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

From: Chen-Yu Tsai
Date: Tue Nov 01 2016 - 21:33:33 EST


On Mon, Oct 31, 2016 at 2:28 PM, Rob Herring <robh@xxxxxxxxxx> 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@xxxxxxxx>
>> ---
>> .../bindings/display/bridge/dumb-vga-dac.txt | 2 ++
>
> For the binding,
>
> Acked-by: Rob Herring <robh@xxxxxxxxxx>
>
> 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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