[PATCH 1/2] dm: core: Fix iteration over driver_info records

[Paul Barker]

We should only perform additional iteration steps when needed to
initialize the parent of a device. Other binding errors (such as a
missing driver) should not lead to additional iteration steps.

Unnecessary iteration steps can cause issues when memory is tightly
constrained (such as in the TPL/SPL) since device_bind_by_name()
unconditionally allocates memory for a struct udevice. On the SanCloud
BBE this led to boot failure caused by memory exhaustion in the SPL
when booting from SPI flash.

Signed-off-by: Paul Barker <paul.barker at sancloud.com>
---
 drivers/core/lists.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/drivers/core/lists.c b/drivers/core/lists.c
index c49695b24f00..82d479564121 100644
--- a/drivers/core/lists.c
+++ b/drivers/core/lists.c
@@ -51,13 +51,13 @@ struct uclass_driver *lists_uclass_lookup(enum uclass_id id)
 	return NULL;
 }
 
-static int bind_drivers_pass(struct udevice *parent, bool pre_reloc_only)
+static bool bind_drivers_pass(struct udevice *parent, bool pre_reloc_only,
+			      int *result)
 {
 	struct driver_info *info =
 		ll_entry_start(struct driver_info, driver_info);
 	const int n_ents = ll_entry_count(struct driver_info, driver_info);
 	bool missing_parent = false;
-	int result = 0;
 	int idx;
 
 	/*
@@ -98,12 +98,12 @@ static int bind_drivers_pass(struct udevice *parent, bool pre_reloc_only)
 				drt->dev = dev;
 		} else if (ret != -EPERM) {
 			dm_warn("No match for driver '%s'\n", entry->name);
-			if (!result || ret != -ENOENT)
-				result = ret;
+			if (!*result || ret != -ENOENT)
+				*result = ret;
 		}
 	}
 
-	return result ? result : missing_parent ? -EAGAIN : 0;
+	return missing_parent;
 }
 
 int lists_bind_drivers(struct udevice *parent, bool pre_reloc_only)
@@ -117,13 +117,8 @@ int lists_bind_drivers(struct udevice *parent, bool pre_reloc_only)
 	 * always succeed on the first pass.
 	 */
 	for (pass = 0; pass < 10; pass++) {
-		int ret;
-
-		ret = bind_drivers_pass(parent, pre_reloc_only);
-		if (!ret)
+		if (!bind_drivers_pass(parent, pre_reloc_only, &result))
 			break;
-		if (ret != -EAGAIN && !result)
-			result = ret;
 	}
 
 	return result;
-- 
2.25.1