mmc: renesas_sdhi: enforce manual correction for Gen3

HW engineers say that automatic tap correction cannot be used for HS400
in all R-Car Gen3 SoCs. So, check for that SDHI variant and disable it
when HS400 is about to be enabled.
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/20191217114034.13290-5-wsa+renesas@sang-engineering.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/renesas_sdhi_core.c

@@ -348,6 +348,12 @@ static void renesas_sdhi_hs400_complete(struct tmio_mmc_host *host)
 	sd_scc_write32(host, priv, SH_MOBILE_SDHI_SCC_DT2FF,
 		       priv->scc_tappos_hs400);
 
+	/* Gen3 can't do automatic tap correction with HS400, so disable it */
+	if (sd_ctrl_read16(host, CTL_VERSION) == SDHI_VER_GEN3_SDMMC)
+		sd_scc_write32(host, priv, SH_MOBILE_SDHI_SCC_RVSCNTL,
+			       ~SH_MOBILE_SDHI_SCC_RVSCNTL_RVSEN &
+			       sd_scc_read32(host, priv, SH_MOBILE_SDHI_SCC_RVSCNTL));
+
 	sd_scc_write32(host, priv, SH_MOBILE_SDHI_SCC_TMPPORT2,
 		       (SH_MOBILE_SDHI_SCC_TMPPORT2_HS400EN |
 			SH_MOBILE_SDHI_SCC_TMPPORT2_HS400OSEL) |