From mboxrd@z Thu Jan 1 00:00:00 1970 From: liang.yang@amlogic.com (Liang Yang) Date: Wed, 29 Aug 2018 18:29:05 +0800 Subject: [RFC PATCH v2 2/2] mtd: rawnand: meson: add support for Amlogic NAND flash controller In-Reply-To: <9abf0461-159b-db45-9ded-3d6cb2cc64db@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> Message-ID: <5061c929-8db0-3f4c-ec34-303fc351dfdd@amlogic.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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. >> . >>