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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 #3 (Red Hat Linux)) id 1jYAqD-0006sF-3X; Mon, 11 May 2020 15:59:41 +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 #3 (Red Hat Linux)) id 1jYAq9-0006nr-HW for linux-mtd@lists.infradead.org; Mon, 11 May 2020 15:59:39 +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 CF1FC2A0A4B; Mon, 11 May 2020 16:59:35 +0100 (BST) Date: Mon, 11 May 2020 17:59:32 +0200 From: Boris Brezillon To: Miquel Raynal Subject: Re: [PATCH v4 7/8] mtd: rawnand: arasan: Add new Arasan NAND controller Message-ID: <20200511175932.0864490d@collabora.com> In-Reply-To: <20200511174614.38058ec7@xps13> References: <20200508171339.8052-1-miquel.raynal@bootlin.com> <20200508171339.8052-8-miquel.raynal@bootlin.com> <20200510090314.10426b6e@collabora.com> <20200511170729.4766eeaa@xps13> <20200511173235.2e2fe467@collabora.com> <20200511174614.38058ec7@xps13> Organization: Collabora X-Mailer: Claws Mail 3.17.5 (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-20200511_085937_847461_414579C1 X-CRM114-Status: GOOD ( 32.25 ) 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: Mark Rutland , devicetree@vger.kernel.org, Michal Simek , Vignesh Raghavendra , Tudor Ambarus , Richard Weinberger , Rob Herring , linux-mtd@lists.infradead.org, Thomas Petazzoni , Naga Sureshkumar Relli 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 Mon, 11 May 2020 17:46:14 +0200 Miquel Raynal wrote: > Hi Boris, > > Boris Brezillon wrote on Mon, 11 May > 2020 17:32:35 +0200: > > > On Mon, 11 May 2020 17:07:29 +0200 > > Miquel Raynal wrote: > > > > > Hi Boris, > > > > > > Boris Brezillon wrote on Sun, 10 May > > > 2020 09:03:14 +0200: > > > > > > > On Fri, 8 May 2020 19:13:38 +0200 > > > > Miquel Raynal wrote: > > > > > > > > > +static int anfc_exec_op(struct nand_chip *chip, > > > > > + const struct nand_operation *op, > > > > > + bool check_only) > > > > > +{ > > > > > + int ret; > > > > > + > > > > > + if (check_only) > > > > > + return nand_op_parser_exec_op(chip, &anfc_op_parser, op, > > > > > + check_only); > > > > > > > > You should also check the DATA_IN/OUT size here ^. > > > > > > Here is my proposal: > > > > > > ---8<--- > > > > > > +static int anfc_check_op(struct nand_chip *chip, > > > + const struct nand_operation *op) > > > +{ > > > + int op_id; > > > + > > > + /* > > > + * The controller abstracts all the NAND operations and do not support > > > + * data only operations. > > > > * FIXME: The nand_op_parser framework should be extended to > > * support custom checks on DATA instructions. > > Oh you really want to extend the core for that? I thought having a > "check_op" helper like this was enough, as it gives enough freedom to > the controller driver to return all the corner cases that are not very > generic. See below for more details. Widespread enough to have at least 2 controllers needing that :P. Any code sharing is good to take IMO. > > > > > > + */ > > > > You also didn't mention the fact that the number of data cycles should > > be aligned on 4 bytes, and that the controller might read/write more > > than requested when that's not the case. But maybe you have that > > comment elsewhere in the code (where you do the round_up(4)?). > > Precisely, for me the previous check is not a problem from the core > perspective (hence not deserving a FIXME) because the driver do not lie > at any moment. Conversely, the driver limitations of what is supported > and what is not is clear and accurate. True, you can turn that into a TODO. That's still something I'd like to see shared. That's not to say we have to handle all weird cases in the core, we can simply add a ->check() hook to the pattern_elem so drivers can have custom per-element checks. > > However for this round_up() operation you are talking about, this is an > issue as we have currently no mean to say to the core that something > different than ordered was actually requested by the driver, so there > is lying involved and this deserves a FIXME. > > > > /* > > * Number of DATA cycles must be aligned on 4, that means the > > * controller might read/write more than requested This is > > * harmless most of the time as extra DATA are discarded in > > * the write path and read pointer adjusted in the read path. > > * FIXME: The core should mark operations where reading/writing > > * more is allowed so the exec_op() implementation can take > > * the right decision when the alignment constraint is not met: > > * adjust the number of DATA cycles when it's allowed, and > > * reject the operation otherwise. > > */ > > I want to put this comment where the round_up takes place. Sounds good. > > > > > > + for (op_id = 0; op_id < op->ninstrs; op_id++) { > > > + instr = &op->instrs[op_id]; > > > + > > > + switch (instr->type) { > > > + case NAND_OP_ADDR_INSTR: > > > + if (instr->ctx.addr.naddrs > ANFC_MAX_ADDR_CYC) > > > + return -ENOTSUPP; > > > + break; > > > + case NAND_OP_DATA_IN_INSTR: > > > + case NAND_OP_DATA_OUT_INSTR: > > > + if (instr->ctx.data.len > ANFC_MAX_CHUNK_SIZE) > > > + return -ENOTSUPP; > > > + break; > > > + default: > > > + } > > > + } > > > + > > > + /* > > > + * The controller does not allow to proceed with a CMD+DATA_IN cycle > > > + * manually on the bus by reading data from the data register. Instead, > > > + * the controller abstract a status read operation with its own status > > > + * register after ordering a read status operation. Hence, we cannot > > > + * support any CMD+DATA_IN operation other than a READ STATUS. > > > > * FIXME: The nand_op_parser() framework should be extended to > > * describe fixed patterns instead of open-coding this check > > * here. > > For this one, I am not against a FIXME as this is something that might > be useful for other drivers too. Maybe TODO more than FIXME, you're right. ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/