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From: Andrea Merello <andrea.merello@gmail.com>
To: lars@metafoo.de, Michael.Hennerich@analog.com, jic23@kernel.org,
	knaack.h@gmx.de, pmeerw@pmeerw.net
Cc: linux-iio@vger.kernel.org, Andrea Merello <andrea.merello@gmail.com>
Subject: [PATCH 2/4] iio: ad7949: fix incorrect SPI xfer len
Date: Thu, 12 Sep 2019 16:43:08 +0200
Message-ID: <20190912144310.7458-3-andrea.merello@gmail.com> (raw)
In-Reply-To: <20190912144310.7458-1-andrea.merello@gmail.com>

This driver supports 14-bits and 16-bits devices. All of them have a 14-bit
configuration registers. All SPI trasfers, for reading AD conversion
results and for writing the configuration register, fit in two bytes.

The driver always uses 4-bytes xfers which seems at least pointless (maybe
even harmful). This patch trims the SPI xfer len and the buffer size to
two bytes.

Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
---
 drivers/iio/adc/ad7949.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/adc/ad7949.c b/drivers/iio/adc/ad7949.c
index 518044c31a73..5c2b3446fa4a 100644
--- a/drivers/iio/adc/ad7949.c
+++ b/drivers/iio/adc/ad7949.c
@@ -54,7 +54,7 @@ struct ad7949_adc_chip {
 	u8 resolution;
 	u16 cfg;
 	unsigned int current_channel;
-	u32 buffer ____cacheline_aligned;
+	u16 buffer ____cacheline_aligned;
 };
 
 static int ad7949_spi_write_cfg(struct ad7949_adc_chip *ad7949_adc, u16 val,
@@ -67,7 +67,7 @@ static int ad7949_spi_write_cfg(struct ad7949_adc_chip *ad7949_adc, u16 val,
 	struct spi_transfer tx[] = {
 		{
 			.tx_buf = &ad7949_adc->buffer,
-			.len = 4,
+			.len = 2,
 			.bits_per_word = bits_per_word,
 		},
 	};
@@ -95,7 +95,7 @@ static int ad7949_spi_read_channel(struct ad7949_adc_chip *ad7949_adc, int *val,
 	struct spi_transfer tx[] = {
 		{
 			.rx_buf = &ad7949_adc->buffer,
-			.len = 4,
+			.len = 2,
 			.bits_per_word = bits_per_word,
 		},
 	};
-- 
2.17.1


  parent reply index

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-12 14:43 [PATCH 0/4] Fixes for ad7949 Andrea Merello
2019-09-12 14:43 ` [PATCH 1/4] iio: ad7949: kill pointless "readback"-handling code Andrea Merello
2019-09-13  6:37   ` Ardelean, Alexandru
2019-09-15 10:26     ` Jonathan Cameron
2019-09-12 14:43 ` Andrea Merello [this message]
2019-09-13  6:46   ` [PATCH 2/4] iio: ad7949: fix incorrect SPI xfer len Ardelean, Alexandru
2019-09-13  7:56     ` Andrea Merello
2019-09-13  8:28       ` Ardelean, Alexandru
2019-09-15 10:36       ` Jonathan Cameron
2019-09-16  7:51         ` Ardelean, Alexandru
2019-09-21 17:16           ` Jonathan Cameron
2019-09-12 14:43 ` [PATCH 3/4] iio: ad7949: fix SPI xfer delays Andrea Merello
2019-09-13  6:59   ` Ardelean, Alexandru
2019-09-13  8:23     ` Andrea Merello
2019-09-13  8:43       ` Ardelean, Alexandru
2019-09-12 14:43 ` [PATCH 4/4] iio: ad7949: fix channels mixups Andrea Merello
2019-09-13  7:19   ` Ardelean, Alexandru
2019-09-13  8:30     ` Andrea Merello
2019-09-13 11:30       ` Couret Charles-Antoine
2019-09-13 11:40         ` Andrea Merello
2019-09-20  7:45         ` Andrea Merello
2019-09-21 17:12           ` Jonathan Cameron
2019-09-23  8:21             ` Andrea Merello
2019-10-05  9:55               ` Jonathan Cameron
     [not found]                 ` <CAN8YU5PRO5Y5EeEj2SZGm5XfuKSB1rtS7nKdu6wWxXYDOfexqw@mail.gmail.com>
2019-10-22  8:56                   ` Jonathan Cameron
2019-11-04 14:12                     ` Andrea Merello
2019-11-09 11:58                       ` Jonathan Cameron
2019-11-12 15:09                       ` Couret Charles-Antoine
2019-12-02 14:13                         ` [v2] " Andrea Merello
2019-12-02 15:36                           ` Couret Charles-Antoine
2019-12-04 11:06                             ` Jonathan Cameron
2019-12-04 11:13                               ` Couret Charles-Antoine
2019-12-06 16:45                                 ` Jonathan Cameron
2019-09-13  7:24 ` [PATCH 0/4] Fixes for ad7949 Ardelean, Alexandru
2019-09-13 14:00   ` Couret Charles-Antoine
2019-09-15 10:49     ` Jonathan Cameron
2019-09-16  7:39       ` Andrea Merello
2019-09-16  7:48         ` Ardelean, Alexandru
2019-09-16  7:50           ` Ardelean, Alexandru
2019-09-16  7:34     ` Andrea Merello

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