Re: [PATCH 05/11] ALSA: hda/cs35l56: Create sysfs files for factory calibration

Takashi Iwai
2025-10-16T11:01:44Z

On Thu, 16 Oct 2025 12:42:36 +0200,
Richard Fitzgerald wrote:
>
> Create sysfs files that can be used to perform factory calibration.
>
> During manufacture, the production line must perform a factory calibration
> of the amps. This patch adds this functionality via sysfs files.
>
> Sysfs is used here to restrict access to the factory calibration.
> It is only intended to be used during manufacture. It is not something
> that a normal user should ever touch. Calibration affects the matching of
> the amp hardware to the external speakers. If not done correctly it can
> cause the speakers to be under-protected.
>
> As this is only needed during manufacture, there is no need for this to be
> available in a normal system so a Kconfig item has been added to enable
> this. The new Kconfig option is inside a sub-menu because items do not
> group and indent if the parent is invisible or there are multiple parent
> dependencies. Anyway the sub-menu reduces the clutter.
>
> cs35l56_hda_apply_calibration() has been changed to return an error code
> that can be reported back through the sysfs write. The original call to
> this function doesn't check the return code because in normal use it
> doesn't matter whether this fails - the firmware will default to a safe
> calibration for the platform. But tooling using sysfs might want to know
> if there was an error.
>
> Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>

What kind of data format should be written to calibrate sysfs entry?
Since those are no trivial files, we may need to document the
formats.

Also, the scenario isn't clear -- who should write this sysfs at which
moment? e.g. is this supposed to be set up at each boot?

