--- /dev/null
+From: Felix Fietkau <nbd@nbd.name>
+Date: Sat, 4 Nov 2017 07:40:23 +0100
+Subject: [PATCH] mtd: spi-nor: support limiting 4K sectors support based on
+ flash size
+
+Some devices need 4K sectors to be able to deal with small flash chips.
+For instance, w25x05 is 64 KiB in size, and without 4K sectors, the
+entire chip is just one erase block.
+On bigger flash chip sizes, using 4K sectors can significantly slow down
+many operations, including using a writable filesystem. There are several
+platforms where it makes sense to use a single kernel on both kinds of
+devices.
+
+To support this properly, allow configuring an upper flash chip size
+limit for 4K sectors support.
+
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+
+--- a/drivers/mtd/spi-nor/Kconfig
++++ b/drivers/mtd/spi-nor/Kconfig
+@@ -29,6 +29,17 @@ config MTD_SPI_NOR_USE_4K_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 MTD_SPI_NOR_USE_4K_SECTORS_LIMIT
++ int "Maximum flash chip size to use 4K sectors on (in KiB)"
++ depends on MTD_SPI_NOR_USE_4K_SECTORS
++ default "4096"
++ help
++ There are many flash chips that support 4K sectors, but are so large
++ that using them significantly slows down writing large amounts of
++ data or using a writable filesystem.
++ Any flash chip larger than the size specified in this option will
++ not use 4K sectors.
++
+ config SPI_ATMEL_QUADSPI
+ tristate "Atmel Quad SPI Controller"
+ depends on ARCH_AT91 || (ARM && COMPILE_TEST)
+--- a/drivers/mtd/spi-nor/spi-nor.c
++++ b/drivers/mtd/spi-nor/spi-nor.c
+@@ -1642,10 +1642,12 @@ int spi_nor_scan(struct spi_nor *nor, co
+
+ #ifdef CONFIG_MTD_SPI_NOR_USE_4K_SECTORS
+ /* prefer "small sector" erase if possible */
+- if (info->flags & SECT_4K) {
++ if ((info->flags & SECT_4K) && (mtd->size <=
++ CONFIG_MTD_SPI_NOR_USE_4K_SECTORS_LIMIT * 1024)) {
+ nor->erase_opcode = SPINOR_OP_BE_4K;
+ mtd->erasesize = 4096;
+- } else if (info->flags & SECT_4K_PMC) {
++ } else if ((info->flags & SECT_4K_PMC) && (mtd->size <=
++ CONFIG_MTD_SPI_NOR_USE_4K_SECTORS_LIMIT * 1024)) {
+ nor->erase_opcode = SPINOR_OP_BE_4K_PMC;
+ mtd->erasesize = 4096;
+ } else
projects / openwrt / staging / kaloz.git / commitdiff