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Message-ID: <0900650872a1533a344df375e99ce116046b3ee0.camel@gmail.com>
Date: Wed, 09 Apr 2025 07:32:09 +0100
From: Nuno Sá <noname.nuno@...il.com>
To: Angelo Dureghello <adureghello@...libre.com>, Nuno Sá
<nuno.sa@...log.com>, Jonathan Cameron <jic23@...nel.org>, Lars-Peter
Clausen <lars@...afoo.de>, Jonathan Corbet <corbet@....net>, Olivier Moysan
<olivier.moysan@...s.st.com>, Michael Hennerich
<Michael.Hennerich@...log.com>
Cc: linux-iio@...r.kernel.org, linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 5/5] iio: dac: ad3552r-hs: add support for internal
ramp
On Tue, 2025-04-08 at 12:18 +0200, Angelo Dureghello wrote:
> From: Angelo Dureghello <adureghello@...libre.com>
>
> The ad3552r can be feeded from the HDL controller by an internally
> generated 16bit ramp, useful for debug pourposes. Add debugfs a file
> to enable or disable it.
>
> Signed-off-by: Angelo Dureghello <adureghello@...libre.com>
> ---
Hi Angelo,
One issue that needs a respin and then a minor comment... With it,
Reviewed-by: Nuno Sá <nuno.sa@...log.com>
> drivers/iio/dac/ad3552r-hs.c | 166 +++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 160 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/iio/dac/ad3552r-hs.c b/drivers/iio/dac/ad3552r-hs.c
> index
> 37397e188f225a8099745ec03f7c604da76960b1..9a8eed7a06e4f2e7b23d59764b8f2fc21e2c4537
> 100644
> --- a/drivers/iio/dac/ad3552r-hs.c
> +++ b/drivers/iio/dac/ad3552r-hs.c
> @@ -7,6 +7,7 @@
> */
>
> #include <linux/bitfield.h>
> +#include <linux/debugfs.h>
> #include <linux/delay.h>
> #include <linux/gpio/consumer.h>
> #include <linux/iio/backend.h>
> @@ -54,6 +55,18 @@ struct ad3552r_hs_state {
> struct ad3552r_hs_platform_data *data;
> /* INTERFACE_CONFIG_D register cache, in DDR we cannot read values. */
> u32 config_d;
> + /* Protects backend I/O operations from concurrent accesses. */
> + struct mutex lock;
> +};
> +
> +enum ad3552r_sources {
> + AD3552R_SRC_IIO_BUFFER,
> + AD3552R_SRC_BACKEND_RAMP_GEN,
> +};
> +
> +static const char * const dbgfs_attr_source[] = {
> + [AD3552R_SRC_IIO_BUFFER] = "iio-buffer",
> + [AD3552R_SRC_BACKEND_RAMP_GEN] = "backend-ramp-generator",
> };
nit: I would use more generic strings. I assume "iio-buffer" is just the "normal"
data so use something like that. For the ramp, is it 16 bits? I would just use ex:
RAMP_16. I do not thing that the "backend" prefix (as well as "-generator") to add
much.
>
...
> +
> +static ssize_t ad3552r_hs_show_data_source_avail(struct file *f,
> + char __user *userbuf,
> + size_t count, loff_t *ppos)
> +{
> + ssize_t len = 0;
> + char *buf;
> + int i;
> +
> + buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
> + if (!buf)
> + return -ENOMEM;
> +
When are we freeing this memory? I also do not see the point for a PAGE_SIZE
allocation for such a small string table. I would say to simplify things and use a
local buffer with 64/128 bytes (should be more than enough). If you see this growing
in the future, you can also go with seq_file.
- Nuno Sá
> + for (i = 0; i < ARRAY_SIZE(dbgfs_attr_source); i++) {
> + len += scnprintf(buf + len, PAGE_SIZE - len, "%s ",
> + dbgfs_attr_source[i]);
> + }
> + buf[len - 1] = '\n';
> +
> + return simple_read_from_buffer(userbuf, count, ppos, buf, len);
> +}
> +
> +static const struct file_operations ad3552r_hs_data_source_fops = {
> + .owner = THIS_MODULE,
> + .write = ad3552r_hs_write_data_source,
> + .read = ad3552r_hs_show_data_source,
> +};
> +
> +static const struct file_operations ad3552r_hs_data_source_avail_fops = {
> + .owner = THIS_MODULE,
> + .read = ad3552r_hs_show_data_source_avail,
> +};
> +
> static int ad3552r_hs_setup(struct ad3552r_hs_state *st)
> {
> u16 id;
> @@ -550,11 +678,7 @@ static int ad3552r_hs_setup(struct ad3552r_hs_state *st)
> if (ret)
> return ret;
>
> - ret = iio_backend_data_source_set(st->back, 0, IIO_BACKEND_EXTERNAL);
> - if (ret)
> - return ret;
> -
> - ret = iio_backend_data_source_set(st->back, 1, IIO_BACKEND_EXTERNAL);
> + ret = ad3552r_hs_set_data_source(st, IIO_BACKEND_EXTERNAL);
> if (ret)
> return ret;
>
> @@ -661,6 +785,26 @@ static const struct iio_info ad3552r_hs_info = {
> .debugfs_reg_access = &ad3552r_hs_reg_access,
> };
>
> +static void ad3552r_hs_debugfs_init(struct iio_dev *indio_dev)
> +{
> + struct ad3552r_hs_state *st = iio_priv(indio_dev);
> + struct dentry *d = iio_get_debugfs_dentry(indio_dev);
> +
> + if (!IS_ENABLED(CONFIG_DEBUG_FS))
> + return;
> +
> + d = iio_get_debugfs_dentry(indio_dev);
> + if (!d) {
> + dev_warn(st->dev, "can't set debugfs in driver dir\n");
> + return;
> + }
> +
> + debugfs_create_file("data_source", 0600, d, st,
> + &ad3552r_hs_data_source_fops);
> + debugfs_create_file("data_source_available", 0600, d, st,
> + &ad3552r_hs_data_source_avail_fops);
> +}
> +
> static int ad3552r_hs_probe(struct platform_device *pdev)
> {
> struct ad3552r_hs_state *st;
> @@ -705,7 +849,17 @@ static int ad3552r_hs_probe(struct platform_device *pdev)
> if (ret)
> return ret;
>
> - return devm_iio_device_register(&pdev->dev, indio_dev);
> + ret = devm_iio_device_register(&pdev->dev, indio_dev);
> + if (ret)
> + return ret;
> +
> + ret = devm_mutex_init(&pdev->dev, &st->lock);
> + if (ret)
> + return ret;
> +
> + ad3552r_hs_debugfs_init(indio_dev);
> +
> + return ret;
> }
>
> static const struct of_device_id ad3552r_hs_of_id[] = {
>
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