass a table of supported
> > frequencies to the kernel via device tree.
> > 
> > For the frequencies above 800 MHz, periodic retraining is needed to
> > compensate for changes in timing. This periodic training will have to be
> > performed until the frequency drops back to or below 800 MHz.
> > 
> > This driver provides helpers used during this runtime retraining that
> > will be used by the sequence specific code in a follow-up patch.
> > 
> > Based on work by Peter De Schrijver <pdeschrijver@nvidia.com>.
> > 
> > Signed-off-by: Joseph Lo <josephl@nvidia.com>
> > Signed-off-by: Thierry Reding <treding@nvidia.com>
> > ---
> > Changes in v5:
> > - major rework and cleanup
> > 
> >  drivers/memory/tegra/tegra210-emc.c | 1952 +++++++++++++++++++++------
> >  drivers/memory/tegra/tegra210-emc.h |  893 +++++++++++-
> >  2 files changed, 2390 insertions(+), 455 deletions(-)
> > 
> > diff --git a/drivers/memory/tegra/tegra210-emc.c b/drivers/memory/tegra/tegra210-emc.c
> > index 80ea14d1e6ce..4ea8fb70a4fd 100644
> > --- a/drivers/memory/tegra/tegra210-emc.c
> > +++ b/drivers/memory/tegra/tegra210-emc.c
> > @@ -1,6 +1,6 @@
> >  // SPDX-License-Identifier: GPL-2.0
> >  /*
> > - * Copyright (c) 2015-2019, NVIDIA CORPORATION.  All rights reserved.
> > + * Copyright (c) 2015-2020, NVIDIA CORPORATION.  All rights reserved.
> >   */
> 
> Would be nice to avoid all the unnecessary changes, like the one above
> and then all the code's removals/reshuffling.
> 
> Such that a new patch was a clean addition to a previous patch, instead
> of a re-write.

I think this is the result of me messing up a rebase. The EMC driver
changes added in the clock driver patch should've been in this patch,
which would've made this a clean addition. I'll reshuffle the code
for the next revision.

Thanks for pointing that out.

Thierry

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