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SubjectRe: [RFC PATCH 4/8] mtd: rawnand: ams-delta: Optimize pointer resolution on read/write
On Thu, 19 Jul 2018 01:57:06 +0200
Janusz Krzysztofik <jmkrzyszt@gmail.com> wrote:

> Further optimize processing speed of read/write callback functions by
> resolving private structure pointer only once per callback and passing
> it to all subfunctions instead of mtd_info.

Not sure this has a real impact on perfs, but I also prefer not using
mtd_info objects within NAND drivers, so I'm good with the change
itself (its probably worth changing the commit message though)

>
> Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
> ---
> drivers/mtd/nand/raw/ams-delta.c | 44 +++++++++++++++++++++++-----------------
> 1 file changed, 25 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/ams-delta.c b/drivers/mtd/nand/raw/ams-delta.c
> index dfefcd79b420..d7e4c9dbef67 100644
> --- a/drivers/mtd/nand/raw/ams-delta.c
> +++ b/drivers/mtd/nand/raw/ams-delta.c
> @@ -72,10 +72,9 @@ static const struct mtd_partition partition_info[] = {
> .size = 3 * SZ_256K },
> };
>
> -static void ams_delta_write_next_byte(struct mtd_info *mtd, u_char byte)
> +static void ams_delta_write_next_byte(struct ams_delta_nand *priv, u_char byte)
> {
> - struct nand_chip *this = mtd_to_nand(mtd);
> - struct ams_delta_nand *priv = nand_get_controller_data(this);
> + struct nand_chip *this = &priv->nand_chip;
>
> writew(byte, this->IO_ADDR_W);
> gpiod_set_value(priv->gpiod_nwe, 0);
> @@ -83,21 +82,18 @@ static void ams_delta_write_next_byte(struct mtd_info *mtd, u_char byte)
> gpiod_set_value(priv->gpiod_nwe, 1);
> }
>
> -static void ams_delta_write_byte(struct mtd_info *mtd, u_char byte)
> +static void ams_delta_write_first_byte(struct ams_delta_nand *priv, 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);
>
> - ams_delta_write_next_byte(mtd, byte);
> + ams_delta_write_next_byte(priv, byte);
> }
>
> -static u_char ams_delta_read_next_byte(struct mtd_info *mtd)
> +static u_char ams_delta_read_next_byte(struct ams_delta_nand *priv)
> {
> - struct nand_chip *this = mtd_to_nand(mtd);
> - struct ams_delta_nand *priv = nand_get_controller_data(this);
> + struct nand_chip *this = &priv->nand_chip;
> u_char res;
>
> gpiod_set_value(priv->gpiod_nre, 0);
> @@ -108,36 +104,46 @@ static u_char ams_delta_read_next_byte(struct mtd_info *mtd)
> return res;
> }
>
> -static u_char ams_delta_read_byte(struct mtd_info *mtd)
> +static u_char ams_delta_read_first_byte(struct ams_delta_nand *priv)
> {
> - 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);
>
> - return ams_delta_read_next_byte(mtd);
> + return ams_delta_read_next_byte(priv);
> +}
> +
> +static u_char ams_delta_read_byte(struct mtd_info *mtd)
> +{
> + struct nand_chip *this = mtd_to_nand(mtd);
> + struct ams_delta_nand *priv = nand_get_controller_data(this);
> +
> + return ams_delta_read_first_byte(priv);
> }
>
> static void ams_delta_write_buf(struct mtd_info *mtd, const u_char *buf,
> int len)
> {
> + struct nand_chip *this = mtd_to_nand(mtd);
> + struct ams_delta_nand *priv = nand_get_controller_data(this);
> int i;
>
> if (len > 0)
> - ams_delta_write_byte(mtd, buf[0]);
> + ams_delta_write_first_byte(priv, buf[0]);
> for (i = 1; i < len; i++)
> - ams_delta_write_next_byte(mtd, buf[i]);
> + ams_delta_write_next_byte(priv, buf[i]);
> }
>
> static void ams_delta_read_buf(struct mtd_info *mtd, u_char *buf, int len)
> {
> + struct nand_chip *this = mtd_to_nand(mtd);
> + struct ams_delta_nand *priv = nand_get_controller_data(this);
> int i;
>
> if (len > 0)
> - buf[0] = ams_delta_read_byte(mtd);
> + buf[0] = ams_delta_read_first_byte(priv);
> for (i = 1; i < len; i++)
> - buf[i] = ams_delta_read_next_byte(mtd);
> + buf[i] = ams_delta_read_next_byte(priv);
> }
>
> /*
> @@ -161,7 +167,7 @@ static void ams_delta_hwcontrol(struct mtd_info *mtd, int cmd,
> }
>
> if (cmd != NAND_CMD_NONE)
> - ams_delta_write_byte(mtd, cmd);
> + ams_delta_write_first_byte(priv, cmd);
> }
>
> static int ams_delta_nand_ready(struct mtd_info *mtd)

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