From mboxrd@z Thu Jan 1 00:00:00 1970 From: boris.brezillon@bootlin.com (Boris Brezillon) Date: Wed, 29 Aug 2018 12:31:14 +0200 Subject: [RFC PATCH v2 2/2] mtd: rawnand: meson: add support for Amlogic NAND flash controller In-Reply-To: <5061c929-8db0-3f4c-ec34-303fc351dfdd@amlogic.com> 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> <9abf0461-159b-db45-9ded-3d6cb2cc64db@amlogic.com> <5061c929-8db0-3f4c-ec34-303fc351dfdd@amlogic.com> Message-ID: <20180829123114.4b67314b@bbrezillon> To: linus-amlogic@lists.infradead.org List-Id: linus-amlogic.lists.infradead.org On Wed, 29 Aug 2018 18:29:05 +0800 Liang Yang wrote: > On 8/29/2018 6:08 PM, Liang Yang wrote: > > > > 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. > there are two usages for NFC_CMD_RB. One reads the data status > continuously by hardware after sending 0x70 command; the other checks > the r/b IO status continuously.both can send irq when r/b is ready. Both should do what you expect, so I guess you're good.