linux-stable/drivers/mtd/nand
Herve Codina 9472335eaa mtd: rawnand: fsmc: Fix timing computation
Under certain circumstances, the timing settings calculated by
the FSMC NAND controller driver were inaccurate.
These settings led to incorrect data reads or fallback to
timing mode 0 depending on the NAND chip used.

The timing computation did not take into account the following
constraint given in SPEAr3xx reference manual:
  twait >= tCEA - (tset * TCLK) + TOUTDEL + TINDEL

Enhance the timings calculation by taking into account this
additional constraint.

This change has no impact on slow timing modes such as mode 0.
Indeed, on mode 0, computed values are the same with and
without the patch.

NANDs which previously stayed in mode 0 because of fallback to
mode 0 can now work at higher speeds and NANDs which were not
working at all because of the corrupted data work at high
speeds without troubles.

Overall improvement on a Micron/MT29F1G08 (flash_speed tool):
                        mode0       mode3
eraseblock write speed  3220 KiB/s  4511 KiB/s
eraseblock read speed   4491 KiB/s  7529 KiB/s

Fixes: d9fb079571 ("mtd: nand: fsmc: add support for SDR timings")
Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20211119150316.43080-5-herve.codina@bootlin.com
2021-12-03 14:33:45 +01:00
..
onenand mtd: onenand: samsung: drop Exynos4 and describe driver in KConfig 2021-09-29 00:35:27 +02:00
raw mtd: rawnand: fsmc: Fix timing computation 2021-12-03 14:33:45 +01:00
spi mtd: spinand: macronix: Add Quad support for serial NAND flash 2021-08-17 10:42:00 +02:00
bbt.c mtd: nand: bbt: Fix corner case in bad block table handling 2021-05-10 18:20:54 +02:00
core.c mtd: nand: Add helpers to manage ECC engines and configurations 2020-12-10 22:37:30 +01:00
ecc-sw-bch.c mtd: nand: ecc-bch: Use the public nsteps field 2021-03-11 09:37:28 +01:00
ecc-sw-hamming.c mtd: rawnand: Let callers use the bare Hamming helpers 2021-10-15 12:20:59 +02:00
ecc.c mtd: spinand: Allow the case where there is no ECC engine 2020-12-10 22:37:30 +01:00
Kconfig mtd: nand: Change dependency between the NAND and ECC cores 2020-12-10 22:37:32 +01:00
Makefile mtd: nand: ecc-hamming: Move Hamming code to the generic NAND layer 2020-12-10 22:37:29 +01:00