[PATCH] mtd: nand: Support 'EXIT GET STATUS' command in nand_command_lp()

[Thomas Petazzoni]

Hello,

On Tue, 16 May 2017 18:35:45 +0200, Boris Brezillon wrote:
> READ0 is sometimes used to exit GET STATUS mode. When this is the case
> no address cycles are requested, and we can use this information to
> detect that READSTART should not be issued after READ0 or that we
> shouldn't wait for the chip to be ready.
> 
> Signed-off-by: Boris Brezillon <boris.brezillon at free-electrons.com>

Tested-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>

On Spear600, which has the FSMC NAND controller, on a platform with a
Micron SLC NAND with on-die ECC.

Tested both mtd_speedtest.ko and mtd_nandbiterrs.ko. The speedtest
shows a nice read speed improvements.

Before:

mtd_speedtest: eraseblock read speed is 8545 KiB/s
mtd_speedtest: page read speed is 8428 KiB/s
mtd_speedtest: 2 page read speed is 8486 KiB/s

After:

mtd_speedtest: eraseblock read speed is 9834 KiB/s
mtd_speedtest: page read speed is 9682 KiB/s
mtd_speedtest: 2 page read speed is 9756 KiB/s

The write and erase speeds are unchanged.

Thanks!

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com