mtd: rawnand: Add and use helper for testing data interface

From: Rickard x Andersson <[email protected]>

This helper checks if the controller supports the current data interface timings. If the timings are not supported the vendor provided corresponding onfi mode will be tried, and if that fails we will fall back to onfi mode 0.

The helper can also be used by NAND vendor driver for testing different timings.

Signed-off-by Rickard x Andersson <[email protected]>

---
 drivers/mtd/nand/raw/internals.h | 24 ++++++++++++++++++++++++
 drivers/mtd/nand/raw/nand_base.c | 28 ++++++++++++++++++----------
 2 files changed, 42 insertions(+), 10 deletions(-)

drivers/mtd/nand/raw/internals.h +24 -0

index 615677820338..6dacf110b559 100644
@@ -148,6 +148,30 @@ static inline bool nand_can_choose_data_interface(struct nand_chip *chip)
 	return chip->ops.choose_data_interface;
 }
 
+/**
+ * nand_controller_supports_data_interface - Check if controller can handle
+ * the current timings.
+ *
+ * @chip: The NAND chip
+ */
+static inline int
+nand_controller_supports_data_interface(struct nand_chip *chip)
+{
+	int ret;
+	const struct nand_controller_ops *ops = chip->controller->ops;
+
+	/*
+	 * Pass NAND_DATA_IFACE_CHECK_ONLY to only check if the
+	 * controller supports the requested timings.
+	 */
+	ret = ops->setup_data_interface(chip,
+					NAND_DATA_IFACE_CHECK_ONLY,
+					&chip->data_interface);
+
+	return ret;
+}
+
+
 /* BBT functions */
 int nand_markbad_bbt(struct nand_chip *chip, loff_t offs);
 int nand_isreserved_bbt(struct nand_chip *chip, loff_t offs);

drivers/mtd/nand/raw/nand_base.c +16 -5

index c42cbeb7e446..e3c57649380b 100644
@@ -982,8 +982,24 @@ static int nand_choose_data_interface(struct nand_chip *chip)
 	 */
 	if (nand_can_choose_data_interface(chip)) {
 		ret = chip->ops.choose_data_interface(chip);
+		if (ret)
+			return ret;
+
+		/*
+		 * Check if the controller can handle the NAND vendor specific
+		 * best timings.
+		 */
+		ret = nand_controller_supports_data_interface(chip);
 		if (!ret)
 			return ret;
+
+		/*
+		 * Specific timings did not work, try using corresponding
+		 * onfi mode provided by vendor.
+		 */
+		if (chip->data_interface.timings.mode)
+			chip->default_timing_mode =
+				chip->data_interface.timings.mode;
 	}
 
 	/*

@@ -994,9 +1010,6 @@ static int nand_choose_data_interface(struct nand_chip *chip)
 	if (chip->parameters.onfi) {
 		modes = chip->parameters.onfi->async_timing_mode;
 	} else {
-		if (!chip->default_timing_mode)
-			return 0;
-
 		modes = GENMASK(chip->default_timing_mode, 0);
 	}
 

@@ -1005,13 +1018,8 @@ static int nand_choose_data_interface(struct nand_chip *chip)
 		if (ret)
 			continue;
 
-		/*
-		 * Pass NAND_DATA_IFACE_CHECK_ONLY to only check if the

Actually I think what Boris had in mind was a little bit different. As the "preparation series" has not been sent over the mailing list yet, if you don't mind, I will drop patch 1/2 which is not needed after my latest changes and take your second patch, adapted to the latest changes too. I am not taking the ownership of your series, just proposing the big picture and provide a more usual way to review the patches than a Github branch. Then, I'll might ask you to respin the entire series as well if needed.

Thanks,
Miquèl