linux-kernel - Re: [PATCH v3 04/12] iio: accel: adxl313: make use of regmap cache

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Message-ID: <20250525132216.0bbc7067@jic23-huawei>
Date: Sun, 25 May 2025 13:22:16 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Lothar Rubusch <l.rubusch@...il.com>
Cc: dlechner@...libre.com, nuno.sa@...log.com, andy@...nel.org,
 corbet@....net, lucas.p.stankus@...il.com, lars@...afoo.de,
 Michael.Hennerich@...log.com, linux-iio@...r.kernel.org,
 linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 04/12] iio: accel: adxl313: make use of regmap cache

On Fri, 23 May 2025 22:35:15 +0000
Lothar Rubusch <l.rubusch@...il.com> wrote:

> Setup regmap cache to cache register configuration. This is a preparatory
> step for follow up patches, to allow easy acces to the cached
> configuration.

I think this stands on it's own given registers like the calibbias
are already both written and read from.  So I'd generalize the justification
to simply reducing unnecessary bus traffic.

Jonathan

> 
> Signed-off-by: Lothar Rubusch <l.rubusch@...il.com>
> ---
>  drivers/iio/accel/adxl313.h      |  2 ++
>  drivers/iio/accel/adxl313_core.c | 17 +++++++++++++++++
>  drivers/iio/accel/adxl313_i2c.c  |  6 ++++++
>  drivers/iio/accel/adxl313_spi.c  |  6 ++++++
>  4 files changed, 31 insertions(+)
> 
> diff --git a/drivers/iio/accel/adxl313.h b/drivers/iio/accel/adxl313.h
> index 72f624af4686..fc937bdf83b6 100644
> --- a/drivers/iio/accel/adxl313.h
> +++ b/drivers/iio/accel/adxl313.h
> @@ -54,6 +54,8 @@ extern const struct regmap_access_table adxl312_writable_regs_table;
>  extern const struct regmap_access_table adxl313_writable_regs_table;
>  extern const struct regmap_access_table adxl314_writable_regs_table;
>  
> +bool adxl313_is_volatile_reg(struct device *dev, unsigned int reg);
> +
>  enum adxl313_device_type {
>  	ADXL312,
>  	ADXL313,
> diff --git a/drivers/iio/accel/adxl313_core.c b/drivers/iio/accel/adxl313_core.c
> index 06a771bb4726..0c893c286017 100644
> --- a/drivers/iio/accel/adxl313_core.c
> +++ b/drivers/iio/accel/adxl313_core.c
> @@ -46,6 +46,23 @@ const struct regmap_access_table adxl314_readable_regs_table = {
>  };
>  EXPORT_SYMBOL_NS_GPL(adxl314_readable_regs_table, IIO_ADXL313);
>  
> +bool adxl313_is_volatile_reg(struct device *dev, unsigned int reg)
> +{
> +	switch (reg) {
> +	case ADXL313_REG_DATA_AXIS(0):
> +	case ADXL313_REG_DATA_AXIS(1):
> +	case ADXL313_REG_DATA_AXIS(2):
> +	case ADXL313_REG_DATA_AXIS(3):
> +	case ADXL313_REG_DATA_AXIS(4):
> +	case ADXL313_REG_DATA_AXIS(5):
> +	case ADXL313_REG_FIFO_STATUS:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +EXPORT_SYMBOL_NS_GPL(adxl313_is_volatile_reg, "IIO_ADXL313");
> +
>  static int adxl312_check_id(struct device *dev,
>  			    struct adxl313_data *data)
>  {
> diff --git a/drivers/iio/accel/adxl313_i2c.c b/drivers/iio/accel/adxl313_i2c.c
> index a4cf0cf2c5aa..e8636e8ab14f 100644
> --- a/drivers/iio/accel/adxl313_i2c.c
> +++ b/drivers/iio/accel/adxl313_i2c.c
> @@ -21,6 +21,8 @@ static const struct regmap_config adxl31x_i2c_regmap_config[] = {
>  		.rd_table	= &adxl312_readable_regs_table,
>  		.wr_table	= &adxl312_writable_regs_table,
>  		.max_register	= 0x39,
> +		.volatile_reg	= adxl313_is_volatile_reg,
> +		.cache_type	= REGCACHE_MAPLE,
>  	},
>  	[ADXL313] = {
>  		.reg_bits	= 8,
> @@ -28,6 +30,8 @@ static const struct regmap_config adxl31x_i2c_regmap_config[] = {
>  		.rd_table	= &adxl313_readable_regs_table,
>  		.wr_table	= &adxl313_writable_regs_table,
>  		.max_register	= 0x39,
> +		.volatile_reg	= adxl313_is_volatile_reg,
> +		.cache_type	= REGCACHE_MAPLE,
>  	},
>  	[ADXL314] = {
>  		.reg_bits	= 8,
> @@ -35,6 +39,8 @@ static const struct regmap_config adxl31x_i2c_regmap_config[] = {
>  		.rd_table	= &adxl314_readable_regs_table,
>  		.wr_table	= &adxl314_writable_regs_table,
>  		.max_register	= 0x39,
> +		.volatile_reg	= adxl313_is_volatile_reg,
> +		.cache_type	= REGCACHE_MAPLE,
>  	},
>  };
>  
> diff --git a/drivers/iio/accel/adxl313_spi.c b/drivers/iio/accel/adxl313_spi.c
> index 9a16b40bff34..68e323e81aeb 100644
> --- a/drivers/iio/accel/adxl313_spi.c
> +++ b/drivers/iio/accel/adxl313_spi.c
> @@ -24,6 +24,8 @@ static const struct regmap_config adxl31x_spi_regmap_config[] = {
>  		.max_register	= 0x39,
>  		/* Setting bits 7 and 6 enables multiple-byte read */
>  		.read_flag_mask	= BIT(7) | BIT(6),
> +		.volatile_reg	= adxl313_is_volatile_reg,
> +		.cache_type	= REGCACHE_MAPLE,
>  	},
>  	[ADXL313] = {
>  		.reg_bits	= 8,
> @@ -33,6 +35,8 @@ static const struct regmap_config adxl31x_spi_regmap_config[] = {
>  		.max_register	= 0x39,
>  		/* Setting bits 7 and 6 enables multiple-byte read */
>  		.read_flag_mask	= BIT(7) | BIT(6),
> +		.volatile_reg	= adxl313_is_volatile_reg,
> +		.cache_type	= REGCACHE_MAPLE,
>  	},
>  	[ADXL314] = {
>  		.reg_bits	= 8,
> @@ -42,6 +46,8 @@ static const struct regmap_config adxl31x_spi_regmap_config[] = {
>  		.max_register	= 0x39,
>  		/* Setting bits 7 and 6 enables multiple-byte read */
>  		.read_flag_mask	= BIT(7) | BIT(6),
> +		.volatile_reg	= adxl313_is_volatile_reg,
> +		.cache_type	= REGCACHE_MAPLE,
>  	},
>  };
>