Hi Matti,
On Tue, Apr 25, 2023 at 09:50:11AM +0300, Matti Vaittinen wrote:
> On 4/25/23 01:22, Mehdi Djait wrote:
> > Add the chip_info structure to the driver's private data to hold all
> > the device specific infos.
> > Refactor the kx022a driver implementation to make it more generic and
> > extensible.
> >
> > Signed-off-by: Mehdi Djait <mehdi.djait.k@xxxxxxxxx>
> > ---
> > v3:
> > - added the change of the buffer's allocation in the __kx022a_fifo_flush
> > to this patch
> > - added the chip_info to the struct kx022a_data
> >
> > v2:
> > - mentioned the introduction of the i2c_device_id table in the commit
> > - get i2c_/spi_get_device_id only when device get match fails
> > - removed the generic KX_define
> > - removed the kx022a_device_type enum
> > - added comments for the chip_info struct elements
> > - fixed errors pointed out by the kernel test robot
> >
> > drivers/iio/accel/kionix-kx022a-i2c.c | 15 +++-
> > drivers/iio/accel/kionix-kx022a-spi.c | 15 +++-
> > drivers/iio/accel/kionix-kx022a.c | 114 +++++++++++++++++---------
> > drivers/iio/accel/kionix-kx022a.h | 54 +++++++++++-
> > 4 files changed, 147 insertions(+), 51 deletions(-)
> >
> > diff --git a/drivers/iio/accel/kionix-kx022a-i2c.c b/drivers/iio/accel/kionix-kx022a-i2c.c
> > index 8f23631a1fd3..ce299d0446f7 100644
> > --- a/drivers/iio/accel/kionix-kx022a-i2c.c
> > +++ b/drivers/iio/accel/kionix-kx022a-i2c.c
> > @@ -15,6 +15,7 @@
>
> ...
>
>
> > static int __kx022a_fifo_flush(struct iio_dev *idev, unsigned int samples,
> > @@ -600,13 +600,17 @@ static int __kx022a_fifo_flush(struct iio_dev *idev, unsigned int samples,
> > {
> > struct kx022a_data *data = iio_priv(idev);
> > struct device *dev = regmap_get_device(data->regmap);
> > - __le16 buffer[KX022A_FIFO_LENGTH * 3];
> > + __le16 *buffer;
> > uint64_t sample_period;
> > int count, fifo_bytes;
> > bool renable = false;
> > int64_t tstamp;
> > int ret, i;
> > + buffer = kmalloc(data->chip_info->fifo_length * KX022A_FIFO_SAMPLES_SIZE_BYTES, GFP_KERNEL);
> > + if (!buffer)
> > + return -ENOMEM;
>
> Do you think we could get rid of allocating and freeing the buffer for each
> flush? I feel it is a bit wasteful, and with high sampling frequencies this
> function can be called quite often. Do you think there would be a way to
> either use stack (always reserve big enough buffer no matter which chip we
> have - or is the buffer too big to be safely taken from the stack?), or a
> buffer stored in private data and allocated at probe or buffer enable?
I tried using the same allocation as before but a device like the KX127
has a fifo_length of 342 (compared to 86 for kx132, and 43 for kx022a).
Allocating this much using the stack will result in a Warning.
>
> Also, please avoid such long lines. I know many people don't care about the
> line length - but for example I tend to have 3 terminal windows open
> side-by-side on my laptop screen. Hence long lines tend to be harder to read
> for me.
That is the case for me also, but Jonathan asked me to change
"fifo_length * 6" and the KX022A_FIFO_SAMPLES_SIZE_BYTES is already
defined.
