From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Dongchun Zhu <dongchun.zhu@mediatek.com>
Cc: linus.walleij@linaro.org, bgolaszewski@baylibre.com,
mchehab@kernel.org, robh+dt@kernel.org, mark.rutland@arm.com,
sakari.ailus@linux.intel.com, drinkcat@chromium.org,
tfiga@chromium.org, matthias.bgg@gmail.com, bingbu.cao@intel.com,
srv_heupstream@mediatek.com, linux-mediatek@lists.infradead.org,
linux-arm-kernel@lists.infradead.org, sj.huang@mediatek.com,
linux-media@vger.kernel.org, devicetree@vger.kernel.org,
louis.kuo@mediatek.com, shengnan.wang@mediatek.com
Subject: Re: [V7, 2/2] media: i2c: dw9768: Add DW9768 VCM driver
Date: Tue, 9 Jun 2020 14:14:28 +0300 [thread overview]
Message-ID: <20200609111428.GH2428291@smile.fi.intel.com> (raw)
In-Reply-To: <1591674341.8804.628.camel@mhfsdcap03>
On Tue, Jun 09, 2020 at 11:45:41AM +0800, Dongchun Zhu wrote:
> On Mon, 2020-06-08 at 16:27 +0300, Andy Shevchenko wrote:
> > On Sat, Jun 06, 2020 at 02:19:18PM +0800, Dongchun Zhu wrote:
> > > On Fri, 2020-06-05 at 15:46 +0300, Andy Shevchenko wrote:
> > > > On Fri, Jun 05, 2020 at 06:54:12PM +0800, Dongchun Zhu wrote:
...
> > > > > +#define DW9768_AAC_TIME_DEFAULT 0x20
> > > >
> > > > Hex? Why not decimal?
> > > >
> > >
> > > There is one optional property 'dongwoon,aac-timing' defined in DT.
> > > I don't know whether you have noticed that.
> > >
> > > 'DW9768_AAC_TIME_DEFAULT' is the value set to AACT[5:0] register.
> > > I thought the Hex unit should be proper as it is directly written to the
> > > Hex register.
> >
> > I see. I would rather put it like (BIT(6) / 2) to show explicitly that we
> > choose half of the resolution.
> >
>
> I knew your idea.
> '(BIT(6) / 2)' may somewhat show the meaning of 'median of the total
> range of AACT[5:0]'.
>
> But this value is still very obscure relative to '0x20'.
> As I thought that simple is the best, especially for kernel upstream
> patch.
Okay, let's wait for maintainers to speak up.
...
> > > > > + for ( ; val >= 0; val -= DW9768_MOVE_STEPS) {
> > > > > + ret = dw9768_set_dac(dw9768, val);
> > > > > + if (ret) {
> > > > > + dev_err(&client->dev, "I2C write fail: %d", ret);
> > > > > + return ret;
> > > > > + }
> > > > > + usleep_range(move_delay_us, move_delay_us + 1000);
> > > > > + }
> > > >
> > > >
> > > > It will look more naturally in the multiplier kind of value.
> > > >
> > > > unsigned int steps = DIV_ROUND_UP(...);
> > > >
> > > > while (steps--) {
> > > > ...(..., steps * ..._MOVE_STEPS);
> > > > ...
> > > > }
> > > >
> > > > but double check arithmetics.
> > >
> > > The current coding style is actually updated with reference to your
> > > previous comments on DW9768 v3:
> > > https://patchwork.linuxtv.org/patch/61856/
> >
> > I understand, but can you consider to go further and see if the proposal works?
> >
>
> In fact, your suggestion is something like one another method to set DAC
> value to actuator.
> It is like there may be several solutions to a question.
>
> Yes. I just tried the new method and it works as expected.
> u32 steps = DIV_ROUND_UP(dw9768->focus->val, DW9768_MOVE_STEPS);
> while (steps--) {
> ret = dw9768_set_dac(dw9768, steps * DW9768_MOVE_STEPS);
> if (ret)
> return ret;
> usleep_range(move_delay_us, move_delay_us + 1000);
> }
>
> But from my perspective, I may prefer to the original method.
> As here what we really care is the DAC value,
> 'dw9768_set_dac(dw9768, val)' seems more simple.
OK.
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2020-06-09 11:14 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-05 10:54 [V7, 0/2] media: i2c: Add support for DW9768 VCM driver Dongchun Zhu
2020-06-05 10:54 ` [V7, 1/2] media: dt-bindings: media: i2c: Document DW9768 bindings Dongchun Zhu
2020-06-09 19:47 ` Rob Herring
2020-06-05 10:54 ` [V7, 2/2] media: i2c: dw9768: Add DW9768 VCM driver Dongchun Zhu
2020-06-05 12:14 ` Sakari Ailus
2020-06-05 13:02 ` Tomasz Figa
2020-06-05 13:37 ` Sakari Ailus
2020-06-06 6:24 ` Dongchun Zhu
2020-06-05 12:46 ` Andy Shevchenko
2020-06-05 13:10 ` Tomasz Figa
2020-06-06 6:19 ` Dongchun Zhu
2020-06-08 13:27 ` Andy Shevchenko
2020-06-09 3:45 ` Dongchun Zhu
2020-06-09 11:14 ` Andy Shevchenko [this message]
2020-06-10 12:58 ` Sakari Ailus
2020-06-05 13:44 ` Tomasz Figa
2020-06-06 6:42 ` Dongchun Zhu
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