Re: [PATCH] iio: adc: axp288: Override TS pin bias current for some models

[Jonathan Cameron <jic23@kernel.org>]

On Sun, 15 Sep 2019 20:53:42 +0200
Hans de Goede <hdegoede@redhat.com> wrote:

> Since commit 9bcf15f75cac ("iio: adc: axp288: Fix TS-pin handling") we
> preserve the bias current set by the firmware at boot.  This fixes issues
> we were seeing on various models, but it seems our old hardcoded 80ųA bias
> current was working around a firmware bug on at least one model laptop.
> 
> In order to both have our cake and eat it, this commit adds a dmi based
> list of models where we need to override the firmware set bias current and
> adds the one model we now know needs this to it: The Lenovo Ideapad 100S
> (11 inch version).

Ouch.

> 
> Cc: stable@vger.kernel.org
> Fixes: 9bcf15f75cac ("iio: adc: axp288: Fix TS-pin handling")
> BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=203829
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Applied to the fixes-togreg branch of iio.git.

Thanks,

Jonathan

> ---
>  drivers/iio/adc/axp288_adc.c | 32 ++++++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
> 
> diff --git a/drivers/iio/adc/axp288_adc.c b/drivers/iio/adc/axp288_adc.c
> index 31d51bcc5f2c..85d08e68b34f 100644
> --- a/drivers/iio/adc/axp288_adc.c
> +++ b/drivers/iio/adc/axp288_adc.c
> @@ -7,6 +7,7 @@
>   * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>   */
>  
> +#include <linux/dmi.h>
>  #include <linux/module.h>
>  #include <linux/kernel.h>
>  #include <linux/device.h>
> @@ -25,6 +26,11 @@
>  #define AXP288_ADC_EN_MASK				0xF0
>  #define AXP288_ADC_TS_ENABLE				0x01
>  
> +#define AXP288_ADC_TS_BIAS_MASK				GENMASK(5, 4)
> +#define AXP288_ADC_TS_BIAS_20UA				(0 << 4)
> +#define AXP288_ADC_TS_BIAS_40UA				(1 << 4)
> +#define AXP288_ADC_TS_BIAS_60UA				(2 << 4)
> +#define AXP288_ADC_TS_BIAS_80UA				(3 << 4)
>  #define AXP288_ADC_TS_CURRENT_ON_OFF_MASK		GENMASK(1, 0)
>  #define AXP288_ADC_TS_CURRENT_OFF			(0 << 0)
>  #define AXP288_ADC_TS_CURRENT_ON_WHEN_CHARGING		(1 << 0)
> @@ -177,10 +183,36 @@ static int axp288_adc_read_raw(struct iio_dev *indio_dev,
>  	return ret;
>  }
>  
> +/*
> + * We rely on the machine's firmware to correctly setup the TS pin bias current
> + * at boot. This lists systems with broken fw where we need to set it ourselves.
> + */
> +static const struct dmi_system_id axp288_adc_ts_bias_override[] = {
> +	{
> +		/* Lenovo Ideapad 100S (11 inch) */
> +		.matches = {
> +		  DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
> +		  DMI_MATCH(DMI_PRODUCT_VERSION, "Lenovo ideapad 100S-11IBY"),
> +		},
> +		.driver_data = (void *)(uintptr_t)AXP288_ADC_TS_BIAS_80UA,
> +	},
> +	{}
> +};
> +
>  static int axp288_adc_initialize(struct axp288_adc_info *info)
>  {
> +	const struct dmi_system_id *bias_override;
>  	int ret, adc_enable_val;
>  
> +	bias_override = dmi_first_match(axp288_adc_ts_bias_override);
> +	if (bias_override) {
> +		ret = regmap_update_bits(info->regmap, AXP288_ADC_TS_PIN_CTRL,
> +					 AXP288_ADC_TS_BIAS_MASK,
> +					 (uintptr_t)bias_override->driver_data);
> +		if (ret)
> +			return ret;
> +	}
> +
>  	/*
>  	 * Determine if the TS pin is enabled and set the TS current-source
>  	 * accordingly.