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Fri, 07 May 2021 15:57:00 +0000 Received: from ssl.serverraum.org (web.serverraum.org [172.16.0.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ssl.serverraum.org (Postfix) with ESMTPSA id 0904C22172; Fri, 7 May 2021 17:56:50 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=walle.cc; s=mail2016061301; t=1620403010; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=RlX56EVKnATFSbY1WCdGnFQlG9+VgC6LS9QI7u1IDuQ=; b=V8ZJFE6qkF+ARhwG4oqTCd375XiOM55ni++FlIQz05gVb2qIvUQYycjU+TS1awwla7S6PU wLlOGRvbHtnVfqqg2rs/pusnMuK7b5y5k9c8aT8ozXbGR4iK8WxRBbooQr+CqDUO5LebE0 kAUqz3H+nsRQ2X9IPnPGu9vI197spv4= MIME-Version: 1.0 Date: Fri, 07 May 2021 17:56:49 +0200 From: Michael Walle To: Pratyush Yadav Cc: Tudor Ambarus , Miquel Raynal , Richard Weinberger , Vignesh Raghavendra , Mark Brown , linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org Subject: Re: [PATCH 6/6] mtd: spi-nor: core; avoid odd length/address writes in 8D-8D-8D mode In-Reply-To: <20210506191829.8271-7-p.yadav@ti.com> References: <20210506191829.8271-1-p.yadav@ti.com> <20210506191829.8271-7-p.yadav@ti.com> User-Agent: Roundcube Webmail/1.4.11 Message-ID: <497da81bb1531b085941ea2e711cf9b6@walle.cc> X-Sender: michael@walle.cc X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210507_085658_372013_DF683DC6 X-CRM114-Status: GOOD ( 32.10 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org Am 2021-05-06 21:18, schrieb Pratyush Yadav: > On Octal DTR capable flashes like Micron Xcella the writes cannot start > or end at an odd address in Octal DTR mode. Extra 0xff bytes need to be > appended or prepended to make sure the start address and end address > are > even. 0xff is used because on NOR flashes a program operation can only > flip bits from 1 to 0, not the other way round. 0 to 1 flip needs to > happen via erases. > > Signed-off-by: Pratyush Yadav > > --- > > drivers/mtd/spi-nor/core.c | 72 +++++++++++++++++++++++++++++++++++++- > 1 file changed, 71 insertions(+), 1 deletion(-) > > diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c > index 3d66cc34af4d..265d8b25fc7f 100644 > --- a/drivers/mtd/spi-nor/core.c > +++ b/drivers/mtd/spi-nor/core.c > @@ -2022,6 +2022,71 @@ static int spi_nor_read(struct mtd_info *mtd, > loff_t from, size_t len, > return ret; > } > > +/* > + * On Octal DTR capable flashes like Micron Xcella the writes cannot > start or > + * end at an odd address in Octal DTR mode. Extra 0xff bytes need to > be appended > + * or prepended to make sure the start address and end address are > even. 0xff is > + * used because on NOR flashes a program operation can only flip bits > from 1 to > + * 0, not the other way round. 0 to 1 flip needs to happen via erases. > + */ > +static int spi_nor_octal_dtr_write(struct spi_nor *nor, loff_t to, > size_t len, > + const u8 *buf) > +{ > + u8 *tmp_buf; > + size_t bytes_written; > + loff_t start, end; > + int ret; > + > + if (IS_ALIGNED(to, 2) && IS_ALIGNED(len, 2)) > + return spi_nor_write_data(nor, to, len, buf); > + > + tmp_buf = kmalloc(nor->page_size, GFP_KERNEL); > + if (!tmp_buf) > + return -ENOMEM; > + > + memset(tmp_buf, 0xff, nor->page_size); This could be replaced by just setting the first and the last byte to 0xff. But this might be easier to read. I am fine with both. > + > + start = round_down(to, 2); > + end = round_up(to + len, 2); > + > + memcpy(tmp_buf + (to - start), buf, len); > + > + ret = spi_nor_write_data(nor, start, end - start, tmp_buf); > + if (ret == 0) { > + ret = -EIO; > + goto out; > + } else if ? I've missed this in the other patch. > + if (ret < 0) > + goto out; > + > + /* > + * More bytes are written than actually requested, but that number > can't > + * be reported to the calling function or it will confuse its > + * calculations. Calculate how many of the _requested_ bytes were > + * written. > + */ > + bytes_written = ret; > + > + if (to != start) > + ret -= to - start; > + > + /* > + * Only account for extra bytes at the end if they were actually > + * written. For example, if for some reason the controller could only > + * complete a partial write then the adjustment for the extra bytes > at > + * the end is not needed. > + */ > + if (start + bytes_written == end) > + ret -= end - (to + len); > + > + if (ret < 0) > + ret = -EIO; can this happen? > + > +out: > + kfree(tmp_buf); > + return ret; > +} > + > /* > * Write an address range to the nor chip. Data must be written in > * FLASH_PAGESIZE chunks. The address range may be any size provided > @@ -2066,7 +2131,12 @@ static int spi_nor_write(struct mtd_info *mtd, > loff_t to, size_t len, > if (ret) > goto write_err; > > - ret = spi_nor_write_data(nor, addr, page_remain, buf + i); > + if (nor->write_proto == SNOR_PROTO_8_8_8_DTR) > + ret = spi_nor_octal_dtr_write(nor, addr, page_remain, > + buf + i); > + else > + ret = spi_nor_write_data(nor, addr, page_remain, > + buf + i); > if (ret < 0) > goto write_err; > written = ret; -michael ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/