mmc: sdhci-esdhc-imx: Reset before sending tuning command for manual tuning

According to IC suggestion, everytime before sending the tuning command,
need to reset the usdhc, so to reset the tuning circuit, to let every
tuning command work well for the manual tuning method. For standard tuning
method, IC already add the reset operation in the hardware logic.

Signed-off-by: Haibo Chen <[e-mail]>
Acked-by: Adrian Hunter <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Ulf Hansson <[e-mail]>

drivers/mmc/host/sdhci-esdhc-imx.c

···
 static void esdhc_prepare_tuning(struct sdhci_host *host, u32 val)
 {
 	u32 reg;
+	u8 sw_rst;
+	int ret;
 
 	/* FIXME: delay a bit for card to be ready for next tuning due to errors */
 	mdelay(1);
+
+	/* IC suggest to reset USDHC before every tuning command */
+	esdhc_clrset_le(host, 0xff, SDHCI_RESET_ALL, SDHCI_SOFTWARE_RESET);
+	ret = readb_poll_timeout(host->ioaddr + SDHCI_SOFTWARE_RESET, sw_rst,
+				!(sw_rst & SDHCI_RESET_ALL), 10, 100);
+	if (ret == -ETIMEDOUT)
+		dev_warn(mmc_dev(host->mmc),
+		"warning! RESET_ALL never complete before sending tuning command\n");
 
 	reg = readl(host->ioaddr + ESDHC_MIX_CTRL);
 	reg |= ESDHC_MIX_CTRL_EXE_TUNE | ESDHC_MIX_CTRL_SMPCLK_SEL |