[U-Boot] [PATCH 1/2] arm: imx6: Add DDR3 calibration code for MX6 Q/D/DL

[Marek Vasut]

On Wednesday, December 16, 2015 at 04:00:38 PM, Eric Nelson wrote:
> Hi Marek,
> 
> On 12/16/2015 07:40 AM, Marek Vasut wrote:
> > Add DDR3 calibration code for i.MX6Q, i.MX6D and i.MX6DL. This code
> > fine-tunes the behavior of the MMDC controller in order to improve
> > the signal integrity and memory stability.
> 
> I'm glad to see that others are interested in this.
> 
> I've been working on something similar, but struggling to have time
> to finish and clean it up:
> 	https://github.com/ericnelsonaz/u-boot/tree/memcal-pass1
> 
> My aim is/was a bit different though, and aims to be a replacement for
> the DDR stress tool, which is cumbersome to use.

Excellent, we can add this as an optional feature or something which can
be triggered by command, since the "full" calibration takes some time.

> To do that, I put together a pseudo-board with Kconfig options for
> the serial console, memory bus width, and such.

Or maybe this can be built as a mutated SPL ?

> > Signed-off-by: Marek Vasut <marex at denx.de>
> > Cc: Stefano Babic <sbabic at denx.de>
> > ---
> > 
> >  arch/arm/cpu/armv7/mx6/ddr.c            | 559
> >  ++++++++++++++++++++++++++++++++
> >  arch/arm/include/asm/arch-mx6/mx6-ddr.h |   5 +
> >  2 files changed, 564 insertions(+)
> > 
> > diff --git a/arch/arm/cpu/armv7/mx6/ddr.c b/arch/arm/cpu/armv7/mx6/ddr.c
> > index 6b039e4..194411f 100644
> > --- a/arch/arm/cpu/armv7/mx6/ddr.c
> > +++ b/arch/arm/cpu/armv7/mx6/ddr.c
> > @@ -13,6 +13,565 @@
> > 
> >  #include <asm/io.h>
> >  #include <asm/types.h>
> 
> I'll review this in detail later, but off-hand, I think this could use
> a new CONFIG_ variable to exclude it from boards that don't use it.
> 
> It also shouldn't be difficult to support i.MX6SL and LPDDR here.

This is OK, the code will be compiled for these MX6 variants, but it will
be dropped from the final binary if you don't call it explicitly (see patch
2/2).

I don't have SX/SL, so I couldn't test it there.

Thanks!

> > +#if defined(CONFIG_MX6QDL) || defined(CONFIG_MX6Q) ||
> > defined(CONFIG_MX6D) +
> > +static int wait_for_bit(void *reg, const uint32_t mask, bool set)
> > +{
> > +	unsigned int timeout = 1000;
> > +	u32 val;
> > +
> 
> Regards,
> 
> 
> Eric

Best regards,
Marek Vasut