iio: gyro: mpu3050: Fix alignment and size issues with buffers.

Fix a set of closely related issues.
1. When using fifo_values() there was not enough space for the timestamp to
   be inserted by iio_push_to_buffers_with_timestamp()
2. fifo_values() did not meet the alignment requirement of
   iio_push_to_buffers_with_timestamp()
3. hw_values did not meet the alignment requirement either.

1 and 2 fixed by using new iio_push_to_buffers_with_ts_unaligned() which has
no alignment or space padding requirements.
3 fixed by introducing a structure that makes the space and alignment
requirements explicit.

Fixes: 3904b28efb2c ("iio: gyro: Add driver for the MPU-3050 gyroscope")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20210613151039.569883-4-jic23@kernel.org

diff --git a/drivers/iio/gyro/mpu3050-core.c b/drivers/iio/gyro/mpu3050-core.c
index 3225de1f023b35fa66355fb61b49cef5504d1fa0..ea387efab62d24096b1b484ccca4dfc41ec3ed40 100644 (file)
--- a/drivers/iio/gyro/mpu3050-core.c
+++ b/drivers/iio/gyro/mpu3050-core.c
@@ -471,13 +471,10 @@ static irqreturn_t mpu3050_trigger_handler(int irq, void *p)
        struct iio_dev *indio_dev = pf->indio_dev;
        struct mpu3050 *mpu3050 = iio_priv(indio_dev);
        int ret;
-       /*
-        * Temperature 1*16 bits
-        * Three axes 3*16 bits
-        * Timestamp 64 bits (4*16 bits)
-        * Sum total 8*16 bits
-        */
-       __be16 hw_values[8];
+       struct {
+               __be16 chans[4];
+               s64 timestamp __aligned(8);
+       } scan;
        s64 timestamp;
        unsigned int datums_from_fifo = 0;
 
@@ -572,9 +569,10 @@ static irqreturn_t mpu3050_trigger_handler(int irq, void *p)
                                fifo_values[4]);
 
                        /* Index past the footer (fifo_values[0]) and push */
-                       iio_push_to_buffers_with_timestamp(indio_dev,
-                                                          &fifo_values[1],
-                                                          timestamp);
+                       iio_push_to_buffers_with_ts_unaligned(indio_dev,
+                                                             &fifo_values[1],
+                                                             sizeof(__be16) * 4,
+                                                             timestamp);
 
                        fifocnt -= toread;
                        datums_from_fifo++;
@@ -632,15 +630,15 @@ static irqreturn_t mpu3050_trigger_handler(int irq, void *p)
                goto out_trigger_unlock;
        }
 
-       ret = regmap_bulk_read(mpu3050->map, MPU3050_TEMP_H, &hw_values,
-                              sizeof(hw_values));
+       ret = regmap_bulk_read(mpu3050->map, MPU3050_TEMP_H, scan.chans,
+                              sizeof(scan.chans));
        if (ret) {
                dev_err(mpu3050->dev,
                        "error reading axis data\n");
                goto out_trigger_unlock;
        }
 
-       iio_push_to_buffers_with_timestamp(indio_dev, hw_values, timestamp);
+       iio_push_to_buffers_with_timestamp(indio_dev, &scan, timestamp);
 
 out_trigger_unlock:
        mutex_unlock(&mpu3050->lock);