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Thu, 22 Oct 2026 13:27:54 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 09DEF10328E5A; Thu, 22 Oct 2026 15:27:42 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1792675674; h=from:subject:date:message-id:to:cc:mime-version:content-type: in-reply-to:references; bh=/RgtJAwfFxMYwKRHR6ym49yRh7I5Fuz2Xy5zLf91xb0=; b=Ru3JWSa450e+Pfh7Wr17MJeuBSndDLoX6yuq1Glk2pUuKCdE1g4SjrOYTy2wcqGbi8Im44 6FBKurVqPmB8fnoWsPyKf6mZnMyI86GP8R4S12gtVfD54xLKf0sHmb9+uxtHlFGRtUzQ5/ qYaXjWHsbgHVJvd5OdKM6JPqrqFw+griRskl1Hn0N478/R7oIdsLavPNBmZLY/cnQon8qg 2WrJpEFPRLkpUVnXPP3SHARlEXMdHbuiDioYFO0apGaJPyp6EIKek8VimAaDejD8vyT2jo KdJIrleI4voqKPvz0C47SBNgZLW646ZZnceeyj4p9E2dhJHkW5aMMbhORDQUYg== From: Miquel Raynal To: "Michael Walle" Cc: "Changhuang Liang" , "Pratyush Yadav" , "Takahiro Kuwano" , "Mark Brown" , "Richard Weinberger" , "Vignesh Raghavendra" , , , Subject: Re: [PATCH v1 2/4] mtd: spi-nor: Support mixed 1S-xD-xD DTR protocols in spi_nor_spimem_setup_op() In-Reply-To: (Michael Walle's message of "Thu, 22 Oct 2026 14:19:27 +0200") References: <20261022102614.75696-1-changhuang.liang@starfivetech.com> <20261022102614.75696-3-changhuang.liang@starfivetech.com> <875wyuqaj4.fsf@bootlin.com> User-Agent: mu4e 1.12.12; emacs 30.2 Date: Thu, 22 Oct 2026 15:27:42 +0200 Message-ID: <87ik2tq301.fsf@bootlin.com> X-Archived-By: MIME-Version: 1.0 X-Last-TLS-Session-Version: TLSv1.3 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261022_062758_789139_7E8AE494 X-CRM114-Status: GOOD ( 16.27 ) X-Spam-Score: -2.1 (--) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux MTD discussion mailing list List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-mtd" X-Spam-Status: No, score=-13.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_EF,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 22/10/2026 at 14:19:27 +02, "Michael Walle" wrote: > On Thu Oct 22, 2026 at 12:45 PM CEST, Miquel Raynal wrote: >> On 22/10/2026 at 03:26:12 -07, Changhuang Liang wrote: >> >>> Currently spi_nor_spimem_setup_op() sets all four phases (cmd, addr, >>> dummy, data) to DTR whenever spi_nor_protocol_is_dtr(proto) is true. >>> This is too coarse: the 1S-xD-xD DTR protocols (1_1_1_DTR, 1_2_2_DTR, >>> 1_4_4_DTR, 1_8_8_DTR) send the command phase in STR on a single line, >>> and only the address, dummy and data phases in DTR. SPIMEM supports >>> such mixed DTR modes. >>> >>> Split the handling: >>> >>> - For SNOR_PROTO_8_8_8_DTR, keep the existing behavior: set all >>> phases to DTR and use a 2-byte opcode (opcode + extension). >>> >>> - For the other DTR protocols, set the command phase to STR and only >>> the address, dummy and data phases to DTR. Double op->dummy.nbytes >>> since DTR transfers 2 bytes per clock cycle, matching how the dummy >>> cycle count is specified for these protocols. >>> >>> No in-tree flash currently declares SNOR_HWCAPS_READ_1_x_x_DTR, so >>> this is not a bug fix but preparation for enabling these protocols. >>> A follow-up patch will enable 1S-4D-4D for the MX66L1G45G. The >>> 8D-8D-8D path is unchanged. >>> >>> Signed-off-by: Changhuang Liang >>> --- >>> drivers/mtd/spi-nor/core.c | 21 ++++++++++++++------- >>> 1 file changed, 14 insertions(+), 7 deletions(-) >>> >>> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c >>> index 90524c58602e..43e506e728ab 100644 >>> --- a/drivers/mtd/spi-nor/core.c >>> +++ b/drivers/mtd/spi-nor/core.c >>> @@ -97,13 +97,7 @@ void spi_nor_spimem_setup_op(const struct spi_nor *nor, >>> if (op->data.nbytes) >>> op->data.buswidth = spi_nor_get_protocol_data_nbits(proto); >>> >>> - if (spi_nor_protocol_is_dtr(proto)) { >>> - /* >>> - * SPIMEM supports mixed DTR modes, but right now we can only >>> - * have all phases either DTR or STR. IOW, SPIMEM can have >>> - * something like 4S-4D-4D, but SPI NOR can't. So, set all 4 >>> - * phases to either DTR or STR. >>> - */ >>> + if (proto == SNOR_PROTO_8_8_8_DTR) { >>> op->cmd.dtr = true; >>> op->addr.dtr = true; >>> op->dummy.dtr = true; >>> @@ -115,6 +109,19 @@ void spi_nor_spimem_setup_op(const struct spi_nor *nor, >>> ext = spi_nor_get_cmd_ext(nor, op); >>> op->cmd.opcode = (op->cmd.opcode << 8) | ext; >>> op->cmd.nbytes = 2; >>> + } else if (spi_nor_protocol_is_dtr(proto)) { >>> + /* >>> + * 1S-xD-xD protocols: the opcode is sent in STR on a single >>> + * line, only the address, dummy and data phases are DTR. The >>> + * opcode stays 1 byte (no command extension). >>> + */ >>> + op->cmd.dtr = false; >>> + op->addr.dtr = true; >>> + op->dummy.dtr = true; >>> + op->data.dtr = true; >> >> Still to coarse IMHO. too* >> What about xS-xS-xD? > > Is this a thing? Are there any NOR flashes which support the address > being SDR? That doesn't make much sense, does it? The command being > SDR makes sense because you don't have to switch modes and thus > you're stateless. I honnestly don't know if it's actually a thing today in SPI NOR, but it is in SPI NAND. Just rising the flag. ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/