mtd: spi-nor: add Kconfig option to disable 4K sectors
Current situation with 4K sectors is quite messy. First of all, some
MTD "users" don't work with such small size. An example may be UBIFS
which requires 15 KiB erase blocks as a minimum. In theory spi-nor
should provide multiple erase regions and MTD "users" should use the
one they need. Unforunately that is not implemented.
In the result our flashes database in spi-nor is hackish. For some
flashes we pretend they don't support 4K sectors just because some
distribution uses UBIFS on it. This ofc leads to conflicts, like
Samsung using w25q128 with 4K sectors vs. OpenWrt requiring it to
pretend it's 64 KiB blocks only.
My idea (plan?) for fixing this situation:
1) Use real hw info (this requires a way for disabling 4K for now)
2) Provide detailed info about erase regions
3) Make UBIFS work with devices that support 4K sectors
Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
diff --git a/drivers/mtd/spi-nor/Kconfig b/drivers/mtd/spi-nor/Kconfig
index f8acfa4..64a4f0e 100644
--- a/drivers/mtd/spi-nor/Kconfig
+++ b/drivers/mtd/spi-nor/Kconfig
@@ -7,6 +7,20 @@
if MTD_SPI_NOR
+config MTD_SPI_NOR_USE_4K_SECTORS
+ bool "Use small 4096 B erase sectors"
+ default y
+ help
+ Many flash memories support erasing small (4096 B) sectors. Depending
+ on the usage this feature may provide performance gain in comparison
+ to erasing whole blocks (32/64 KiB).
+ Changing a small part of the flash's contents is usually faster with
+ small sectors. On the other hand erasing should be faster when using
+ 64 KiB block instead of 16 × 4 KiB sectors.
+
+ Please note that some tools/drivers/filesystems may not work with
+ 4096 B erase size (e.g. UBIFS requires 15 KiB as a minimum).
+
config SPI_FSL_QUADSPI
tristate "Freescale Quad SPI controller"
depends on ARCH_MXC