The clean_bar() function resets the SPI NOR BAR register to 0, but does not set the flash->curr_bar to 0 , therefore those two can get out of sync, which could ultimatelly result in corrupted flash content.
The simplest test case is this:
=> mw 0x10000000 0x1234abcd 0x4000 => sf probe => sf erase 0x1000000 0x10000 => sf write 0x10000000 0x1000000 0x10000
=> sf probe ; sf read 0x12000000 0 0x10000 ; md 0x12000000
That is, erase a sector above the 16 MiB boundary and write it with random pre-configured data. What will actually happen without this patch is the sector will be erased, but the data will be written to BAR 0 offset 0x0 in the flash.
This is because the erase command will call write_bar()+clean_bar(), which will leave flash->bank_curr = 1 while the hardware BAR registers will be set to 0 through clean_bar(). The subsequent write will also trigger write_bar()+clean_bar(), but write_bar checks if the target bank == flash->bank_curr and if so, does NOT reconfigure the BAR in the SPI NOR. Since flash->bank_curr is still 1 and out of sync with the HW, the condition matches, BAR programming is skipped and write ends up at address 0x0, thus corrupting flash content.
Signed-off-by: Marek Vasut marex@denx.de Cc: Jagan Teki jagan@openedev.com Cc: Tom Rini trini@konsulko.com --- drivers/mtd/spi/spi_flash.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/mtd/spi/spi_flash.c b/drivers/mtd/spi/spi_flash.c index 2911729b28..1b61095859 100644 --- a/drivers/mtd/spi/spi_flash.c +++ b/drivers/mtd/spi/spi_flash.c @@ -128,6 +128,7 @@ static int clean_bar(struct spi_flash *flash) if (flash->bank_curr == 0) return 0; cmd = flash->bank_write_cmd; + flash->bank_curr = 0;
return spi_flash_write_common(flash, &cmd, 1, &bank_sel, 1); }