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Message-ID: <20250426113527.20b2069b@jic23-huawei>
Date: Sat, 26 Apr 2025 11:35:27 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Andrew Ijano <andrew.ijano@...il.com>
Cc: andrew.lopes@...mni.usp.br, gustavobastos@....br, dlechner@...libre.com,
nuno.sa@...log.com, andy@...nel.org, jstephan@...libre.com,
linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] iio: accel: sca3000: remove duplicated code in
sca3000_read_data()
On Fri, 25 Apr 2025 20:50:51 -0300
Andrew Ijano <andrew.ijano@...il.com> wrote:
> Remove duplicated code between sca3000_read_data() and
> sca3000_read_data_short() functions.
>
> The common behavior is centralized in just one sca3000_read_data()
> function and used for every case.
>
> Signed-off-by: Andrew Ijano <andrew.lopes@...mni.usp.br>
> Co-developed-by: Gustavo Bastos <gustavobastos@....br>
> Signed-off-by: Gustavo Bastos <gustavobastos@....br>
Look at the helpers that exist for spi sequences like this.
This is an old driver so may not be making full use of newer infrastructure.
In particular a lot of these can probably become spi_w8r8()and
it may make sense to move the SCA3000_READ_REG() to the callers to avoid the
need for these helpers at all.
Note that is not an appropriate change for the large reads though as
spi_write_then_read() bounces all buffers and so would add a copy
to those high(ish) performance paths.
> ---
> drivers/iio/accel/sca3000.c | 82 ++++++++++++++-----------------------
> 1 file changed, 30 insertions(+), 52 deletions(-)
>
> diff --git a/drivers/iio/accel/sca3000.c b/drivers/iio/accel/sca3000.c
> index aabe4491efd7..c4b1da7f8de1 100644
> --- a/drivers/iio/accel/sca3000.c
> +++ b/drivers/iio/accel/sca3000.c
> @@ -281,10 +281,11 @@ static int sca3000_write_reg(struct sca3000_state *st, u8 address, u8 val)
> return spi_write(st->us, st->tx, 2);
> }
>
> -static int sca3000_read_data_short(struct sca3000_state *st,
> - u8 reg_address_high,
> - int len)
> +static int sca3000_read_data(struct sca3000_state *st,
> + u8 reg_address_high,
> + int len)
> {
> + int ret;
> struct spi_transfer xfer[2] = {
> {
> .len = 1,
> @@ -296,7 +297,10 @@ static int sca3000_read_data_short(struct sca3000_state *st,
> };
> st->tx[0] = SCA3000_READ_REG(reg_address_high);
>
> - return spi_sync_transfer(st->us, xfer, ARRAY_SIZE(xfer));
> + ret = spi_sync_transfer(st->us, xfer, ARRAY_SIZE(xfer));
> + if (ret)
> + dev_err(&st->us->dev, "problem reading register\n");
> + return ret;
> }
>
> /**
> @@ -309,7 +313,7 @@ static int sca3000_reg_lock_on(struct sca3000_state *st)
> {
> int ret;
>
> - ret = sca3000_read_data_short(st, SCA3000_REG_STATUS_ADDR, 1);
> + ret = sca3000_read_data(st, SCA3000_REG_STATUS_ADDR, 1);
As above this could be simply
ret = spi_w8r8(st->spi, SCA3000_READ_REG(SCA3000_REG_STATUS_ADDR));
if (ret)
return ret;
return !(ret & SCA3000_LOCKED);
I think...
You will want to walk through how that helper is implemented to check it
ends up doing the same thing as the existing code though and remove
st->rx as part of the conversion.
