linux-kernel - Re: [PATCH 13/15] iio: adc: ad4030: Enable dual data rate

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAHp75VcnE4-nMrL7HS4UeNCtb1w-kQRjkixROS4jociQJurdbA@mail.gmail.com>
Date: Sat, 30 Aug 2025 10:46:12 +0300
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Marcelo Schmitt <marcelo.schmitt@...log.com>
Cc: linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-doc@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-spi@...r.kernel.org, jic23@...nel.org, Michael.Hennerich@...log.com, 
	nuno.sa@...log.com, eblanc@...libre.com, dlechner@...libre.com, 
	andy@...nel.org, corbet@....net, robh@...nel.org, krzk+dt@...nel.org, 
	conor+dt@...nel.org, broonie@...nel.org, Jonathan.Cameron@...wei.com, 
	andriy.shevchenko@...ux.intel.com, ahaslam@...libre.com, 
	sergiu.cuciurean@...log.com, marcelo.schmitt1@...il.com
Subject: Re: [PATCH 13/15] iio: adc: ad4030: Enable dual data rate

On Sat, Aug 30, 2025 at 3:45 AM Marcelo Schmitt
<marcelo.schmitt@...log.com> wrote:
>
> Set AD4030 series device to do two data bit transitions per clock cycle per
> active lane when specified by firmware. The dual data rate (DDR) feature is
> available only for host clock mode and echo clock mode.

...

>  struct ad4030_state {

>         enum ad4030_out_mode mode;
>         enum ad4030_lane_mode lane_mode;
>         enum ad4030_clock_mode clock_mode;
> +       bool ddr;

I believe you run `pahole` each time you modify the data type like this.

>         /* offload sampling spi message */
>         struct spi_transfer offload_xfer;
>         struct spi_message offload_msg;

...

>         else
>                 offload_bpw  = data_width / (1 << st->lane_mode);

With the previous comment WRT right shift...

> +       if (st->ddr)
> +               offload_bpw  /= 2;

...this also can use right shift, but I understand that 2 is more
explicit to show the point of DDR (as "double").

...

> +       /* DDR is only valid for echo clock and host clock modes */
> +       if (ret == AD4030_ECHO_CLOCK_MODE || ret == AD4030_CLOCK_HOST_MODE) {
> +               st->ddr = device_property_read_bool(dev, "adi,dual-data-rate");
> +               reg_modes |= FIELD_PREP(AD4030_REG_MODES_MASK_DDR_MODE, st->ddr);

FIELD_MODIFY()?

> +       }

-- 
With Best Regards,
Andy Shevchenko