Re: [PATCH v2 6/8] iio: dac: ds4424: fix -128 rejection and refactor raw access
From: Andy Shevchenko <hidden>
Date: 2026-01-27 10:42:31
Also in:
linux-iio, lkml, stable
On Tue, Jan 27, 2026 at 07:09:37AM +0100, Oleksij Rempel wrote:
The DS442x DAC uses sign-magnitude encoding, so -128 cannot be represented. Previously, passing -128 resulted in a truncated value that programmed 0mA. Fix this by validating the input against the 7-bit magnitude limit. Additionally, refactor the raw access logic to use symmetrical bitwise operations, replacing the union structure.
Fixes: d632a2bd8ffc ("iio: dac: ds4422/ds4424 dac driver")Usually fixes go first in the series... ...
+#define DS4424_DAC_MASK GENMASK(6, 0) +#define DS4424_DAC_SOURCE BIT(7)
+ bits.h ? ...
case IIO_CHAN_INFO_RAW: - if (val < S8_MIN || val > S8_MAX) + abs_val = abs(val);
+
Redundant blank line.
+ if (abs_val > DS4424_DAC_MASK) return -EINVAL;
...
+ /* + * Currents exiting the IC (Source) are positive. + * Canonicalize 0 to sink; datasheet treats sign as don't-care. + */ + if (val > 0) + abs_val |= DS4424_DAC_SOURCE;
Hmm... Maybe 0 should be excluded as invalid? -- With Best Regards, Andy Shevchenko