linux-kernel - Re: [PATCH v4 1/3] drm/panel: refactor INNOLUX P079ZCA panel driver

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Date:   Thu, 15 Mar 2018 10:35:10 +0800
From:   hl <hl@...k-chips.com>
To:     Emil Velikov <emil.l.velikov@...il.com>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Brian Norris <briannorris@...omium.org>,
        Rob Herring <robh+dt@...nel.org>,
        Sean Paul <seanpaul@...omium.org>,
        David Airlie <airlied@...ux.ie>,
        "Linux-Kernel@...r. Kernel. Org" <linux-kernel@...r.kernel.org>,
        ML dri-devel <dri-devel@...ts.freedesktop.org>
Subject: Re: [PATCH v4 1/3] drm/panel: refactor INNOLUX P079ZCA panel driver

Hi Emil,


On Wednesday, March 14, 2018 08:02 PM, Emil Velikov wrote:
> Hi Lin,
>
> On 14 March 2018 at 09:12, Lin Huang <hl@...k-chips.com> wrote:
>> From: huang lin <hl@...k-chips.com>
>>
>> Refactor Innolux P079ZCA panel driver, let it support
>> multi panel.
>>
>> Change-Id: If89be5e56dba8cb498e2d50c1bbeb0e8016123a2
>> Signed-off-by: Lin Huang <hl@...k-chips.com>
>> ---
>> Changes in v2:
>> - Change regulator property name to meet the panel datasheet
>> Changes in v3:
>> - this patch only refactor P079ZCA panel to support multi panel, support P097PFG panel in another patch
>> Changes in v4:
>> - Modify the patch which suggest by Thierry
>>
> Thanks for splitting this up. I think there's another piece that fell
> through the cracks.
> I'm not deeply familiar with the driver, so just sharing some quick notes.
>
>
>>   struct innolux_panel {
>>          struct drm_panel base;
>>          struct mipi_dsi_device *link;
>> +       const struct panel_desc *desc;
>>
>>          struct backlight_device *backlight;
>> -       struct regulator *supply;
>> +       struct regulator *vddi;
>> +       struct regulator *avdd;
>> +       struct regulator *avee;
> These two seem are new addition, as opposed to a dummy refactor.
> Are they optional, does one need them for the existing panel (separate
> patch?) or only for the new one (squash with the new panel code)?
>
>
>>          struct gpio_desc *enable_gpio;
>>
>>          bool prepared;
>> @@ -77,9 +93,9 @@ static int innolux_panel_unprepare(struct drm_panel *panel)
>>          /* T8: 80ms - 1000ms */
>>          msleep(80);
>>
>> -       err = regulator_disable(innolux->supply);
>> -       if (err < 0)
>> -               return err;
> Good call on dropping the early return here.
>
>
>> @@ -207,19 +248,28 @@ static const struct drm_panel_funcs innolux_panel_funcs = {
>> -       innolux->supply = devm_regulator_get(dev, "power");
>> -       if (IS_ERR(innolux->supply))
>> -               return PTR_ERR(innolux->supply);
>> +       innolux = devm_kzalloc(dev, sizeof(*innolux), GFP_KERNEL);
>> +       if (!innolux)
>> +               return -ENOMEM;
>> +
>> +       innolux->desc = desc;
>> +       innolux->vddi = devm_regulator_get(dev, "power");
>> +       innolux->avdd = devm_regulator_get(dev, "avdd");
>> +       innolux->avee = devm_regulator_get(dev, "avee");
>>
> AFAICT devm_regulator_get returns a pointer which is unsuitable to be
> passed into regulator_{enable,disable}.
> Hence, the IS_ERR check should stay. If any of the regulators are
> optional, you want to call regulator_{enable,disable} only as
> applicable.

devm_regulator_get() will use dummy_regulator if there not regulator pass to driver,
so it not affect regulator_{enable, disable}. These three regulator are optional,
the p079zca will use "power" and p097pgf will use "avdd" and "avee",
so i think it better not to check ERR here.

>
>> @@ -318,5 +377,6 @@ static struct mipi_dsi_driver innolux_panel_driver = {
>>   module_mipi_dsi_driver(innolux_panel_driver);
>>
>>   MODULE_AUTHOR("Chris Zhong <zyw@...k-chips.com>");
>> +MODULE_AUTHOR("Lin Huang <hl@...k-chips.com>");
> I don't think refactoring existing code classify as being the module author.
> Then again, I could be wrong.
>
> HTH
> Emil
>
>
>