Hi dee Ho again Jonathan (and all),
On 02/03/2025 05:46, Jonathan Cameron wrote:
On Mon, 24 Feb 2025 20:34:01 +0200
Matti Vaittinen <mazziesaccount@xxxxxxxxx> wrote:
Device pointer is the only variable which is used by the
ads7924_get_channels_config() and which is declared outside this
function. Still, the function gets the iio_device and i2c_client as
parameters. The sole caller of this function (probe) already has the
device pointer which it can directly pass to the function.
Simplify code by passing the device pointer directly as a parameter
instead of digging it from the iio_device's private data.
Signed-off-by: Matti Vaittinen <mazziesaccount@xxxxxxxxx>
Looking again at this function it doesn't seem to be doing anything
useful at all. It checks the channel nodes are in range, but
does nothing with that data. I'd just drop it entirely.
Ah. I see David suggested the same.
We can't really 'fix' what this was perhaps intended to do now
as what it does has become ABI :(
I took another look at this.
The logic in the ads7924 driver (without this patch) is actually:
ads7924_get_channels_config(...)
{
device_for_each_child_node(dev, node) {
if (fwnode_property_read_u32(node, "reg", &pval)) ..
continue;
if (channel >= ADS7924_CHANNELS)
continue;
num_channels++;
}
if (!num_channels)
return -EINVAL;
}
...
ads7924_probe()
{
ret = ads7924_get_channels_config(...);
if (ret < 0)
return dev_err_probe(...);
}
So, it still returns an error, if no channels with valid 'reg' property
were found from the DT. It will also fail the probe().
Thus, this change is not quite as likely to cause things to break as it
seemed. Still, for now anything with even single valid 'channel' has
been Ok, even if all the rest were garbage. This new variant would fail
if any of the 'channel' nodes contained no or bad 'reg'. Thus this can
still break things.
Anyways, I'll follow your suggestion and drop this patch (unless you
have second thoughts) - but I will keep the function so it still
requires at least 1 valid channel node to be found.
Yours,
-- Matti