>
> > +
> > ret = regmap_read(data->regmap, KX022A_REG_BUF_STATUS_1, &fifo_bytes);
> > if (ret) {
> > dev_err(dev, "Error reading buffer status\n");
> > @@ -621,8 +625,10 @@ static int __kx022a_fifo_flush(struct iio_dev *idev, unsigned int samples,
> > dev_warn(data->dev, "Bad FIFO alignment. Data may be corrupt\n");
> > count = fifo_bytes / KX022A_FIFO_SAMPLES_SIZE_BYTES;
> > - if (!count)
> > + if (!count) {
> > + kfree(buffer);
> > return 0;
> > + }
> > /*
> > * If we are being called from IRQ handler we know the stored timestamp
> > @@ -679,7 +685,7 @@ static int __kx022a_fifo_flush(struct iio_dev *idev, unsigned int samples,
> > }
> > fifo_bytes = count * KX022A_FIFO_SAMPLES_SIZE_BYTES;
> > - ret = regmap_noinc_read(data->regmap, KX022A_REG_BUF_READ,
> > + ret = regmap_noinc_read(data->regmap, data->chip_info->buf_read,
> > &buffer[0], fifo_bytes);
> > if (ret)
> > goto renable_out;
> > @@ -704,6 +710,7 @@ static int __kx022a_fifo_flush(struct iio_dev *idev, unsigned int samples,
> > if (renable)
> > enable_irq(data->irq);
> > + kfree(buffer);
> > return ret;
> > }
> >
> ...
>
> > -int kx022a_probe_internal(struct device *dev)
> > +const struct kx022a_chip_info kx022a_chip_info = {
> > + .name = "kx022-accel",
> > + .regmap_config = &kx022a_regmap_config,
> > + .channels = kx022a_channels,
> > + .num_channels = ARRAY_SIZE(kx022a_channels),
> > + .fifo_length = KX022A_FIFO_LENGTH,
> > + .who = KX022A_REG_WHO,
> > + .id = KX022A_ID,
> > + .cntl = KX022A_REG_CNTL,
> > + .cntl2 = KX022A_REG_CNTL2,
> > + .odcntl = KX022A_REG_ODCNTL,
> > + .buf_cntl1 = KX022A_REG_BUF_CNTL1,
> > + .buf_cntl2 = KX022A_REG_BUF_CNTL2,
> > + .buf_clear = KX022A_REG_BUF_CLEAR,
> > + .buf_status1 = KX022A_REG_BUF_STATUS_1,
> > + .buf_read = KX022A_REG_BUF_READ,
> > + .inc1 = KX022A_REG_INC1,
> > + .inc4 = KX022A_REG_INC4,
> > + .inc5 = KX022A_REG_INC5,
> > + .inc6 = KX022A_REG_INC6,
> > + .xout_l = KX022A_REG_XOUT_L,
> > +};
> > +EXPORT_SYMBOL_NS_GPL(kx022a_chip_info, IIO_KX022A);
>
> Do you think the fields (or at least some of them) in this struct could be
> named based on the (main) functionality being used, not based on the
> register name? Something like "watermark_reg", "buf_en_reg", "reset_reg",
> "output_rate_reg", "int1_pinconf_reg", "int1_src_reg", "int2_pinconf_reg",
> "int1_src_reg" ...
>
> I would not be at all surprized to see for example some IRQ control to be
> shifted from INC<X> to INC<Y> or cntl<X> / buf_cntl<X> stuff to be moved to
> cntl<Y> or to buf_cntl<Y> for next sensor we want to support. Especially
> when new cool feature is added to next sensor, resulting also adding a new
> cntl<Z> or buf_cntl<Z> or INC<Z>.
>
> I, however, believe the _functionality_ will be there (in some register) -
> at least for the ICs for which we can re-use this driver. Hence, it might be
> nice - and if you can think of better names for these fields - to rename
> them based on the _functionality_ we use.
>
> Another benefit would be added clarity to the code. Writing a value to
> "buf_en_reg", "watermark_reg" or to "int1_src_reg" is much clearer (to me)
> than writing a value to "buf_cntl1", "buf_cntl2" or "INC4". Especially if
> you don't have a datasheet at your hands.
>
> I am not "demanding" this (at least not for now :]) because it seems these
> two Kionix sensors have been pretty consistent what comes to maintaining the
> same functionality in the registers with same naming - but I believe this is
> something that may in any case be lurking around the corner.
I agree, this seems to be the better solution. I will look into this.
>
>
>
> All in all, looks nice and clean to me! Good job.
Thank you :)
--
Kind Regards
Mehdi Djait
