mmc: sdhci: remove tuning failure log for DDR50 mode

In SD 3.0 spec, there is no tuning for the DDR50 mode. In SD 3.0.1 spec,
tuning can be performed for the DDR50 mode. Most of the SD card are
only compliant with SD 3.0 spec. It leads to get some logs because the
tuning procedure, which is not supported, has failed. This log is
useless most of the time.

Signed-off-by: Ludovic Desroches <ludovic.desroches@microchip.com>

Author: ldesroches

drivers/mmc/host/sdhci.c

@@ -2108,8 +2108,17 @@ static void __sdhci_execute_tuning(struct sdhci_host *host, u32 opcode)
 		sdhci_send_tuning(host, opcode);
 
 		if (!host->tuning_done) {
-			pr_info("%s: Tuning timeout, falling back to fixed sampling clock\n",
-				mmc_hostname(host->mmc));
+			/*
+			 * Tuning for DDR50 mode appeared in the SD 3.0.1
+			 * specification. If the card is only compliant with
+			 * SD 3.0 and not SD 3.0.1 (as most of the SD cards),
+			 * CMD19 will fail. In this case, the failure is not
+			 * an error. It's useless to display that we fall back
+			 * to fixed sampling clock at each tuning procedure.
+			 */
+			if (host->timing != MMC_TIMING_UHS_DDR50)
+				pr_info("%s: Tuning timeout, falling back to fixed sampling clock\n",
+					mmc_hostname(host->mmc));
 			sdhci_abort_tuning(host, opcode);
 			return;
 		}