[U-Boot] [PATCH 2/3] dm: blk: Add a note about boards that don't use block devices

[Simon Glass]

Not all boards use block devices. Those that do not should explicitly
disable CONFIG_BLK (and CONFIG_SPL_BLK if needed) to avoid any build
problems when CONFIG_BLK becomes the default.

Add a note to this effect.

Signed-off-by: Simon Glass <sjg at chromium.org>
---

 doc/driver-model/MIGRATION.txt | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/doc/driver-model/MIGRATION.txt b/doc/driver-model/MIGRATION.txt
index 5ebefd608b9..8d1c5e512db 100644
--- a/doc/driver-model/MIGRATION.txt
+++ b/doc/driver-model/MIGRATION.txt
@@ -19,6 +19,11 @@ time may be removed in a subsequent release.
 Note that this implies use of driver model for all block devices (e.g.
 MMC, USB, SCSI, SATA).
 
+If your board does not use block devices, please send patches to explicitly
+disable CONFIG_BLK in your Kconfig or defconfig files. Also disable
+CONFIG_SPL_BLK if necessary. CONFIG_BLK will default to on by January 2019.
+
+
 CONFIG_DM_SPI
 CONFIG_DM_SPI_FLASH
 -------------------
-- 
2.19.1.1215.g8438c0b245-goog