linux-kernel - Re: [PATCH V2 3/3] iio: adc: Add support for PMIC7 ADC

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Date:   Mon, 27 Apr 2020 16:28:13 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Jishnu Prakash <jprakash@...eaurora.org>
Cc:     agross@...nel.org, Bjorn Andersson <bjorn.andersson@...aro.org>,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Matthias Kaehlcke <mka@...omium.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        smohanad@...eaurora.org, kgunda@...eaurora.org,
        aghayal@...eaurora.org, Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        linux-arm-msm@...r.kernel.org,
        linux-iio <linux-iio@...r.kernel.org>,
        linux-arm-msm-owner@...r.kernel.org
Subject: Re: [PATCH V2 3/3] iio: adc: Add support for PMIC7 ADC

On Mon, Apr 27, 2020 at 3:56 PM Jishnu Prakash <jprakash@...eaurora.org> wrote:
> On 4/17/2020 3:51 PM, Andy Shevchenko wrote:
> On Thu, Apr 16, 2020 at 1:48 AM Jishnu Prakash <jprakash@...eaurora.org> wrote:

Stop using HTML. It breaks badly the reply and discussion.

...

> +static const struct adc5_data adc7_data_pmic;
>
> Global variable? Hmm...
>
> adc7_data_pmic is referenced twice before its actual definition (which was added along with corresponding adc5_data struct for PMIC5 ADC), so I have given the initial declaration here.

Maybe you can realize how to avoid global variable at all?

...

> +       buf[1] &= 0xff & ~ADC5_USR_FAST_AVG_CTL_SAMPLES_MASK;
>
> What the point of 0xff & part?
>
> This was something you suggested in my first post:
>
> > +       buf[1] &= (u8) ~ADC5_USR_FAST_AVG_CTL_SAMPLES_MASK;
>
> Use '0xFF ^ _MASK' instead of casting.
>
> ...
>
> > +       buf[3] &= (u8) ~ADC5_USR_HW_SETTLE_DELAY_MASK;
>
> Ditto.
>
> I think "0xff &" works as intended here in place of casting to (u8)...

Does it work without casting? (Note, I suggested slightly different expression)
I.o.w. what the problem casting solves?

> +       buf[1] |= prop->avg_samples;
> +
> +       /* Select ADC channel */
> +       buf[2] = prop->channel;
> +
> +       /* Select HW settle delay for channel */
> +       buf[3] &= 0xff & ~ADC5_USR_HW_SETTLE_DELAY_MASK;
>
> Ditto.
>
> +       buf[3] |= prop->hw_settle_time;


-- 
With Best Regards,
Andy Shevchenko