[re-picked]mmc: sdhci-of-at91: do not advertise SDR104 mode support

There are several issues with SDR104 mode and tuning so remove it from
the capabilities of the host controller.

Signed-off-by: Ludovic Desroches <ludovic.desroches@microchip.com>
[eugen.hristev@microchip.com: re-pick this commit was removed with upstream patch]
Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>

Author: ehristev

drivers/mmc/host/sdhci-of-at91.c

@@ -256,6 +256,18 @@ static int sdhci_at91_set_clks_presets(struct device *dev)
 	caps0 = readl(host->ioaddr + SDHCI_CAPABILITIES);
 	caps1 = readl(host->ioaddr + SDHCI_CAPABILITIES_1);
 
+	/*
+	* We experience some issues with SDR104. If the SD clock is higher
+	* than 100 MHz, we can get data corruption. With a 100 MHz clock,
+	* the tuning procedure may fail. For those reasons, it is useless to
+	* advertise that we can use SDR104 mode, so remove it from
+	* the capabilities.
+	*/
+	writel(SDMMC_CACR_KEY | SDMMC_CACR_CAPWREN, host->ioaddr + SDMMC_CACR);
+	caps1 &= (~SDHCI_SUPPORT_SDR104);
+	writel(caps1, host->ioaddr + SDHCI_CAPABILITIES_1);
+	writel(0, host->ioaddr + SDMMC_CACR);
+
 	gck_rate = clk_get_rate(priv->gck);
 	if (priv->soc_data->baseclk_is_generated_internally)
 		clk_base_rate = gck_rate / priv->soc_data->divider_for_baseclk;