u-boot/board/freescale/mx6memcal/README
Eric Nelson baefb63a13 mx6: Add board mx6memcal for use in validating DDR
This is a virtual "board" that uses configuration files and
Kconfig to define the memory layout used by a real board during
the board bring-up process.

It generates an SPL image that can be loaded using imx_usb or
SB_LOADER.exe.

When run, it will generate a set of calibration constants for
use in either or both a DCD configuration file for boards that
use u-boot.imx or struct mx6_mmdc_calibration for boards that
boot via SPL.

In essence, it is a configurable, open-source variant of the
Freescale ddr-stress tool.

	https://community.nxp.com/docs/DOC-105652

File mx6memcal_defconfig configures the board for use with
mx6sabresd or mx6qsabreauto.

Signed-off-by: Eric Nelson <eric@nelint.com>
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
2018-01-03 13:58:51 +01:00

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mx6memcal - a tool for calibrating DDR on i.MX6 boards.
The mx6memcal board isn't a real board, but a tool for use in bring-up of
new i.MX6 board designs.
It provides a similar function to the tool from NXP([1]) with a number
of advantages:
1. It's open-source, so it's easier to change if needed.
Typical reasons for needing to change include the use of alternate
UARTs and PMIC initialization.
2. It produces an image that's directly loadable with imx_usb [2] or
SB_LOADER.exe [3].
The NXP tool requires either a cumbersome JTAG connection that
makes running the DDR very slow or a working U-Boot image that
suffers from a chicken-and-egg problem (i.e. where do you get the
DDR parameters for U-Boot?).
3. It doesn't prompt for parameters, so it's much faster to gather
data from multiple boards.
4. Parameters to the calibration process can be chosen through
'make menuconfig'.
When booted, the mx6memcal board will run the DDR calibration
routines and display the result in a form suitable for cut and
paste into struct mx6_mmdc_calibration. It can also optionally
produce output in a form usable in a DCD-style .cfg file.
Selections in Kconfig allow most system design settings to be chosen:
1. The UART number and pad configuration for the UART. Options
include support for the most frequent reference designs on
i.MX6DQ/SDL (SABRE Lite and SABRESD designs).
2. The memory bus width (64 and 32-bit)
3. The number of chip-selects in use
4. The type of DDR (DDR3 or LPDDR2). Note that LPDDR2 support
is incomplete as of this writing.
5. The type of DDR chips in use. This selection allows re-use of common
parts and four DDR3 and two LPDDR2 parts are currently defined
6. The On-die termination value for the DRAM lines
7. The DRAM drive strength
8. The RTT_NOM and RTT_WR termination settings
9. RALAT/WALAT latency values
References:
[1] - NXP DDR Stress Test Tool - https://community.nxp.com/docs/DOC-105652
[2] - Boundary Devices imx_usb_loader
https://github.com/boundarydevices/imx_usb_loader
[3] - Use of SB_Loader.exe
https://boundarydevices.com/windows-users-and-unbricking