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Message-ID: <CA+U=DsrBMd6LmdO_gq3MT21eO2HoO0mbkZjbig600EJ=d4Q3kg@mail.gmail.com>
Date: Fri, 5 Feb 2021 11:17:04 +0200
From: Alexandru Ardelean <ardeleanalex@...il.com>
To: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Cc: Alexandru Ardelean <alexandru.ardelean@...log.com>,
LKML <linux-kernel@...r.kernel.org>,
linux-iio <linux-iio@...r.kernel.org>,
Lars-Peter Clausen <lars@...afoo.de>,
"Hennerich, Michael" <Michael.Hennerich@...log.com>,
Jonathan Cameron <jic23@...nel.org>,
Nuno Sá <nuno.sa@...log.com>,
"Bogdan, Dragos" <dragos.bogdan@...log.com>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH v3 08/11] iio: buffer: wrap all buffer attributes into iio_dev_attr
On Thu, Feb 4, 2021 at 8:26 PM Jonathan Cameron
<Jonathan.Cameron@...wei.com> wrote:
>
> On Mon, 1 Feb 2021 16:51:02 +0200
> Alexandru Ardelean <alexandru.ardelean@...log.com> wrote:
>
> > This change wraps all buffer attributes into iio_dev_attr objects, and
> > assigns a reference to the IIO buffer they belong to.
> >
> > With the addition of multiple IIO buffers per one IIO device, we need a way
> > to know which IIO buffer is being enabled/disabled/controlled.
> >
> > We know that all buffer attributes are device_attributes. So we can wrap
> > them with a iio_dev_attr types. In the iio_dev_attr type, we can also hold
> > a reference to an IIO buffer.
> > So, we end up being able to allocate wrapped attributes for all buffer
> > attributes (even the one from other drivers).
> >
> > The neat part with this mechanism, is that we don't need to add any extra
> > cleanup, because these attributes are being added to a dynamic list that
> > will get cleaned up via iio_free_chan_devattr_list().
>
>
> >
> > With this change, the 'buffer->scan_el_dev_attr_list' list is being renamed
> > to 'buffer->buffer_attr_list', effectively merging (or finalizing the
> > merge) of the buffer/ & scan_elements/ attributes internally.
> >
> > Accessing these new buffer attributes can now be done via
> > 'to_iio_dev_attr(attr)->buffer' inside the show/store handlers.
>
> That is going to look a bit odd in any drivers that use it given they
> will appear to not be embedded.
>
> There seem to be very few such attributes from a quick grep, so maybe
> we may want to unwind this and change all the types. Might still need
> to set .buffer for some of them though (only applying to new drivers as
> clearly current ones don't care!)
>
> Looking at what they actually are, some perhaps shouldn't have been in the buffer
> directory in the first place (with hindsight!).
>
> Anyhow, aside from that oddity this looks good to me.
I'm a little vague here.
If there is a suggestion for a change, I may have missed it.
I'm a bit vague on the part of "we may want to unwind this and change
all the types"
Is it referring to something like this patch?
https://lore.kernel.org/linux-iio/20210122162529.84978-10-alexandru.ardelean@analog.com/
We could do a show/store version that takes an iio_buf_attr or
iio_dev_attr parameter.
But maybe at a later point?
I don't feel it adds much benefit over the current usage of
buffer->attrs, because we need to kmalloc these iio_dev_attr anyways
to store the reference to the iio_buffer.
I would have liked to get rid of these user/external buffer->attrs.
That would have made things easier.
But, it looks like there are several drivers using them.
I usually find them by grepping for iio_triggered_buffer_setup_ext
It's only 5 drivers that provide these attributes.
It used to be a bit easier to find them by grepping
iio_buffer_set_attrs(), but I removed that.
