RE: [PATCH v5 1/2] iio: adc: ad_sigma_delta: fix CS held asserted and state leaks

[Sabau, Radu bogdan]

> -----Original Message-----
> From: Radu Sabau via B4 Relay <devnull+radu.sabau.analog.com@xxxxxxxxxx>
> Sent: Wednesday, May 27, 2026 12:39 PM
> To: Lars-Peter Clausen <lars@xxxxxxxxxx>; Hennerich, Michael
> <Michael.Hennerich@xxxxxxxxxx>; Jonathan Cameron <jic23@xxxxxxxxxx>;
> David Lechner <dlechner@xxxxxxxxxxxx>; Sa, Nuno <Nuno.Sa@xxxxxxxxxx>;
> Andy Shevchenko <andy@xxxxxxxxxx>; Uwe Kleine König <u.kleine-
> koenig@xxxxxxxxxxxx>
> Cc: linux-iio@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Sabau, Radu
> bogdan <Radu.Sabau@xxxxxxxxxx>; Jonathan Cameron <jic23@xxxxxxxxxx>
> Subject: [PATCH v5 1/2] iio: adc: ad_sigma_delta: fix CS held asserted and
> state leaks
> 
> From: Radu Sabau <radu.sabau@xxxxxxxxxx>
> 
> In ad_sigma_delta_single_conversion(), set_mode(AD_SD_MODE_IDLE) and
> disable_one() were called from the out: block while keep_cs_asserted
> was still true. This caused any SPI transfer issued by those callbacks
> to carry cs_change=1, leaving CS permanently asserted after the
> conversion. Fix by moving both calls into the out_unlock: block, after
> keep_cs_asserted is cleared, matching the pattern already used in
> ad_sd_calibrate().
> 
> In the error path of ad_sd_buffer_postenable(), if an operation fails
> after set_mode(AD_SD_MODE_CONTINUOUS) has already succeeded (e.g.
> spi_offload_trigger_enable()), the device is left in continuous
> conversion mode with CS physically asserted. Additionally,
> bus_locked remaining true after spi_bus_unlock() causes subsequent
> SPI operations to call spi_sync_locked() without the bus lock actually
> held, allowing concurrent SPI access.
> 
> Fix the error path by clearing keep_cs_asserted first, then calling
> set_mode(AD_SD_MODE_IDLE) to revert the device mode and deassert CS,
> then clearing bus_locked before releasing the bus.
> 
> For devices that implement neither set_mode nor disable_one (such as
> MAX11205, which has no physical CS pin), no SPI transfer is issued
> during cleanup and the cs_change flag has no effect on any physical
> line.
> 

Fixes tag needed

Fixes: 132d44dc6966 ("iio: adc: ad_sigma_delta: Check for previous ready signals")

That commit moved keep_cs_asserted = false to the new out_unlock: label that runs
after set_mode(IDLE) and disable_one(). It also introduced the err_unlock: path in
ad_sd_buffer_postenable() without cleanup of those flags.

> Signed-off-by: Radu Sabau <radu.sabau@xxxxxxxxxx>
> ---
>  drivers/iio/adc/ad_sigma_delta.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad_sigma_delta.c
> b/drivers/iio/adc/ad_sigma_delta.c