From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Nelson <eric@nelint.com>
Date: Tue, 22 Dec 2015 07:47:47 -0700
Subject: [U-Boot] [PATCH 1/2] arm: imx6: Add DDR3 calibration code for
 MX6 Q/D/DL
In-Reply-To: <CAJ+vNU1pAfwQuWfn1zKYkFgi2yV0P-35XCYo5uKTOLd7h5cmqg@mail.gmail.com>
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 <56770222.1050108@nelint.com>
 <CAJ+vNU1pAfwQuWfn1zKYkFgi2yV0P-35XCYo5uKTOLd7h5cmqg@mail.gmail.com>
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Hi Tim,

On 12/21/2015 09:13 PM, Tim Harvey wrote:
> On Sun, Dec 20, 2015 at 11:31 AM, Eric Nelson <eric@nelint.com> wrote:
>> Hi Marek,
>>
> <snip>
>> I'd recommend passing parameters of mx6_ddr_sysinfo (input) and
>> mx6_mmdc_calibration (output) to this routine.
>>
> 
> I don't know that this would make sense. The mx6_ddr_sysinfo shouldn't
> be affected by calibration and the mx6_mmdc_calibration structure
> would not be used if you are using auto-calibration.
> 
> In fact, I recommend an additional patch that will call the
> auto-calibration functions in mx6_ddr3_cfg if it is passed a NULL for
> mx6_ddr_calibration.
> 

Using sysinfo allows simpler determination of things like bus size
and rtt_nom.

This should be based on a board's configuration instead of inferring
the parameters by reading and interpreting registers that must
have been set before the calls to do_write_level_calibration().

The DDR stress tool does this (read from registers) because it's
distributed as a binary and JTAG is used to configure things before
running.

The calibration parameter would be used in a subsequent patch to
add a "calibration" pseudo-board.

Regards,


Eric