Mask the value read before returning it. The value read over the parallel bus via the AXI ADC IP block contains both the address and the data, but callers expect val to only contain the data.
axi_adc_raw_write() takes a u32 parameter, so addr was the wrong type. This wasn't causing any issues but is corrected anyway since we are touching the same line to add a new variable.
Cc: stable@vger.kernel.org Fixes: 79c47485e438 ("iio: adc: adi-axi-adc: add support for AD7606 register writing") Signed-off-by: David Lechner dlechner@baylibre.com --- Changes in v2: - Use ADI_AXI_REG_VALUE_MASK instead of hard-coding 0xFF. - Introduce local variable and use FIELD_PREP() instead of modifying val. - Link to v1: https://lore.kernel.org/r/20250530-iio-adc-adi-axi-adc-fix-ad7606_bus_reg_re... --- drivers/iio/adc/adi-axi-adc.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/iio/adc/adi-axi-adc.c b/drivers/iio/adc/adi-axi-adc.c index cf942c043457ccea49207c3900153ee371b3774f..fc745297bcb82cf2cf7f30c7fcf9bba2d861a48c 100644 --- a/drivers/iio/adc/adi-axi-adc.c +++ b/drivers/iio/adc/adi-axi-adc.c @@ -445,7 +445,7 @@ static int axi_adc_raw_read(struct iio_backend *back, u32 *val) static int ad7606_bus_reg_read(struct iio_backend *back, u32 reg, u32 *val) { struct adi_axi_adc_state *st = iio_backend_get_priv(back); - int addr; + u32 addr, reg_val;
guard(mutex)(&st->lock);
@@ -455,7 +455,9 @@ static int ad7606_bus_reg_read(struct iio_backend *back, u32 reg, u32 *val) */ addr = FIELD_PREP(ADI_AXI_REG_ADDRESS_MASK, reg) | ADI_AXI_REG_READ_BIT; axi_adc_raw_write(back, addr); - axi_adc_raw_read(back, val); + axi_adc_raw_read(back, ®_val); + + *val = FIELD_GET(ADI_AXI_REG_VALUE_MASK, reg_val);
/* Write 0x0 on the bus to get back to ADC mode */ axi_adc_raw_write(back, 0);
--- base-commit: 7cdfbc0113d087348b8e65dd79276d0f57b89a10 change-id: 20250530-iio-adc-adi-axi-adc-fix-ad7606_bus_reg_read-f2bbb503db8b
Best regards,
On Fri, 30 May 2025 16:50:14 -0500 David Lechner dlechner@baylibre.com wrote:
Mask the value read before returning it. The value read over the parallel bus via the AXI ADC IP block contains both the address and the data, but callers expect val to only contain the data.
axi_adc_raw_write() takes a u32 parameter, so addr was the wrong type. This wasn't causing any issues but is corrected anyway since we are touching the same line to add a new variable.
Cc: stable@vger.kernel.org Fixes: 79c47485e438 ("iio: adc: adi-axi-adc: add support for AD7606 register writing") Signed-off-by: David Lechner dlechner@baylibre.com
I've applied this to my temporary fixes-togreg-for-6.16 branch for now. That will get rebased on rc1 once available. As such I'm fine adding tags or indeed dropping it again if others have feedback!
Jonathan
Changes in v2:
- Use ADI_AXI_REG_VALUE_MASK instead of hard-coding 0xFF.
- Introduce local variable and use FIELD_PREP() instead of modifying val.
- Link to v1: https://lore.kernel.org/r/20250530-iio-adc-adi-axi-adc-fix-ad7606_bus_reg_re...
drivers/iio/adc/adi-axi-adc.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/iio/adc/adi-axi-adc.c b/drivers/iio/adc/adi-axi-adc.c index cf942c043457ccea49207c3900153ee371b3774f..fc745297bcb82cf2cf7f30c7fcf9bba2d861a48c 100644 --- a/drivers/iio/adc/adi-axi-adc.c +++ b/drivers/iio/adc/adi-axi-adc.c @@ -445,7 +445,7 @@ static int axi_adc_raw_read(struct iio_backend *back, u32 *val) static int ad7606_bus_reg_read(struct iio_backend *back, u32 reg, u32 *val) { struct adi_axi_adc_state *st = iio_backend_get_priv(back);
- int addr;
- u32 addr, reg_val;
guard(mutex)(&st->lock); @@ -455,7 +455,9 @@ static int ad7606_bus_reg_read(struct iio_backend *back, u32 reg, u32 *val) */ addr = FIELD_PREP(ADI_AXI_REG_ADDRESS_MASK, reg) | ADI_AXI_REG_READ_BIT; axi_adc_raw_write(back, addr);
- axi_adc_raw_read(back, val);
- axi_adc_raw_read(back, ®_val);
- *val = FIELD_GET(ADI_AXI_REG_VALUE_MASK, reg_val);
/* Write 0x0 on the bus to get back to ADC mode */ axi_adc_raw_write(back, 0);
base-commit: 7cdfbc0113d087348b8e65dd79276d0f57b89a10 change-id: 20250530-iio-adc-adi-axi-adc-fix-ad7606_bus_reg_read-f2bbb503db8b
Best regards,
linux-stable-mirror@lists.linaro.org
-
David Lechner -
Jonathan Cameron