[PATCH master 3/3] mci: core: make execute_tuning mandatory for HS200

[Ahmad Fatoum]

We assume that any host controller that doesn't implement execute_tuning
will have no issue with HS200 operation. This is likely untrue for most
host drivers that we have and it will confuse users:

  - Enable CONFIG_MCI_TUNING, e.g. for i.MX
  - devinfo shows HS200 operation
  - Actually reading blocks will fail with EIO

Therefore, let's make execute_tuning mandatory for HS200. If some driver
doesn't need it, it can always define an empty stub for it.

Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
 drivers/mci/mci-core.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/mci/mci-core.c b/drivers/mci/mci-core.c
index af0980308866..f6565b2b64dd 100644
--- a/drivers/mci/mci-core.c
+++ b/drivers/mci/mci-core.c
@@ -1349,8 +1349,14 @@ int mci_execute_tuning(struct mci *mci)
 	struct mci_host *host = mci->host;
 	u32 opcode;
 
-	if (!host->execute_tuning)
-		return 0;
+	if (!host->execute_tuning) {
+		/*
+		 * For us, implementing ->execute_tuning is mandatory to
+		 * support higher speed modes
+		 */
+		dev_warn(&mci->dev, "tuning failed: no host diver support\n");
+		return -EOPNOTSUPP;
+	}
 
 	/* Tuning is only supported for MMC / HS200 */
 	if (mmc_card_hs200(mci))
-- 
2.39.2