linux-kernel - Re: [PATCH v2 1/1] iio: adc: meson: add separate config for axg SoC family

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Date:   Fri, 1 Dec 2023 18:08:11 +0000
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     George Stark <gnstark@...utedevices.com>
CC:     Jonathan Cameron <jic23@...nel.org>, <lars@...afoo.de>,
        <neil.armstrong@...aro.org>, <khilman@...libre.com>,
        <jbrunet@...libre.com>, <martin.blumenstingl@...glemail.com>,
        <andriy.shevchenko@...ux.intel.com>, <nuno.sa@...log.com>,
        <u.kleine-koenig@...gutronix.de>, <linux-iio@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-amlogic@...ts.infradead.org>, <kernel@...utedevices.com>
Subject: Re: [PATCH v2 1/1] iio: adc: meson: add separate config for axg SoC
 family

On Mon, 27 Nov 2023 22:17:33 +0300
George Stark <gnstark@...utedevices.com> wrote:

> Hello Jonathan
> 
> Thanks for the review.
> 
> On 11/25/23 20:25, Jonathan Cameron wrote:
> > On Wed, 22 Nov 2023 10:47:41 +0300
> > George Stark <gnstark@...utedevices.com> wrote:
> >   
> >> According to Amlogic custom kernels ADC of axg SoC family has
> >> vref_select and requires this setting to work nominally and thus
> >> needs a separate config.
> >>
> >> Signed-off-by: George Stark <gnstark@...utedevices.com>
> >> Reviewed-by: Neil Armstrong <neil.armstrong@...aro.org>  
> > 
> > Is this a fix?  If so, please provide a fixes tag.  
> Actually yes, these changes could be done in the patch that introduced
> new configuration parameters.
> 
> > Or is it aligning with the vendor kernels and we don't know if
> > it's strictly necessary or not?  
> I do know it's necessary if we want kernel driver to be independent from 
> ADC initialization in vendor u-boot code. I have Amlogic a113x device 
> (axg family) and can provide test results w and w/o this patch.

Definitely best to not rely on firmware. 

So send a Fixes tag for this and I'll apply it as a fix
(you get to figure out which patch it fixed :)

Jonathan

> 
> >   
> >> ---
> >>   drivers/iio/adc/meson_saradc.c | 16 +++++++++++++++-
> >>   1 file changed, 15 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/iio/adc/meson_saradc.c b/drivers/iio/adc/meson_saradc.c
> >> index db280da9edbf..34555a85f131 100644
> >> --- a/drivers/iio/adc/meson_saradc.c
> >> +++ b/drivers/iio/adc/meson_saradc.c
> >> @@ -1242,6 +1242,20 @@ static const struct meson_sar_adc_param meson_sar_adc_gxl_param = {
> >>   	.cmv_select = 1,
> >>   };
> >>   
> >> +static const struct meson_sar_adc_param meson_sar_adc_axg_param = {
> >> +	.has_bl30_integration = true,
> >> +	.clock_rate = 1200000,
> >> +	.bandgap_reg = MESON_SAR_ADC_REG11,
> >> +	.regmap_config = &meson_sar_adc_regmap_config_gxbb,
> >> +	.resolution = 12,
> >> +	.disable_ring_counter = 1,
> >> +	.has_reg11 = true,
> >> +	.vref_volatge = 1,
> >> +	.has_vref_select = true,
> >> +	.vref_select = VREF_VDDA,
> >> +	.cmv_select = 1,
> >> +};
> >> +
> >>   static const struct meson_sar_adc_param meson_sar_adc_g12a_param = {
> >>   	.has_bl30_integration = false,
> >>   	.clock_rate = 1200000,
> >> @@ -1286,7 +1300,7 @@ static const struct meson_sar_adc_data meson_sar_adc_gxm_data = {
> >>   };
> >>   
> >>   static const struct meson_sar_adc_data meson_sar_adc_axg_data = {
> >> -	.param = &meson_sar_adc_gxl_param,
> >> +	.param = &meson_sar_adc_axg_param,
> >>   	.name = "meson-axg-saradc",
> >>   };
> >>     
> >   
>