Hi Arkadiusz,

On Fri, Jun 23, 2023 at 2:45 PM Arkadiusz Kubalewski
[off-list ref] wrote:

+/**
+ * convert_s48_to_s64 - convert 48 bit value to 64 bit value
+ * @signed_48: signed 64 bit variable storing signed 48 bit value
+ *
+ * Convert signed 48 bit value to its 64 bit representation.
+ *
+ * Return: signed 64 bit representation of signed 48 bit value.
+ */
+static s64 convert_s48_to_s64(s64 signed_48)
+{
+       return signed_48 & BIT_ULL(47) ?
+               GENMASK_ULL(63, 48) | signed_48 : signed_48;
+}

Can't you just use sign_extend64() from <linux/bitops.h>
passing bit 48 as sign bit istead of inventing this?

Yours,
Linus Walleij