tree b07ce8bb9bab8f6cccb0e0732321b3c15b7ad29b
parent c73f04ea86c589d4b48b6ea44726d75ceaa4e4f2
author Faiz Abbas <faiz_abbas@ti.com> 1612431653 +0530
committer Lokesh Vutla <lokeshvutla@ti.com> 1612451277 +0530

mmc: am654_sdhci: Add support for software tuning

With the new SW tuning App note[1], a custom tuning algorithm is
required for eMMC HS200, HS400 and SD card UHS modes. The algorithm
involves running through the 32 possible input tap delay values and
sending the appropriate tuning command (CMD19/21) for each of them
to get a fail or pass result for each of the values. Typically, the
range will have a small contiguous failing window. Considering the
tuning range as a circular buffer, the algorithm then sets a final
tuned value directly opposite to the failing window.

[1] https://www.ti.com/lit/pdf/spract9

Signed-off-by: Faiz Abbas <faiz_abbas@ti.com>
Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>