> if (ret < 0)
> return ret;
>
> @@ -412,7 +416,7 @@ static int sca3000_read_ctrl_reg(struct sca3000_state *st,
> ret = sca3000_write_reg(st, SCA3000_REG_CTRL_SEL_ADDR, ctrl_reg);
> if (ret)
> goto error_ret;
> - ret = sca3000_read_data_short(st, SCA3000_REG_CTRL_DATA_ADDR, 1);
> + ret = sca3000_read_data(st, SCA3000_REG_CTRL_DATA_ADDR, 1);
> if (ret)
> goto error_ret;
> return st->rx[0];
> @@ -432,7 +436,7 @@ static int sca3000_print_rev(struct iio_dev *indio_dev)
> struct sca3000_state *st = iio_priv(indio_dev);
>
> mutex_lock(&st->lock);
> - ret = sca3000_read_data_short(st, SCA3000_REG_REVID_ADDR, 1);
> + ret = sca3000_read_data(st, SCA3000_REG_REVID_ADDR, 1);
> if (ret < 0)
> goto error_ret;
> dev_info(&indio_dev->dev,
> @@ -575,7 +579,7 @@ static inline int __sca3000_get_base_freq(struct sca3000_state *st,
> {
> int ret;
>
> - ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
> + ret = sca3000_read_data(st, SCA3000_REG_MODE_ADDR, 1);
> if (ret)
> goto error_ret;
> switch (SCA3000_REG_MODE_MODE_MASK & st->rx[0]) {
> @@ -665,7 +669,7 @@ static int sca3000_read_3db_freq(struct sca3000_state *st, int *val)
> {
> int ret;
>
> - ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
> + ret = sca3000_read_data(st, SCA3000_REG_MODE_ADDR, 1);
> if (ret)
> return ret;
>
> @@ -703,7 +707,7 @@ static int sca3000_write_3db_freq(struct sca3000_state *st, int val)
> mode = SCA3000_REG_MODE_MEAS_MODE_OP_2;
> else
> return -EINVAL;
> - ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
> + ret = sca3000_read_data(st, SCA3000_REG_MODE_ADDR, 1);
> if (ret)
> return ret;
>
> @@ -732,7 +736,7 @@ static int sca3000_read_raw(struct iio_dev *indio_dev,
> return -EBUSY;
> }
> address = sca3000_addresses[chan->address][0];
> - ret = sca3000_read_data_short(st, address, 2);
> + ret = sca3000_read_data(st, address, 2);
> if (ret < 0) {
> mutex_unlock(&st->lock);
> return ret;
> @@ -742,7 +746,7 @@ static int sca3000_read_raw(struct iio_dev *indio_dev,
> chan->scan_type.realbits - 1);
> } else {
> /* get the temperature when available */
> - ret = sca3000_read_data_short(st,
> + ret = sca3000_read_data(st,
> SCA3000_REG_TEMP_MSB_ADDR,
> 2);
For this spi_w8r16() may be applicable.
> if (ret < 0) {
> @@ -830,7 +834,7 @@ static ssize_t sca3000_read_av_freq(struct device *dev,
> int len = 0, ret, val;
>
> mutex_lock(&st->lock);
> - ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
> + ret = sca3000_read_data(st, SCA3000_REG_MODE_ADDR, 1);
> val = st->rx[0];
> mutex_unlock(&st->lock);
> if (ret)
> @@ -969,32 +973,6 @@ static const struct attribute_group sca3000_attribute_group = {
> .attrs = sca3000_attributes,
> };
>
> -static int sca3000_read_data(struct sca3000_state *st,
> - u8 reg_address_high,
> - u8 *rx,
> - int len)
> -{
> - int ret;
> - struct spi_transfer xfer[2] = {
> - {
> - .len = 1,
> - .tx_buf = st->tx,
> - }, {
> - .len = len,
> - .rx_buf = rx,
> - }
> - };
> -
> - st->tx[0] = SCA3000_READ_REG(reg_address_high);
> - ret = spi_sync_transfer(st->us, xfer, ARRAY_SIZE(xfer));
> - if (ret) {
> - dev_err(&st->us->dev, "problem reading register\n");
> - return ret;
> - }
> -
> - return 0;
> -}
> -
> /**
> * sca3000_ring_int_process() - ring specific interrupt handling.
> * @val: Value of the interrupt status register.
> @@ -1008,7 +986,7 @@ static void sca3000_ring_int_process(u8 val, struct iio_dev *indio_dev)
> mutex_lock(&st->lock);
>
> if (val & SCA3000_REG_INT_STATUS_HALF) {
> - ret = sca3000_read_data_short(st, SCA3000_REG_BUF_COUNT_ADDR,
> + ret = sca3000_read_data(st, SCA3000_REG_BUF_COUNT_ADDR,
> 1);
> if (ret)
> goto error_ret;
> @@ -1017,7 +995,7 @@ static void sca3000_ring_int_process(u8 val, struct iio_dev *indio_dev)
> * num_available is the total number of samples available
> * i.e. number of time points * number of channels.
> */
> - ret = sca3000_read_data(st, SCA3000_REG_RING_OUT_ADDR, st->rx,
> + ret = sca3000_read_data(st, SCA3000_REG_RING_OUT_ADDR,
> num_available * 2);
This is the one case were spi_write_then_read() is probably not appropriate due to the
large buffers that are potentially involved.
I think this will be the only remaining case to use the old infrastructure.
Thanks,
Jonathan
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