>
> Jonathan
>
> >
> > Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
> > ---
> > drivers/iio/industrialio-buffer.c | 66 +++++++++++++++++++++----------
> > include/linux/iio/buffer_impl.h | 4 +-
> > 2 files changed, 48 insertions(+), 22 deletions(-)
> >
> > diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
> > index a525e88b302f..49996bed5f4c 100644
> > --- a/drivers/iio/industrialio-buffer.c
> > +++ b/drivers/iio/industrialio-buffer.c
> > @@ -448,7 +448,7 @@ static int iio_buffer_add_channel_sysfs(struct iio_dev *indio_dev,
> > IIO_SEPARATE,
> > &indio_dev->dev,
> > buffer,
> > - &buffer->scan_el_dev_attr_list);
> > + &buffer->buffer_attr_list);
> > if (ret)
> > return ret;
> > attrcount++;
> > @@ -460,7 +460,7 @@ static int iio_buffer_add_channel_sysfs(struct iio_dev *indio_dev,
> > 0,
> > &indio_dev->dev,
> > buffer,
> > - &buffer->scan_el_dev_attr_list);
> > + &buffer->buffer_attr_list);
> > if (ret)
> > return ret;
> > attrcount++;
> > @@ -473,7 +473,7 @@ static int iio_buffer_add_channel_sysfs(struct iio_dev *indio_dev,
> > 0,
> > &indio_dev->dev,
> > buffer,
> > - &buffer->scan_el_dev_attr_list);
> > + &buffer->buffer_attr_list);
> > else
> > ret = __iio_add_chan_devattr("en",
> > chan,
> > @@ -483,7 +483,7 @@ static int iio_buffer_add_channel_sysfs(struct iio_dev *indio_dev,
> > 0,
> > &indio_dev->dev,
> > buffer,
> > - &buffer->scan_el_dev_attr_list);
> > + &buffer->buffer_attr_list);
> > if (ret)
> > return ret;
> > attrcount++;
> > @@ -495,8 +495,7 @@ static ssize_t iio_buffer_read_length(struct device *dev,
> > struct device_attribute *attr,
> > char *buf)
> > {
> > - struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> > - struct iio_buffer *buffer = indio_dev->buffer;
> > + struct iio_buffer *buffer = to_iio_dev_attr(attr)->buffer;
> >
> > return sprintf(buf, "%d\n", buffer->length);
> > }
> > @@ -506,7 +505,7 @@ static ssize_t iio_buffer_write_length(struct device *dev,
> > const char *buf, size_t len)
> > {
> > struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> > - struct iio_buffer *buffer = indio_dev->buffer;
> > + struct iio_buffer *buffer = to_iio_dev_attr(attr)->buffer;
> > unsigned int val;
> > int ret;
> >
> > @@ -538,8 +537,7 @@ static ssize_t iio_buffer_show_enable(struct device *dev,
> > struct device_attribute *attr,
> > char *buf)
> > {
> > - struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> > - struct iio_buffer *buffer = indio_dev->buffer;
> > + struct iio_buffer *buffer = to_iio_dev_attr(attr)->buffer;
> >
> > return sprintf(buf, "%d\n", iio_buffer_is_active(buffer));
> > }
> > @@ -1154,7 +1152,7 @@ static ssize_t iio_buffer_store_enable(struct device *dev,
> > int ret;
> > bool requested_state;
> > struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> > - struct iio_buffer *buffer = indio_dev->buffer;
> > + struct iio_buffer *buffer = to_iio_dev_attr(attr)->buffer;
> > bool inlist;
> >
> > ret = strtobool(buf, &requested_state);
> > @@ -1185,8 +1183,7 @@ static ssize_t iio_buffer_show_watermark(struct device *dev,
> > struct device_attribute *attr,
> > char *buf)
> > {
> > - struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> > - struct iio_buffer *buffer = indio_dev->buffer;
> > + struct iio_buffer *buffer = to_iio_dev_attr(attr)->buffer;
> >
> > return sprintf(buf, "%u\n", buffer->watermark);
> > }
> > @@ -1197,7 +1194,7 @@ static ssize_t iio_buffer_store_watermark(struct device *dev,
> > size_t len)
> > {
> > struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> > - struct iio_buffer *buffer = indio_dev->buffer;
> > + struct iio_buffer *buffer = to_iio_dev_attr(attr)->buffer;
> > unsigned int val;
> > int ret;
> >
> > @@ -1230,8 +1227,7 @@ static ssize_t iio_dma_show_data_available(struct device *dev,
