6.6-stable review patch. If anyone has any objections, please let me know.
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From: Valek Andrej andrej.v@skyrain.eu
commit c92c1bc408e9e11ae3c7011b062fdd74c09283a3 upstream.
There is an race-condition where device is not full working after SW reset. Therefore it's necessary to wait some time after reset and verify shadow registers values by reading and comparing the values before/after reset. This mechanism is described in datasheet at least from revision D.
Fixes: 12ed27863ea3 ("iio: accel: Add driver support for ADXL355") Signed-off-by: Valek Andrej andrej.v@skyrain.eu Signed-off-by: Kessler Markus markus.kessler@hilti.com Cc: Stable@vger.kernel.org Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/iio/accel/adxl355_core.c | 44 ++++++++++++++++++++++++++++++++++----- 1 file changed, 39 insertions(+), 5 deletions(-)
--- a/drivers/iio/accel/adxl355_core.c +++ b/drivers/iio/accel/adxl355_core.c @@ -56,6 +56,8 @@ #define ADXL355_POWER_CTL_DRDY_MSK BIT(2) #define ADXL355_SELF_TEST_REG 0x2E #define ADXL355_RESET_REG 0x2F +#define ADXL355_BASE_ADDR_SHADOW_REG 0x50 +#define ADXL355_SHADOW_REG_COUNT 5
#define ADXL355_DEVID_AD_VAL 0xAD #define ADXL355_DEVID_MST_VAL 0x1D @@ -294,7 +296,12 @@ static void adxl355_fill_3db_frequency_t static int adxl355_setup(struct adxl355_data *data) { unsigned int regval; + int retries = 5; /* the number is chosen based on empirical reasons */ int ret; + u8 *shadow_regs __free(kfree) = kzalloc(ADXL355_SHADOW_REG_COUNT, GFP_KERNEL); + + if (!shadow_regs) + return -ENOMEM;
ret = regmap_read(data->regmap, ADXL355_DEVID_AD_REG, ®val); if (ret) @@ -321,14 +328,41 @@ static int adxl355_setup(struct adxl355_ if (regval != ADXL355_PARTID_VAL) dev_warn(data->dev, "Invalid DEV ID 0x%02x\n", regval);
- /* - * Perform a software reset to make sure the device is in a consistent - * state after start-up. - */ - ret = regmap_write(data->regmap, ADXL355_RESET_REG, ADXL355_RESET_CODE); + /* Read shadow registers to be compared after reset */ + ret = regmap_bulk_read(data->regmap, + ADXL355_BASE_ADDR_SHADOW_REG, + shadow_regs, ADXL355_SHADOW_REG_COUNT); if (ret) return ret;
+ do { + if (--retries == 0) { + dev_err(data->dev, "Shadow registers mismatch\n"); + return -EIO; + } + + /* + * Perform a software reset to make sure the device is in a consistent + * state after start-up. + */ + ret = regmap_write(data->regmap, ADXL355_RESET_REG, + ADXL355_RESET_CODE); + if (ret) + return ret; + + /* Wait at least 5ms after software reset */ + usleep_range(5000, 10000); + + /* Read shadow registers for comparison */ + ret = regmap_bulk_read(data->regmap, + ADXL355_BASE_ADDR_SHADOW_REG, + data->buffer.buf, + ADXL355_SHADOW_REG_COUNT); + if (ret) + return ret; + } while (memcmp(shadow_regs, data->buffer.buf, + ADXL355_SHADOW_REG_COUNT)); + ret = regmap_update_bits(data->regmap, ADXL355_POWER_CTL_REG, ADXL355_POWER_CTL_DRDY_MSK, FIELD_PREP(ADXL355_POWER_CTL_DRDY_MSK, 1));