When the frequency on the nand chip pins is above 33MHz,
the nand EDO(extended Data Out) timing could be applied.
The GPMI implements a Feedback read strobe to sample the read data in
the EDO timing mode.
This patch adds the EDO feature for the gpmi-nand driver.
For some onfi nand chips, the mode 4 is the fastest;
while for other onfi nand chips, the mode 5 is the fastest.
This patch only adds the support for the fastest asynchronous timing mode.
So this patch only supports the mode 4 and mode 5.
I tested several Micron's ONFI nand chips with EDO enabled,
take Micron MT29F32G08MAA for example (in mode 5, 100MHz):
1) The test result BEFORE we add the EDO feature:
=================================================
mtd_speedtest: MTD device: 2
mtd_speedtest: MTD device size 209715200, eraseblock size 524288,
page size 4096, count of eraseblocks 400,
pages per eraseblock 128, OOB size 218
.......................................
mtd_speedtest: testing eraseblock read speed
mtd_speedtest: eraseblock read speed is 3632 KiB/s
.......................................
mtd_speedtest: testing page read speed
mtd_speedtest: page read speed is 3554 KiB/s
.......................................
mtd_speedtest: testing 2 page read speed
mtd_speedtest: 2 page read speed is 3592 KiB/s
.......................................
=================================================
2) The test result AFTER we add the EDO feature:
=================================================
mtd_speedtest: MTD device: 2
mtd_speedtest: MTD device size 209715200, eraseblock size 524288,
page size 4096, count of eraseblocks 400,
pages per eraseblock 128, OOB size 218
.......................................
mtd_speedtest: testing eraseblock read speed
mtd_speedtest: eraseblock read speed is 19555 KiB/s
.......................................
mtd_speedtest: testing page read speed
mtd_speedtest: page read speed is 17319 KiB/s
.......................................
mtd_speedtest: testing 2 page read speed
mtd_speedtest: 2 page read speed is 18339 KiB/s
.......................................
=================================================
3) The read data performance is much improved by more then 5 times.
Signed-off-by: Huang Shijie <b32955@freescale.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
995fbbf563