> > struct device_attribute *attr,
> > char *buf)
> > {
> > - struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> > - struct iio_buffer *buffer = indio_dev->buffer;
> > + struct iio_buffer *buffer = to_iio_dev_attr(attr)->buffer;
> >
> > return sprintf(buf, "%zu\n", iio_buffer_data_available(buffer));
> > }
> > @@ -1256,6 +1252,26 @@ static struct attribute *iio_buffer_attrs[] = {
> > &dev_attr_data_available.attr,
> > };
> >
> > +#define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr)
> > +
> > +static struct attribute *iio_buffer_wrap_attr(struct iio_buffer *buffer,
> > + struct attribute *attr)
> > +{
> > + struct device_attribute *dattr = to_dev_attr(attr);
> > + struct iio_dev_attr *iio_attr;
> > +
> > + iio_attr = kzalloc(sizeof(*iio_attr), GFP_KERNEL);
> > + if (!iio_attr)
> > + return NULL;
> > +
> > + iio_attr->buffer = buffer;
> > + memcpy(&iio_attr->dev_attr, dattr, sizeof(iio_attr->dev_attr));
> > +
> > + list_add(&iio_attr->l, &buffer->buffer_attr_list);
> > +
> > + return &iio_attr->dev_attr.attr;
> > +}
> > +
> > static int iio_buffer_register_legacy_sysfs_groups(struct iio_dev *indio_dev,
> > struct attribute **buffer_attrs,
> > int buffer_attrcount,
> > @@ -1331,7 +1347,7 @@ static int __iio_buffer_alloc_sysfs_and_mask(struct iio_buffer *buffer,
> > }
> >
> > scan_el_attrcount = 0;
> > - INIT_LIST_HEAD(&buffer->scan_el_dev_attr_list);
> > + INIT_LIST_HEAD(&buffer->buffer_attr_list);
> > channels = indio_dev->channels;
> > if (channels) {
> > /* new magic */
> > @@ -1378,9 +1394,19 @@ static int __iio_buffer_alloc_sysfs_and_mask(struct iio_buffer *buffer,
> >
> > buffer_attrcount += ARRAY_SIZE(iio_buffer_attrs);
> >
> > - attrn = buffer_attrcount;
> > + for (i = 0; i < buffer_attrcount; i++) {
> > + struct attribute *wrapped;
> > +
> > + wrapped = iio_buffer_wrap_attr(buffer, attr[i]);
> > + if (!wrapped) {
> > + ret = -ENOMEM;
> > + goto error_free_scan_mask;
> > + }
> > + attr[i] = wrapped;
> > + }
> >
> > - list_for_each_entry(p, &buffer->scan_el_dev_attr_list, l)
> > + attrn = 0;
> > + list_for_each_entry(p, &buffer->buffer_attr_list, l)
> > attr[attrn++] = &p->dev_attr.attr;
> >
> > buffer->buffer_group.name = kasprintf(GFP_KERNEL, "buffer%d", index);
> > @@ -1412,7 +1438,7 @@ static int __iio_buffer_alloc_sysfs_and_mask(struct iio_buffer *buffer,
> > error_free_scan_mask:
> > bitmap_free(buffer->scan_mask);
> > error_cleanup_dynamic:
> > - iio_free_chan_devattr_list(&buffer->scan_el_dev_attr_list);
> > + iio_free_chan_devattr_list(&buffer->buffer_attr_list);
> >
> > return ret;
> > }
> > @@ -1443,7 +1469,7 @@ static void __iio_buffer_free_sysfs_and_mask(struct iio_buffer *buffer)
> > bitmap_free(buffer->scan_mask);
> > kfree(buffer->buffer_group.name);
> > kfree(buffer->buffer_group.attrs);
> > - iio_free_chan_devattr_list(&buffer->scan_el_dev_attr_list);
> > + iio_free_chan_devattr_list(&buffer->buffer_attr_list);
> > }
> >
> > void iio_buffer_free_sysfs_and_mask(struct iio_dev *indio_dev)
> > diff --git a/include/linux/iio/buffer_impl.h b/include/linux/iio/buffer_impl.h
> > index 3e555e58475b..41044320e581 100644
> > --- a/include/linux/iio/buffer_impl.h
> > +++ b/include/linux/iio/buffer_impl.h
> > @@ -97,8 +97,8 @@ struct iio_buffer {
> > /* @scan_timestamp: Does the scan mode include a timestamp. */
> > bool scan_timestamp;
> >
> > - /* @scan_el_dev_attr_list: List of scan element related attributes. */
> > - struct list_head scan_el_dev_attr_list;
> > + /* @buffer_attr_list: List of buffer attributes. */
> > + struct list_head buffer_attr_list;
> >
> > /*
> > * @buffer_group: Attributes of the new buffer group.
>
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