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From: Felix Fietkau <nbd@nbd.name>
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Date: Sat, 4 Nov 2017 07:40:23 +0100
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Subject: [PATCH] mtd: spi-nor: support limiting 4K sectors support based on
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flash size
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Some devices need 4K sectors to be able to deal with small flash chips.
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For instance, w25x05 is 64 KiB in size, and without 4K sectors, the
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entire chip is just one erase block.
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On bigger flash chip sizes, using 4K sectors can significantly slow down
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many operations, including using a writable filesystem. There are several
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platforms where it makes sense to use a single kernel on both kinds of
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devices.
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To support this properly, allow configuring an upper flash chip size
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limit for 4K sectors support.
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Signed-off-by: Felix Fietkau <nbd@nbd.name>
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---
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--- a/drivers/mtd/spi-nor/Kconfig
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+++ b/drivers/mtd/spi-nor/Kconfig
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@@ -29,6 +29,17 @@ config MTD_SPI_NOR_USE_4K_SECTORS
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Please note that some tools/drivers/filesystems may not work with
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4096 B erase size (e.g. UBIFS requires 15 KiB as a minimum).
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+config MTD_SPI_NOR_USE_4K_SECTORS_LIMIT
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+ int "Maximum flash chip size to use 4K sectors on (in KiB)"
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+ depends on MTD_SPI_NOR_USE_4K_SECTORS
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+ default "4096"
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+ help
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+ There are many flash chips that support 4K sectors, but are so large
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+ that using them significantly slows down writing large amounts of
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+ data or using a writable filesystem.
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+ Any flash chip larger than the size specified in this option will
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+ not use 4K sectors.
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+
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config SPI_ATMEL_QUADSPI
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tristate "Atmel Quad SPI Controller"
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depends on ARCH_AT91 || (ARM && COMPILE_TEST)
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--- a/drivers/mtd/spi-nor/spi-nor.c
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+++ b/drivers/mtd/spi-nor/spi-nor.c
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@@ -1648,10 +1648,12 @@ int spi_nor_scan(struct spi_nor *nor, co
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#ifdef CONFIG_MTD_SPI_NOR_USE_4K_SECTORS
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/* prefer "small sector" erase if possible */
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- if (info->flags & SECT_4K) {
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+ if ((info->flags & SECT_4K) && (mtd->size <=
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+ CONFIG_MTD_SPI_NOR_USE_4K_SECTORS_LIMIT * 1024)) {
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nor->erase_opcode = SPINOR_OP_BE_4K;
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mtd->erasesize = 4096;
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- } else if (info->flags & SECT_4K_PMC) {
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+ } else if ((info->flags & SECT_4K_PMC) && (mtd->size <=
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+ CONFIG_MTD_SPI_NOR_USE_4K_SECTORS_LIMIT * 1024)) {
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nor->erase_opcode = SPINOR_OP_BE_4K_PMC;
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mtd->erasesize = 4096;
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} else
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