Hi Alexandru, On Mon, Jan 30, 2017 at 02:53:43PM -0800, Alexandru Gagniuc wrote: > This patch is designed to workaround an issue where an mt7620 will > hang after a reboot. This happens because the bootrom gets confused > when the SPI flash is left in 4-byte addressing mode. This change > makes sure that we can reboot the system under normal circumstances, > but does not protect against system crashes.
NACK. This should not be needed and also doesn't provide a reliable method to avoid the problem you describe, please rather try https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?id=3274ba26f27becfc4193ec6e229288140651f240 In case you are aware of boards which neither implement a proper reset of the flash chip nor use a flash chip which supports dedicated 4-byte opcodes, please let us know, in that case the fix might still be needed and at least provide a best-effort solution (which may still result in stuck under certain circumstances such as CPU resets triggered by watchdogs or in any way out of the kernel's control) Cheers Daniel > > Signed-off-by: Alexandru Gagniuc <ale...@adaptrum.com> > --- > ...Reset-chip-to-3-byte-addressing-on-system.patch | 65 > ++++++++++++++++++++++ > 1 file changed, 65 insertions(+) > create mode 100644 > target/linux/ramips/patches-4.4/0800-mtd-m25p80-Reset-chip-to-3-byte-addressing-on-system.patch > > diff --git > a/target/linux/ramips/patches-4.4/0800-mtd-m25p80-Reset-chip-to-3-byte-addressing-on-system.patch > > b/target/linux/ramips/patches-4.4/0800-mtd-m25p80-Reset-chip-to-3-byte-addressing-on-system.patch > new file mode 100644 > index 0000000..de4ee2c > --- /dev/null > +++ > b/target/linux/ramips/patches-4.4/0800-mtd-m25p80-Reset-chip-to-3-byte-addressing-on-system.patch > @@ -0,0 +1,65 @@ > +From 0f7fcc3dfc27a91e7672e9e589f3f558e8c41737 Mon Sep 17 00:00:00 2001 > +From: Alexandru Gagniuc <ale...@adaptrum.com> > +Date: Mon, 30 Jan 2017 13:30:33 -0800 > +Subject: [PATCH] mtd: m25p80: Reset chip to 3-byte addressing on system > reboot > + > +Some SOCs can not handle 4-byte addressing in their mask ROM. On such > +devices if we leave the SPI flash in 4-byte mode, then reboot the > +system, the device will not boot. > + > +Some SoCs have a special output to reset all the on-board peripherals. > +This pin should be connected to the !RESET pin of the flash as well. > +Unfortunately, not all boards implement this. As a workaround for such > +hardware, reset the SPI flash to 3-byte addressing mode. This does not > +protect against system crashes, but it does allow the system to reboot > +in the case of a normal reboot. > + > +Cc: Paul Fertser <fercer...@gmail.com> > +Signed-off-by: Alexandru Gagniuc <ale...@adaptrum.com> > +--- > + drivers/mtd/devices/m25p80.c | 15 +++++++++++++++ > + 1 file changed, 15 insertions(+) > + > +diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c > +index fe9ceb7..2151975 100644 > +--- a/drivers/mtd/devices/m25p80.c > ++++ b/drivers/mtd/devices/m25p80.c > +@@ -27,6 +27,9 @@ > + #include <linux/spi/flash.h> > + #include <linux/mtd/spi-nor.h> > + > ++#define OPCODE_RESET_ENABLE 0x66 > ++#define OPCODE_RESET 0x99 > ++ > + #define MAX_CMD_SIZE 6 > + struct m25p { > + struct spi_device *spi; > +@@ -168,6 +171,17 @@ static int m25p80_erase(struct spi_nor *nor, loff_t > offset) > + return 0; > + } > + > ++void m25p80_reboot(struct mtd_info *mtd) > ++{ > ++ struct spi_nor *nor = container_of(mtd, struct spi_nor, mtd); > ++ struct m25p *flash = nor->priv; > ++ > ++ flash->command[0] = OPCODE_RESET_ENABLE; > ++ spi_write(flash->spi, flash->command, 1); > ++ flash->command[0] = OPCODE_RESET; > ++ spi_write(flash->spi, flash->command, 1); > ++} > ++ > + /* > + * board specific setup should have ensured the SPI clock used here > + * matches what the READ command supports, at least until this driver > +@@ -197,6 +211,7 @@ static int m25p_probe(struct spi_device *spi) > + nor->erase = m25p80_erase; > + nor->write_reg = m25p80_write_reg; > + nor->read_reg = m25p80_read_reg; > ++ nor->mtd._reboot = m25p80_reboot; > + > + nor->dev = &spi->dev; > + nor->flash_node = spi->dev.of_node; > +-- > +2.9.3 > + > -- > 2.9.3 > > > _______________________________________________ > Lede-dev mailing list > Lede-dev@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/lede-dev _______________________________________________ Lede-dev mailing list Lede-dev@lists.infradead.org http://lists.infradead.org/mailman/listinfo/lede-dev
