From mboxrd@z Thu Jan 1 00:00:00 1970 From: liang.yang@amlogic.com (Liang Yang) Date: Wed, 29 Aug 2018 18:08:05 +0800 Subject: [RFC PATCH v2 2/2] mtd: rawnand: meson: add support for Amlogic NAND flash controller In-Reply-To: <20180828152645.457dab5c@bbrezillon> References: <20180719094612.5833-1-yixun.lan@amlogic.com> <20180719094612.5833-3-yixun.lan@amlogic.com> <20180801235045.5b4d8211@bbrezillon> <42877a0d-9830-0626-3f64-e49a326eaa3c@amlogic.com> <20180817155608.5929b37a@bbrezillon> <96e538a5-1232-11f2-8b9e-5ddb09dcc2de@amlogic.com> <20180824144810.31c929a5@bbrezillon> <20180828152645.457dab5c@bbrezillon> Message-ID: <9abf0461-159b-db45-9ded-3d6cb2cc64db@amlogic.com> To: linus-amlogic@lists.infradead.org List-Id: linus-amlogic.lists.infradead.org On 8/28/2018 9:26 PM, Boris Brezillon wrote: > On Tue, 28 Aug 2018 21:21:48 +0800 > Liang Yang wrote: > >> Hi Boris, >> >> On 8/24/2018 8:48 PM, Boris Brezillon wrote: >>> On Wed, 22 Aug 2018 22:08:42 +0800 >>> Liang Yang 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. >>> >>> em, I can wait for RB by reading the status from register now. but when >> calling nand_soft_waitrdy, i really met a problem. One *jiffies* is >> about 4ms. When programming, it pass 1ms to >> instr->ctx.waitrdy.timeout_ms and nand_soft_waitrdy will be only one >> *jiffies* to reach timeout. And then calling nand_soft_waitrdy maybe at >> the tail of 4ms interval, it may only wait 100us and next jiffies >> arrive. Is it correct? > > Hm, no. If you initialize the time you compare to (using time_before() > or time_after()) correctly it should not happen. Anyway, I keep thinking > this is not how it should be done. Did you try NFC_CMD_RB? Did you ask > HW designers what it was created for? > I am using NFC_CMD_RB and checking with irq. it is ok now. > . >