Re: [PATCH 3/7] ath9k: Add support for reading the EEPROM data using the nvmem API

Christian Lamparter
2017-03-13T23:53:59Z

On Monday, March 13, 2017 10:05:11 PM CET Alban wrote:
> Currently SoC platforms use a firmware request to get the EEPROM data.
> This is mostly a hack and rely on using a user-helper scripts which is
> deprecated. A nicer alternative is to use the nvmem API which was
> designed for this kind of task.
>
> Furthermore we let CONFIG_ATH9K_AHB select CONFIG_NVMEM as such
> devices will generally use this method for loading the EEPROM data.
>
> Signed-off-by: Alban <albeu@free.fr>
> ---
> @@ -654,6 +656,25 @@ static int ath9k_init_softc(u16 devid, struct ath_softc *sc,
> if (ret)
> return ret;
>
> + /* If the EEPROM hasn't been retrieved via firmware request
> + * use the nvmem API insted.
> + */
> + if (!ah->eeprom_blob) {
> + struct nvmem_cell *eeprom_cell;
> +
> + eeprom_cell = nvmem_cell_get(ah->dev, "eeprom");
> + if (!IS_ERR(eeprom_cell)) {
> + ah->eeprom_data = nvmem_cell_read(
> + eeprom_cell, &ah->eeprom_size);
> + nvmem_cell_put(eeprom_cell);
> +
> + if (IS_ERR(ah->eeprom_data)) {
> + dev_err(ah->dev, "failed to read eeprom");
> + return PTR_ERR(ah->eeprom_data);
> + }
> + }
> + }
> +
> if (ath9k_led_active_high != -1)
> ah->config.led_active_high = ath9k_led_active_high == 1;
>
Are you sure this works with AR93XX SoCs that have the calibration data
in the OTP?

I've added Chris to the CC, since he has a HiveAP 121 that has this
configuration, so he can test, whenever this is a problem or not.

But from what I can tell, devices with the calibration data in the
OTP would fail now. This is because the OTP is done by ath9k_hw_init()
which hasn't run yet (it's a bit further down the road in the same
function though).

Note: the OTP doesn't store the whole caldata. Just a few parts.
A temporary "eeprom" gets constructed with the help of the
ar9300_eep_templates in ar9003_eeprom.c's
ar9300_eeprom_restore_internal(). But from what I don't think,
that the eeprom_blob is constructed/set by the functions in
ar9003_eeprom.

I think this will require an additional property like
qca,calibration-in-otp. What's your opinion?

Thanks,
Christian