Re: [RFC PATCH v2 2/2] mtd: rawnand: meson: add support for Amlogic NAND flash controller

Boris Brezillon
2018-08-24T12:48:30Z

On Wed, 22 Aug 2018 22:08:42 +0800
Liang Yang <liang.yang@amlogic.com> wrote:

> > You have to wait tWB, that's for sure.
> >
> we have a maximum 32 commands fifo. when command is written into
> NFC_REG_CMD, it doesn't mean that command is executing right now, maybe
> it is buffering on the queue.Assume one ERASE operation, when 2nd
> command(0xd0) is written into NFC_REG_CMD and then come into
> NAND_OP_WAITRDY_INSTR, if I read the RB status by register, it may be
> wrong because 0xd0 may not being executed. it is unusual unless
> buffering two many command.

You should flush the queue and wait for it to empty at the end of
->exec_op().

> so it seems that i still need to use nand_soft_waitrdy or wait cmd is
> executed somewhere.

Don't you have a WAIT_FOR_RB instruction? What is NFC_CMD_RB for? Also,
NFC_CMD_IDLE seems to allow you to add an arbitrary delay, and that's
probably what you should use for tWB.