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When U-Boot started using SPDX tags we were among the early adopters and there weren't a lot of other examples to borrow from. So we picked the area of the file that usually had a full license text and replaced it with an appropriate SPDX-License-Identifier: entry. Since then, the Linux Kernel has adopted SPDX tags and they place it as the very first line in a file (except where shebangs are used, then it's second line) and with slightly different comment styles than us. In part due to community overlap, in part due to better tag visibility and in part for other minor reasons, switch over to that style. This commit changes all instances where we have a single declared license in the tag as both the before and after are identical in tag contents. There's also a few places where I found we did not have a tag and have introduced one. Signed-off-by: Tom Rini <trini@konsulko.com>
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