According to JEDEC Spec, there is no need to do tuning under HS400 mode since the Rx signal is aligned with the DS signal. However, MediaTek's IC need set its "DS delay" internally to ensure it can latch Rx signal correctly. In previous version, We provide an "hs400-ds-delay" in device tree to cover different chipset/PCB design, and it works fine in most cases. But, with the development of process technology and the big VCore voltage scale range(may have 0.7V/0.6V/0.55V), it is difficult to find a suitable "hs400-ds-delay" to cover all of IC corner cases(SSSS/TTTT/FFFF). So that We must have the ability to do hs400 online tuning. Signed-off-by: Wenbin Mei <wenbin.mei@mediatek.com> Reviewed-by: Chaotian Jing <chaotian.jing@mediatek.com> Link: https://lore.kernel.org/r/20210917124803.22871-4-wenbin.mei@mediatek.com Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Linux kernel ============ There are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. Please read Documentation/admin-guide/README.rst first. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. The formatted documentation can also be read online at: https://www.kernel.org/doc/html/latest/ There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.
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