mmc: sdhci-esdhc-imx: add sd3.0 SDR clock tuning support
Freescale i.MX6Q/DL uSDHC clock tuning progress is a little different from the standard tuning process defined in host controller spec v3.0. Thus we use platform_execute_tuning instead of standard sdhci tuning. The main difference are: 1) not only generate Buffer Read Ready interrupt when tuning is performing. It generates all other DATA interrupts like the normal data command. 2) SDHCI_CTRL_EXEC_TUNING is not automatically cleared by HW, instead it's controlled by SW. 3) SDHCI_CTRL_TUNED_CLK is not automatically set by HW, it's controlled by SW. 4) the clock delay for every tuning is set by SW. Signed-off-by: Dong Aisheng <b29396@freescale.com> Acked-by: Shawn Guo <shawn.guo@linaro.org> Signed-off-by: Chris Ball <cjb@laptop.org>
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