[PATCH v2 4/4] mtd: rawnand: qcom: scan all chips before registering MTD devices

[James Hilliard <james.hilliard1@gmail.com>]

Each NAND child is registered before the next child is scanned. Once a
chip is published, its MTD operations can run concurrently with the next
nand_scan(), which does not hold the controller lock. Both paths use
controller-wide command buffers, and attaching another chip can replace
the BAM transaction underneath an active transfer.

Initialize and scan every child before registering any MTD devices. Track
which chips have been registered so probe failure unregisters only those
devices while cleaning up every successfully scanned chip.

Fixes: 6a3cec64f18c ("mtd: rawnand: qcom: convert driver to nand_scan()")
Cc: stable@vger.kernel.org
Closes: https://lore.kernel.org/r/sashiko-outbox-204074@kernel.org/
Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
---
 drivers/mtd/nand/raw/qcom_nandc.c | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/drivers/mtd/nand/raw/qcom_nandc.c b/drivers/mtd/nand/raw/qcom_nandc.c
index 14bb7f3d6c36..978fa84f051d 100644
--- a/drivers/mtd/nand/raw/qcom_nandc.c
+++ b/drivers/mtd/nand/raw/qcom_nandc.c
@@ -89,6 +89,7 @@ struct qcom_op {
  * @use_ecc:			request the controller to use ECC for the
  *				upcoming read/write
  * @bch_enabled:		flag to tell whether BCH ECC mode is used
+ * @registered:		whether the MTD device has been registered
  */
 struct qcom_nand_host {
 	struct qcom_nand_boot_partition *boot_partitions;
@@ -118,6 +119,7 @@ struct qcom_nand_host {
 	bool codeword_fixup;
 	bool use_ecc;
 	bool bch_enabled;
+	bool registered;
 };
 
 static struct qcom_nand_host *to_qcom_nand_host(struct nand_chip *chip)
@@ -2008,9 +2010,9 @@ static int qcom_nand_host_parse_boot_partitions(struct qcom_nand_controller *nan
 	return 0;
 }
 
-static int qcom_nand_host_init_and_register(struct qcom_nand_controller *nandc,
-					    struct qcom_nand_host *host,
-					    struct device_node *dn)
+static int qcom_nand_host_init(struct qcom_nand_controller *nandc,
+			       struct qcom_nand_host *host,
+			       struct device_node *dn)
 {
 	struct nand_chip *chip = &host->chip;
 	struct mtd_info *mtd = nand_to_mtd(chip);
@@ -2059,10 +2061,6 @@ static int qcom_nand_host_init_and_register(struct qcom_nand_controller *nandc,
 			goto err;
 	}
 
-	ret = mtd_device_parse_register(mtd, probes, NULL, NULL, 0);
-	if (ret)
-		goto err;
-
 	return 0;
 
 err:
@@ -2082,7 +2080,7 @@ static int qcom_probe_nand_devices(struct qcom_nand_controller *nandc)
 		if (!host)
 			return -ENOMEM;
 
-		ret = qcom_nand_host_init_and_register(nandc, host, child);
+		ret = qcom_nand_host_init(nandc, host, child);
 		if (ret) {
 			devm_kfree(dev, host);
 			return ret;
@@ -2091,6 +2089,14 @@ static int qcom_probe_nand_devices(struct qcom_nand_controller *nandc)
 		list_add_tail(&host->node, &nandc->host_list);
 	}
 
+	list_for_each_entry(host, &nandc->host_list, node) {
+		ret = mtd_device_parse_register(nand_to_mtd(&host->chip),
+						probes, NULL, NULL, 0);
+		if (ret)
+			return ret;
+		host->registered = true;
+	}
+
 	return ret;
 }
 
@@ -2100,8 +2106,10 @@ static void qcom_nandc_cleanup_chips(struct qcom_nand_controller *nandc)
 	int ret;
 
 	list_for_each_entry_safe(host, tmp, &nandc->host_list, node) {
-		ret = mtd_device_unregister(nand_to_mtd(&host->chip));
-		WARN_ON(ret);
+		if (host->registered) {
+			ret = mtd_device_unregister(nand_to_mtd(&host->chip));
+			WARN_ON(ret);
+		}
 		nand_cleanup(&host->chip);
 		list_del(&host->node);
 	}

-- 
2.53.0