linux-kernel - [PATCH 5.4 158/177] iio: ad7949: kill pointless "readback"-handling code

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 16 Dec 2019 18:50:14 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Andrea Merello <andrea.merello@...il.com>,
        Alexandru Ardelean <alexandru.ardelean@...log.com>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 158/177] iio: ad7949: kill pointless "readback"-handling code

From: Andrea Merello <andrea.merello@...il.com>

[ Upstream commit c270bbf7bb9ddc4e2a51b3c56557c377c9ac79bc ]

The device could be configured to spit out also the configuration word
while reading the AD result value (in the same SPI xfer) - this is called
"readback" in the device datasheet.

The driver checks if readback is enabled and it eventually adjusts the SPI
xfer length and it applies proper shifts to still get the data, discarding
the configuration word.

The readback option is actually never enabled (the driver disables it), so
the said checks do not serve for any purpose.

Since enabling the readback option seems not to provide any advantage (the
driver entirely sets the configuration word without relying on any default
value), just kill the said, unused, code.

Signed-off-by: Andrea Merello <andrea.merello@...il.com>
Reviewed-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/iio/adc/ad7949.c | 27 +++------------------------
 1 file changed, 3 insertions(+), 24 deletions(-)

diff --git a/drivers/iio/adc/ad7949.c b/drivers/iio/adc/ad7949.c
index ac0ffff6c5ae1..518044c31a73b 100644
--- a/drivers/iio/adc/ad7949.c
+++ b/drivers/iio/adc/ad7949.c
@@ -57,29 +57,11 @@ struct ad7949_adc_chip {
 	u32 buffer ____cacheline_aligned;
 };
 
-static bool ad7949_spi_cfg_is_read_back(struct ad7949_adc_chip *ad7949_adc)
-{
-	if (!(ad7949_adc->cfg & AD7949_CFG_READ_BACK))
-		return true;
-
-	return false;
-}
-
-static int ad7949_spi_bits_per_word(struct ad7949_adc_chip *ad7949_adc)
-{
-	int ret = ad7949_adc->resolution;
-
-	if (ad7949_spi_cfg_is_read_back(ad7949_adc))
-		ret += AD7949_CFG_REG_SIZE_BITS;
-
-	return ret;
-}
-
 static int ad7949_spi_write_cfg(struct ad7949_adc_chip *ad7949_adc, u16 val,
 				u16 mask)
 {
 	int ret;
-	int bits_per_word = ad7949_spi_bits_per_word(ad7949_adc);
+	int bits_per_word = ad7949_adc->resolution;
 	int shift = bits_per_word - AD7949_CFG_REG_SIZE_BITS;
 	struct spi_message msg;
 	struct spi_transfer tx[] = {
@@ -107,7 +89,7 @@ static int ad7949_spi_read_channel(struct ad7949_adc_chip *ad7949_adc, int *val,
 				   unsigned int channel)
 {
 	int ret;
-	int bits_per_word = ad7949_spi_bits_per_word(ad7949_adc);
+	int bits_per_word = ad7949_adc->resolution;
 	int mask = GENMASK(ad7949_adc->resolution, 0);
 	struct spi_message msg;
 	struct spi_transfer tx[] = {
@@ -138,10 +120,7 @@ static int ad7949_spi_read_channel(struct ad7949_adc_chip *ad7949_adc, int *val,
 
 	ad7949_adc->current_channel = channel;
 
-	if (ad7949_spi_cfg_is_read_back(ad7949_adc))
-		*val = (ad7949_adc->buffer >> AD7949_CFG_REG_SIZE_BITS) & mask;
-	else
-		*val = ad7949_adc->buffer & mask;
+	*val = ad7949_adc->buffer & mask;
 
 	return 0;
 }
-- 
2.20.1