linux-kernel - [BUG] device_property_read

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Date:   Fri, 14 Jan 2022 17:48:52 -0500
From:   Peter Geis <pgwipeout@...il.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [BUG] device_property_read_u16 reads out only zero

Good Evening,

I seem to have come across a strange bug with drivers/base/property.c
while expanding the new cyttsp5 driver to handle device-tree
overrides.

With the property:
touchscreen-size-x = <1863>;
The following code:
u32 test_u32 = 32; /* canary to catch writing a zero */
u16 test_u16 = 16; /* canary to catch writing a zero */
int ret;

ret = device_property_read_u32(ts->dev, "touchscreen-size-x", &test_u32);
if(ret)
dev_err(ts->dev, "read_u32 failed ret: %d\n", ret);

ret = device_property_read_u16(ts->dev, "touchscreen-size-x", &test_u16);
if(ret)
dev_err(ts->dev, "read_u16 failed ret: %d\n", ret);

dev_err(ts->dev, "read_u32: %d, read_u16: %d\n", test_u32, test_u16);

returns the following:
[    1.010876] cyttsp5 5-0024: read_u32: 1863, read_u16: 0

This was as of 5.16-rc8, using the
gcc-arm-10.2-2020.11-x86_64-aarch64-none-linux-gnu compiler.
I honestly am at a loss here, any insight you can provide here would
be appreciated.

Very Respectfully,
Peter Geis