Re: [PATCH v3 5/7] iio: accel: kionix-kx022a: Refactor driver and add chip_info structure
From: Matti Vaittinen
Date: Sat Apr 29 2023 - 09:56:50 EST
On 4/29/23 15:59, Mehdi Djait wrote:
Hi Matti,
On Tue, Apr 25, 2023 at 11:12:11AM +0300, Matti Vaittinen wrote:
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?
Do you mean add a new function kx022a_buffer_preenable to iio_buffer_setup_ops ?
Sorry. I thought the kx022a already implemented the pre-enable callback
but it was the postenable. I was mistaken.
Would adding the allocation to kx022a_fifo_enable and the free to
kx022a_fifo_disable be a good option also ?
Yes. I think that should work!
Yours,
-- Matti
--
Matti Vaittinen
Linux kernel developer at ROHM Semiconductors
Oulu Finland
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