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Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hid6V-0004h1-IQ; Wed, 03 Jul 2019 11:07:11 +0000 Received: from bhuna.collabora.co.uk ([2a00:1098:0:82:1000:25:2eeb:e3e3]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1hid6P-0004g8-Dm for linux-mtd@lists.infradead.org; Wed, 03 Jul 2019 11:07:07 +0000 Received: from localhost (unknown [IPv6:2a01:e0a:2c:6930:5cf4:84a1:2763:fe0d]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: bbrezillon) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id 9BFB128A8B7; Wed, 3 Jul 2019 12:07:01 +0100 (BST) Date: Wed, 3 Jul 2019 13:06:58 +0200 From: Boris Brezillon To: Naga Sureshkumar Relli Subject: Re: [LINUX PATCH v17 2/2] mtd: rawnand: pl353: Add basic driver for arm pl353 smc nand interface Message-ID: <20190703130658.2abe5096@collabora.com> In-Reply-To: References: <20190625044630.31717-1-naga.sureshkumar.relli@xilinx.com> <20190625044630.31717-2-naga.sureshkumar.relli@xilinx.com> <20190703082544.5b0ea566@collabora.com> Organization: Collabora X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190703_040705_727654_4762CD3D X-CRM114-Status: GOOD ( 30.35 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "bbrezillon@kernel.org" , "helmut.grohne@intenta.de" , "richard@nod.at" , "linux-kernel@vger.kernel.org" , "marek.vasut@gmail.com" , "yamada.masahiro@socionext.com" , "linux-mtd@lists.infradead.org" , "miquel.raynal@bootlin.com" , Michal Simek , "computersforpeace@gmail.com" , "dwmw2@infradead.org" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org On Wed, 3 Jul 2019 08:57:57 +0000 Naga Sureshkumar Relli wrote: > Hi Boris, > > Thanks for the review. > > > -----Original Message----- > > From: Boris Brezillon > > Sent: Wednesday, July 3, 2019 11:56 AM > > To: Naga Sureshkumar Relli > > Cc: miquel.raynal@bootlin.com; helmut.grohne@intenta.de; richard@nod.at; > > dwmw2@infradead.org; computersforpeace@gmail.com; marek.vasut@gmail.com; > > vigneshr@ti.com; bbrezillon@kernel.org; yamada.masahiro@socionext.com; linux- > > mtd@lists.infradead.org; linux-kernel@vger.kernel.org > > Subject: Re: [LINUX PATCH v17 2/2] mtd: rawnand: pl353: Add basic driver for arm pl353 > > smc nand interface > > > > On Mon, 24 Jun 2019 22:46:30 -0600 > > Naga Sureshkumar Relli wrote: > > > > > > > + > > > +/** > > > + * pl353_nand_exec_op_cmd - Send command to NAND device > > > + * @chip: Pointer to the NAND chip info structure > > > + * @subop: Pointer to array of instructions > > > + * Return: Always return zero > > > + */ > > > +static int pl353_nand_exec_op_cmd(struct nand_chip *chip, > > > + const struct nand_subop *subop) { > > > + struct mtd_info *mtd = nand_to_mtd(chip); > > > + const struct nand_op_instr *instr; > > > + struct pl353_nfc_op nfc_op = {}; > > > + struct pl353_nand_controller *xnfc = to_pl353_nand(chip); > > > + unsigned long cmd_phase_data = 0, end_cmd_valid = 0; > > > + unsigned long end_cmd; > > > + unsigned int op_id, len; > > > + bool reading; > > > + u32 cmdphase_addrflags; > > > + > > > + pl353_nfc_parse_instructions(chip, subop, &nfc_op); > > > + instr = nfc_op.data_instr; > > > + op_id = nfc_op.data_instr_idx; > > > + pl353_smc_clr_nand_int(); > > > + > > > + /* Get the command phase address */ > > > + if (nfc_op.cmnds[1] != 0) { > > > + if (nfc_op.cmnds[0] == NAND_CMD_SEQIN) > > > + end_cmd_valid = 0; > > > + else > > > + end_cmd_valid = 1; > > > > You're testing the opcode, again. As I said several times, the > > ->exec_op() implementation should be opcode agnostic, it should just try > > to match sequences of -- cycles. > > > This driver uses common function for all patterns. > There was some discussion happened on v8 series > https://lore.kernel.org/patchwork/patch/933639/ > There the comments from Miquel was to use an optional property In the pattern > Matching, so with this approach, based on the command need to update the > end_cmd_valid bit in command phase cycle. > So in order to follow that approach, we defined a common pattern matching function > And there we are checking the commands. > It significantly reduces the code repetition. That's not what I'm talking about. I'm talking about the explicit 'nfc_op.cmnds[0] == NAND_CMD_SEQIN' check, which AFAICT, is wrong, or at the very least, not future-proof at all. Let me see if I understand what end_cmd_valid means: it's supposed to be set when the ADDR cycles are followed by a CMD cycle. You don't need to check if the first CMD cycle is !SEQIN (AKA start programming a page) to know that: just go through the flow of instructions in the subop, and check what's coming just after the ADDR instruction. > > I understand your concern about not to check any NAND command in the drivers > under ->exec_op() implementation. > But do you see any issues/impact with this? Yes, I do. Sorry to say that, but the whole driver is coded with specific use-cases (read/write page, read param page, etc) in mind, which is exactly what we were trying to avoid when designing exec_op(). The goal was to have something that's easily maintainable and does not break every time one tests a previously untested chip <-> controller combination. > Functionality wise Helmut tested each series and we addressed all the comments in v17 series. Just because it's been tested does not mean it's ready to be merged, sorry. > > Could you please let me know what do you say? > > > > + } > > > + > > > + end_cmd = nfc_op.cmnds[1]; > > > + > > > + /* > > > + * The SMC defines two phases of commands when transferring data to or > > > + * from NAND flash. > > > + * Command phase: Commands and optional address information are written > > > + * to the NAND flash.The command and address can be associated with > > > + * either a data phase operation to write to or read from the array, > > > + * or a status/ID register transfer. > > > + * Data phase: Data is either written to or read from the NAND flash. > > > + * This data can be either data transferred to or from the array, > > > + * or status/ID register information. > > > + */ > > > + cmdphase_addrflags = ((nfc_op.naddrs << ADDR_CYCLES_SHIFT) | > > > + (end_cmd_valid << END_CMD_VALID_SHIFT) | > > > + (COMMAND_PHASE) | > > > + (end_cmd << END_CMD_SHIFT) | > > > + (nfc_op.cmnds[0] << START_CMD_SHIFT)); > > > + > > > + /* Get the data phase address */ > > > + end_cmd_valid = 0; > > > + > > > + xnfc->dataphase_addrflags = ((0x0 << CLEAR_CS_SHIFT) | > > > + (end_cmd_valid << END_CMD_VALID_SHIFT) | > > > + (DATA_PHASE) | > > > + (end_cmd << END_CMD_SHIFT) | > > > + (0x0 << ECC_LAST_SHIFT)); > > > + > > > + /* Command phase AXI Read & Write */ > > > + if (nfc_op.naddrs >= 5) { > > > + if (mtd->writesize > PL353_NAND_ECC_SIZE) { > > > + cmd_phase_data = nfc_op.addrs; > > > + > > > + /* Another address cycle for devices > 128MiB */ > > > + if (chip->options & NAND_ROW_ADDR_3) { > > > > Clearly, none of this belongs in the ->exec_op() implementation. Looks like something related > > to page read... > As I mentioned above in comments of pl353_exec_op(), the PL353 SMC > Controller uses command phase and data phase. > And in the Command phase, command and optional addresses are written to NAND flash. > And it is correct as you said, it looks like page reads but it is actually a command phase address > update. You have the exact number of ADDR cycles to issue in the ADDR instruction, why do you need to check NAND_ROW_ADDR_3 at all? ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/