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

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Message-ID: <20170323154328.4bb5db44@avionic-0020>
Date:   Thu, 23 Mar 2017 15:43:28 +0100
From:   Alban <albeu@...e.fr>
To:     Christian Lamparter <chunkeey@...glemail.com>
Cc:     Alban <albeu@...e.fr>,
        QCA ath9k Development <ath9k-devel@....qualcomm.com>,
        John Crispin <john@...ozen.org>,
        Kalle Valo <kvalo@...eaurora.org>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, chrisrblake93@...il.com
Subject: Re: [PATCH 3/7] ath9k: Add support for reading the EEPROM data
 using the nvmem API

On Tue, 14 Mar 2017 00:53:55 +0100
Christian Lamparter <chunkeey@...glemail.com> wrote:

> 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@...e.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 only tested this on an ar9132 platform, so it might well be that a
few things are missing for the newer SoC. However this shouldn't break
anything existing as a platform needs to define an nvmem cell on the
athk9 device for this code to be used at all.

Alban

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