linux-kernel - Re: [linux-sunxi] Re: [PATCH v3 1/2] drm/bridge: dumb-vga-dac: Support a VDD regulator supply

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Message-ID: <CAGb2v67LR4KEb0tfGkT8+TqTauNyCMq1n6mRdXsa6TUJV0xncA@mail.gmail.com>
Date:   Tue, 15 Nov 2016 10:59:49 +0800
From:   Chen-Yu Tsai <wens@...e.org>
To:     David Airlie <airlied@...ux.ie>
Cc:     Chen-Yu Tsai <wens@...e.org>, Rob Herring <robh@...nel.org>,
        Maxime Ripard <maxime.ripard@...e-electrons.com>,
        Mark Rutland <mark.rutland@....com>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        linux-sunxi <linux-sunxi@...glegroups.com>
Subject: Re: [linux-sunxi] Re: [PATCH v3 1/2] drm/bridge: dumb-vga-dac:
 Support a VDD regulator supply

Hi,

On Wed, Nov 2, 2016 at 9:33 AM, Chen-Yu Tsai <wens@...e.org> wrote:
> On Mon, Oct 31, 2016 at 2:28 PM, Rob Herring <robh@...nel.org> wrote:
>> On Sat, Oct 29, 2016 at 07:06:10PM +0800, Chen-Yu Tsai wrote:
>>> Some dumb VGA DACs are active components which require external power.
>>> Add support for specifying a regulator as its power supply.
>>>
>>> Signed-off-by: Chen-Yu Tsai <wens@...e.org>
>>> ---
>>>  .../bindings/display/bridge/dumb-vga-dac.txt       |  2 ++
>>
>> For the binding,
>>
>> Acked-by: Rob Herring <robh@...nel.org>

Any comments on this patch from the DRM people?

ChenYu

>>
>> One code comment below...
>>
>>>  drivers/gpu/drm/bridge/dumb-vga-dac.c              | 35 ++++++++++++++++++++++
>>>  2 files changed, 37 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/display/bridge/dumb-vga-dac.txt b/Documentation/devicetree/bindings/display/bridge/dumb-vga-dac.txt
>>> index 003bc246a270..164cbb15f04c 100644
>>> --- a/Documentation/devicetree/bindings/display/bridge/dumb-vga-dac.txt
>>> +++ b/Documentation/devicetree/bindings/display/bridge/dumb-vga-dac.txt
>>> @@ -16,6 +16,8 @@ graph bindings specified in Documentation/devicetree/bindings/graph.txt.
>>>  - Video port 0 for RGB input
>>>  - Video port 1 for VGA output
>>>
>>> +Optional properties:
>>> +- vdd-supply: Power supply for DAC
>>>
>>>  Example
>>>  -------
>>> diff --git a/drivers/gpu/drm/bridge/dumb-vga-dac.c b/drivers/gpu/drm/bridge/dumb-vga-dac.c
>>> index afec232185a7..59781e031220 100644
>>> --- a/drivers/gpu/drm/bridge/dumb-vga-dac.c
>>> +++ b/drivers/gpu/drm/bridge/dumb-vga-dac.c
>>> @@ -12,6 +12,7 @@
>>>
>>>  #include <linux/module.h>
>>>  #include <linux/of_graph.h>
>>> +#include <linux/regulator/consumer.h>
>>>
>>>  #include <drm/drmP.h>
>>>  #include <drm/drm_atomic_helper.h>
>>> @@ -23,6 +24,7 @@ struct dumb_vga {
>>>       struct drm_connector    connector;
>>>
>>>       struct i2c_adapter      *ddc;
>>> +     struct regulator        *vdd;
>>>  };
>>>
>>>  static inline struct dumb_vga *
>>> @@ -124,8 +126,33 @@ static int dumb_vga_attach(struct drm_bridge *bridge)
>>>       return 0;
>>>  }
>>>
>>> +static void dumb_vga_enable(struct drm_bridge *bridge)
>>> +{
>>> +     struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
>>> +     int ret;
>>> +
>>> +     if (!IS_ERR(vga->vdd)) {
>>
>> if (IS_ERR())
>>         return;
>>
>> ...will save some intentation.
>
> I thought about that, though if someone were to add more stuff to
> this, such as an enable GPIO, they might have to rework it. A standalone
> block of code would be easier to work with. I'm OK either way though.
>
> ChenYu
>
>>
>>> +             ret = regulator_enable(vga->vdd);
>>> +
>>> +             if (ret) {
>>> +                     DRM_ERROR("Failed to enable vdd regulator: %d\n", ret);
>>> +                     return;
>>> +             }
>>> +     }
>>> +}
>>> +
>>> +static void dumb_vga_disable(struct drm_bridge *bridge)
>>> +{
>>> +     struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
>>> +
>>> +     if (!IS_ERR(vga->vdd))
>>> +             regulator_disable(vga->vdd);
>>> +}
>>> +
>>>  static const struct drm_bridge_funcs dumb_vga_bridge_funcs = {
>>>       .attach         = dumb_vga_attach,
>>> +     .enable         = dumb_vga_enable,
>>> +     .disable        = dumb_vga_disable,
>>>  };
>>>
>>>  static struct i2c_adapter *dumb_vga_retrieve_ddc(struct device *dev)
>>> @@ -169,6 +196,14 @@ static int dumb_vga_probe(struct platform_device *pdev)
>>>               return -ENOMEM;
>>>       platform_set_drvdata(pdev, vga);
>>>
>>> +     vga->vdd = devm_regulator_get_optional(&pdev->dev, "vdd");
>>> +     if (IS_ERR(vga->vdd)) {
>>> +             ret = PTR_ERR(vga->vdd);
>>> +             if (ret == -EPROBE_DEFER)
>>> +                     return -EPROBE_DEFER;
>>> +             dev_dbg(&pdev->dev, "No vdd regulator found: %d\n", ret);
>>> +     }
>>> +
>>>       vga->ddc = dumb_vga_retrieve_ddc(&pdev->dev);
>>>       if (IS_ERR(vga->ddc)) {
>>>               if (PTR_ERR(vga->ddc) == -ENODEV) {
>>> --
>>> 2.9.3
>>>
>>
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