From mboxrd@z Thu Jan 1 00:00:00 1970 From: Boris Brezillon Subject: Re: [PATCH v3 5/7] mtd: rawnand: ams-delta: Set port direction when needed Date: Thu, 16 Aug 2018 09:30:52 +0200 Message-ID: <20180816093052.2bcbf004@bbrezillon> References: <20180806222918.12644-1-jmkrzyszt@gmail.com> <20180813223448.21316-1-jmkrzyszt@gmail.com> <20180813223448.21316-6-jmkrzyszt@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180813223448.21316-6-jmkrzyszt@gmail.com> Sender: linux-kernel-owner@vger.kernel.org To: Janusz Krzysztofik Cc: Miquel Raynal , Richard Weinberger , David Woodhouse , Brian Norris , Marek Vasut , Tony Lindgren , Aaro Koskinen , Linus Walleij , linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, linux-mtd@lists.infradead.org, linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-omap@vger.kernel.org On Tue, 14 Aug 2018 00:34:46 +0200 Janusz Krzysztofik wrote: > In its current shape, the driver sets data port direction before each > byte read/write operation, even during multi-byte transfers. Improve > performance of the driver by setting the port direction only when > needed. > > This optimisation will become particularly important as soon as > planned conversion of the driver to GPIO API for data I/O will be > implemented. > > Signed-off-by: Janusz Krzysztofik > --- > drivers/mtd/nand/raw/ams-delta.c | 59 ++++++++++++++++++++++++++++++++-------- > 1 file changed, 47 insertions(+), 12 deletions(-) > > diff --git a/drivers/mtd/nand/raw/ams-delta.c b/drivers/mtd/nand/raw/ams-delta.c > index 09d6901fc94d..5f9180fe4f8b 100644 > --- a/drivers/mtd/nand/raw/ams-delta.c > +++ b/drivers/mtd/nand/raw/ams-delta.c > @@ -45,6 +45,7 @@ struct ams_delta_nand { > struct gpio_desc *gpiod_ale; > struct gpio_desc *gpiod_cle; > void __iomem *io_base; > + bool data_in; > }; > > /* > @@ -72,50 +73,83 @@ static const struct mtd_partition partition_info[] = { > .size = 3 * SZ_256K }, > }; > > -static void ams_delta_write_byte(struct mtd_info *mtd, u_char byte) > +static void ams_delta_write_next_byte(struct mtd_info *mtd, u_char byte) > { > struct nand_chip *this = mtd_to_nand(mtd); > struct ams_delta_nand *priv = nand_get_controller_data(this); > - void __iomem *io_base = priv->io_base; > > - writew(0, io_base + OMAP_MPUIO_IO_CNTL); > writew(byte, this->IO_ADDR_W); > + > gpiod_set_value(priv->gpiod_nwe, 0); > ndelay(40); > gpiod_set_value(priv->gpiod_nwe, 1); > } > > -static u_char ams_delta_read_byte(struct mtd_info *mtd) > +static void ams_delta_write_byte(struct mtd_info *mtd, u_char byte) > { > - u_char res; > struct nand_chip *this = mtd_to_nand(mtd); > struct ams_delta_nand *priv = nand_get_controller_data(this); > void __iomem *io_base = priv->io_base; > > + if (priv->data_in) { > + writew(0, io_base + OMAP_MPUIO_IO_CNTL); > + priv->data_in = false; > + } > + > + ams_delta_write_next_byte(mtd, byte); > +} I'm not a big fan of this {read,write}_byte/next_byte() approach. Can't we do something like: static void ams_delta_io_write(struct ams_delta_nand *priv, u8 data) { writew(byte, priv->nand_chip.IO_ADDR_W); gpiod_set_value(priv->gpiod_nwe, 0); ndelay(40); gpiod_set_value(priv->gpiod_nwe, 1); } static u8 ams_delta_io_read(struct ams_delta_nand *priv) { u8 res; gpiod_set_value(priv->gpiod_nre, 0); ndelay(40); res = readw(priv->nand_chip.IO_ADDR_R); gpiod_set_value(priv->gpiod_nre, 1); return res; } static void ams_delta_set_io_dir(struct ams_delta_nand *priv, bool in) { if (in == priv->data_in) return; writew(in ? ~0 : 0, priv->io_base + OMAP_MPUIO_IO_CNTL); priv->data_in = in; } static void ams_delta_write_buf(struct mtd_info *mtd, const u8 *buf, int len) { struct nand_chip *this = mtd_to_nand(mtd); struct ams_delta_nand *priv = nand_get_controller_data(this); int i; ams_delta_set_io_dir(priv, false); for (i =0; i < len; i++) ams_delta_io_write(priv, buf[i]); } static void ams_delta_write_byte(struct mtd_info *mtd, u8 byte) { ams_delta_write_buf(mtd, &byte, 1); } static void ams_delta_read_buf(struct mtd_info *mtd, u8 *buf, int len) { struct nand_chip *this = mtd_to_nand(mtd); struct ams_delta_nand *priv = nand_get_controller_data(this); int i; ams_delta_set_io_dir(priv, true); for (i = 0; i < len; i++) buf[i] = ams_delta_io_read(priv); } static u8 ams_delta_read_byte(struct mtd_info *mtd) { u8 res; ams_delta_read_buf(mtd, &res, 1); return res; }