From df1d80aee963480c5c2938c64ec0ac3e4a0df2e0 Mon Sep 17 00:00:00 2001 From: Lars-Peter Clausen Date: Tue, 19 Mar 2019 13:37:55 +0200 Subject: iio: ad_sigma_delta: Properly handle SPI bus locking vs CS assertion For devices from the SigmaDelta family we need to keep CS low when doing a conversion, since the device will use the MISO line as a interrupt to indicate that the conversion is complete. This is why the driver locks the SPI bus and when the SPI bus is locked keeps as long as a conversion is going on. The current implementation gets one small detail wrong though. CS is only de-asserted after the SPI bus is unlocked. This means it is possible for a different SPI device on the same bus to send a message which would be wrongfully be addressed to the SigmaDelta device as well. Make sure that the last SPI transfer that is done while holding the SPI bus lock de-asserts the CS signal. Signed-off-by: Lars-Peter Clausen Signed-off-by: Alexandru Ardelean Signed-off-by: Jonathan Cameron --- include/linux/iio/adc/ad_sigma_delta.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/iio/adc/ad_sigma_delta.h b/include/linux/iio/adc/ad_sigma_delta.h index 7e84351fa2c0..6e9fb1932dde 100644 --- a/include/linux/iio/adc/ad_sigma_delta.h +++ b/include/linux/iio/adc/ad_sigma_delta.h @@ -69,6 +69,7 @@ struct ad_sigma_delta { bool irq_dis; bool bus_locked; + bool keep_cs_asserted; uint8_t comm; -- cgit v1.3-8-gc7d7