thanks,

Takashi

> ---
> sound/hda/codecs/side-codecs/Kconfig | 15 +++
> sound/hda/codecs/side-codecs/cs35l56_hda.c | 139 ++++++++++++++++++++-
> 2 files changed, 149 insertions(+), 5 deletions(-)
>
> diff --git a/sound/hda/codecs/side-codecs/Kconfig b/sound/hda/codecs/side-codecs/Kconfig
> index cbf1847896bc..0218aa41bba2 100644
> --- a/sound/hda/codecs/side-codecs/Kconfig
> +++ b/sound/hda/codecs/side-codecs/Kconfig
> @@ -88,6 +88,21 @@ config SND_HDA_SCODEC_CS35L56_SPI
> Say Y or M here to include CS35L56 amplifier support with
> SPI control.
>
> +menu "CS35L56 driver options"
> + depends on SND_HDA_SCODEC_CS35L56
> +
> +config SND_HDA_SCODEC_CS35L56_CAL_SYSFS
> + bool "CS35L56 create sysfs for factory calibration"
> + default N
> + select SND_SOC_CS35L56_CAL_SYSFS_COMMON
> + help
> + Create sysfs entries used during factory-line manufacture
> + for factory calibration.
> + This is not needed for normal use.
> +
> + If unsure select "N".
> +endmenu
> +
> config SND_HDA_SCODEC_TAS2781
> tristate
> select SND_HDA_GENERIC
> diff --git a/sound/hda/codecs/side-codecs/cs35l56_hda.c b/sound/hda/codecs/side-codecs/cs35l56_hda.c
> index 5bb1c4ebeaf3..4a1bd934887a 100644
> --- a/sound/hda/codecs/side-codecs/cs35l56_hda.c
> +++ b/sound/hda/codecs/side-codecs/cs35l56_hda.c
> @@ -548,20 +548,24 @@ static void cs35l56_hda_release_firmware_files(const struct firmware *wmfw_firmw
> kfree(coeff_filename);
> }
>
> -static void cs35l56_hda_apply_calibration(struct cs35l56_hda *cs35l56)
> +static int cs35l56_hda_apply_calibration(struct cs35l56_hda *cs35l56)
> {
> int ret;
>
> if (!cs35l56->base.cal_data_valid || cs35l56->base.secured)
> - return;
> + return -EACCES;
>
> ret = cs_amp_write_cal_coeffs(&cs35l56->cs_dsp,
> &cs35l56_calibration_controls,
> &cs35l56->base.cal_data);
> - if (ret < 0)
> + if (ret < 0) {
> dev_warn(cs35l56->base.dev, "Failed to write calibration: %d\n", ret);
> - else
> - dev_info(cs35l56->base.dev, "Calibration applied\n");
> + return ret;
> + }
> +
> + dev_info(cs35l56->base.dev, "Calibration applied\n");
> +
> + return 0;
> }
>
> static void cs35l56_hda_fw_load(struct cs35l56_hda *cs35l56)
> @@ -669,7 +673,9 @@ static void cs35l56_hda_fw_load(struct cs35l56_hda *cs35l56)
> if (ret)
> dev_dbg(cs35l56->base.dev, "%s: cs_dsp_run ret %d\n", __func__, ret);
>
> + /* Don't need to check return code, it's not fatal if this fails */
> cs35l56_hda_apply_calibration(cs35l56);
> +
> ret = cs35l56_mbox_send(&cs35l56->base, CS35L56_MBOX_CMD_AUDIO_REINIT);
> if (ret)
> cs_dsp_stop(&cs35l56->cs_dsp);
> @@ -695,6 +701,126 @@ static void cs35l56_hda_dsp_work(struct work_struct *work)
> cs35l56_hda_fw_load(cs35l56);
> }
>
> +static ssize_t calibrate_store(struct device *dev, struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct cs35l56_hda *cs35l56 = dev_get_drvdata(dev);
> + ssize_t ret;
> +
> + ret = pm_runtime_resume_and_get(cs35l56->base.dev);
> + if (ret)
> + return ret;
> +
> + ret = cs35l56_calibrate_sysfs_store(&cs35l56->base, buf, count);
> + pm_runtime_autosuspend(cs35l56->base.dev);
> +
> + return ret;
> +}
> +
> +static ssize_t cal_temperature_store(struct device *dev, struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct cs35l56_hda *cs35l56 = dev_get_drvdata(dev);
> + ssize_t ret;
> +
> + ret = pm_runtime_resume_and_get(cs35l56->base.dev);
> + if (ret)
> + return ret;
> +
> + ret = cs35l56_cal_ambient_sysfs_store(&cs35l56->base, buf, count);
> + pm_runtime_autosuspend(cs35l56->base.dev);
> +
> + return ret;
> +}
> +
> +static ssize_t cal_data_read(struct file *filp, struct kobject *kobj,
> + const struct bin_attribute *battr, char *buf, loff_t pos,
> + size_t count)
> +{
> + struct cs35l56_hda *cs35l56 = dev_get_drvdata(kobj_to_dev(kobj));
> + ssize_t ret;
> +
> + ret = pm_runtime_resume_and_get(cs35l56->base.dev);
> + if (ret)
> + return ret;
> +
> + ret = cs35l56_cal_data_sysfs_read(&cs35l56->base, buf, pos, count);
> + pm_runtime_autosuspend(cs35l56->base.dev);
> +
> + return ret;
> +}
> +
> +static ssize_t cal_data_write(struct file *filp, struct kobject *kobj,
> + const struct bin_attribute *battr, char *buf, loff_t pos,
> + size_t count)
> +{
> + struct cs35l56_hda *cs35l56 = dev_get_drvdata(kobj_to_dev(kobj));
> + ssize_t ret;
> +
> + ret = cs35l56_cal_data_sysfs_write(&cs35l56->base, buf, pos, count);
> + if (ret == -ENODATA)
> + return count; /* Ignore writes of empty cal blobs */
> +
> + if (ret < 0)
> + return ret;
> +
> + ret = pm_runtime_resume_and_get(cs35l56->base.dev);
> + if (ret)
> + return ret;
> +
> + ret = cs35l56_hda_apply_calibration(cs35l56);
> + if (ret == 0)
> + cs35l56_mbox_send(&cs35l56->base, CS35L56_MBOX_CMD_AUDIO_REINIT);
> + else
> + count = -EIO;
> +
> + pm_runtime_autosuspend(cs35l56->base.dev);
> +
> + return count;
> +}
> +
> +static const DEVICE_ATTR_WO(calibrate);
> +static const DEVICE_ATTR_WO(cal_temperature);
> +static const BIN_ATTR_RW(cal_data, sizeof_field(struct cs35l56_base, cal_data));
> +
> +static const struct attribute *cs35l56_hda_cal_attributes[] = {
> + &dev_attr_calibrate.attr,
> + &dev_attr_cal_temperature.attr,
> + NULL
> +};
> +
> +static void cs35l56_hda_create_calibration_sysfs(struct cs35l56_hda *cs35l56)
> +{
> + struct device *dev = cs35l56->base.dev;
> + int ret;
> +
> + if (!IS_ENABLED(CONFIG_SND_HDA_SCODEC_CS35L56_CAL_SYSFS))
> + return;
> +
> + ret = sysfs_create_files(&dev->kobj, cs35l56_hda_cal_attributes);
> + if (ret)
> + goto err;
> +
> + ret = sysfs_create_bin_file(&dev->kobj, &bin_attr_cal_data);
> + if (ret)
> + goto err;
> +
> + return;
> +err:
> + dev_err_probe(dev, ret, "Failed creating calibration sysfs\n");
> +}
> +
> +static void cs35l56_hda_remove_calibration_sysfs(struct cs35l56_hda *cs35l56)
> +{
> + struct device *dev = cs35l56->base.dev;
> +
> + if (!IS_ENABLED(CONFIG_SND_HDA_SCODEC_CS35L56_CAL_SYSFS))
> + return;
> +
> + sysfs_remove_files(&dev->kobj, cs35l56_hda_cal_attributes);
> + sysfs_remove_bin_file(&dev->kobj, &bin_attr_cal_data);
> +}
> +
> static int cs35l56_hda_bind(struct device *dev, struct device *master, void *master_data)
> {
> struct cs35l56_hda *cs35l56 = dev_get_drvdata(dev);
> @@ -722,6 +848,8 @@ static int cs35l56_hda_bind(struct device *dev, struct device *master, void *mas
> cs_dsp_init_debugfs(&cs35l56->cs_dsp, cs35l56->debugfs_root);
> #endif
>
> + cs35l56_hda_create_calibration_sysfs(cs35l56);
> +
> dev_dbg(cs35l56->base.dev, "Bound\n");
>
> return 0;
> @@ -736,6 +864,7 @@ static void cs35l56_hda_unbind(struct device *dev, struct device *master, void *
> cancel_work_sync(&cs35l56->dsp_work);
>
> cs35l56_hda_remove_controls(cs35l56);
> + cs35l56_hda_remove_calibration_sysfs(cs35l56);
>
> #if IS_ENABLED(CONFIG_SND_DEBUG)
> cs_dsp_cleanup_debugfs(&cs35l56->cs_dsp);
> --
> 2.47.3
>