Re: [PATCH v3 5/7] iio: accel: kionix-kx022a: Refactor driver and add chip_info structure
From: Matti Vaittinen
Date: Tue Apr 25 2023 - 04:12:20 EST
On 4/25/23 10:24, Mehdi Djait wrote:
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.
Right. Maybe you could then have the buffer in private-data and allocate
it in buffer pre-enable? Do you think that would work?
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.
then please maybe split the line from appropriate point like:
buffer = kmalloc(data->chip_info->fifo_length *
KX022A_FIFO_SAMPLES_SIZE_BYTES, GFP_KERNEL);
+
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.
Thanks for going the extra mile :)
Yours,
-- Matti
--
Matti Vaittinen
Linux kernel developer at ROHM Semiconductors
Oulu Finland
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