linux-kernel - Re: [PATCH 1/3] regulator: s2mps11: Refactor setting ramp delay

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Date:	Tue, 27 May 2014 11:56:39 +0530
From:	Yadwinder Singh Brar <yadi.brar01@...il.com>
To:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
Cc:	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>,
	Sangbeom Kim <sbkim73@...sung.com>,
	Lee Jones <lee.jones@...aro.org>,
	Sachin Kamat <sachin.kamat@...aro.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	linux-samsung-soc <linux-samsung-soc@...r.kernel.org>,
	Tomasz Figa <t.figa@...sung.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	devicetree <devicetree@...r.kernel.org>
Subject: Re: [PATCH 1/3] regulator: s2mps11: Refactor setting ramp delay

Hi Krzysztof,


On Mon, May 26, 2014 at 6:50 PM, Krzysztof Kozlowski
<k.kozlowski@...sung.com> wrote:
> Prepare for merging the s2mpa01 regulator driver into s2mps11 by:
> 1. Adding common id for buck regulators.
> 2. Splitting shared ramp delay settings to match S2MPA01.
> 3. Adding a configuration of registers for setting ramp delay for each
>    buck regulator.
>
> The functionality of the driver should not change as this patch only
> prepares for supporting S2MPA01 device.
>
> Signed-off-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>
> ---
>  drivers/regulator/s2mps11.c | 210 ++++++++++++++++++++++++++++++--------------
>  1 file changed, 144 insertions(+), 66 deletions(-)
>

[snip]

>
> -               if (ramp_delay > s2mps11->ramp_delay34)
> -                       s2mps11->ramp_delay34 = ramp_delay;
> +               if (ramp_delay > s2mps11->ramp_delay3)
> +                       s2mps11->ramp_delay3 = ramp_delay;
>                 else
> -                       ramp_delay = s2mps11->ramp_delay34;
> -
> -               ramp_shift = S2MPS11_BUCK34_RAMP_SHIFT;
> -               ramp_reg = S2MPS11_REG_RAMP;
> +                       ramp_delay = s2mps11->ramp_delay3;
>                 break;
>         case S2MPS11_BUCK4:
> -               enable_shift = S2MPS11_BUCK4_RAMP_EN_SHIFT;
>                 if (!ramp_delay) {
>                         ramp_enable = 0;
>                         break;
>                 }
>
> -               if (ramp_delay > s2mps11->ramp_delay34)
> -                       s2mps11->ramp_delay34 = ramp_delay;
> +               if (ramp_delay > s2mps11->ramp_delay4)
> +                       s2mps11->ramp_delay4 = ramp_delay;
>                 else
> -                       ramp_delay = s2mps11->ramp_delay34;
> -
> -               ramp_shift = S2MPS11_BUCK34_RAMP_SHIFT;
> -               ramp_reg = S2MPS11_REG_RAMP;
> +                       ramp_delay = s2mps11->ramp_delay4;

Main rationale behind shared value is completely omitted here, in
other cases also,
after just giving a NOTE in documentation asking user to make sure to
pass same value.
It doesn't seem safe, simply leaving a scope of stability issue (in
case ramp_delay3 > ramp_delay4).

Regards,
Yadwinder
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