Hi,

On 11/15/2016 08:29 AM, Chen-Yu Tsai wrote:

Hi,

On Wed, Nov 2, 2016 at 9:33 AM, Chen-Yu Tsai [off-list ref] wrote:

quoted

On Mon, Oct 31, 2016 at 2:28 PM, Rob Herring [off-list ref] wrote:

quoted

On Sat, Oct 29, 2016 at 07:06:10PM +0800, Chen-Yu Tsai wrote:

quoted

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 <redacted>
---
 .../bindings/display/bridge/dumb-vga-dac.txt       |  2 ++

For the binding,

Acked-by: Rob Herring <redacted>

Any comments on this patch from the DRM people?

A comment below.

ChenYu

quoted

quoted

One code comment below...

quoted

 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

quoted

quoted

+             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);

A cleaner way would be to set vga->vdd to NULL here, and do:

	int ret = 0;

	if (vga->vdd)
		ret = regulator_enable(vga->vdd);

	if (ret) {
		...
		return;
	}

	/* if a gpio is added later */
	if (vga->gpio)
		ret = gpiod_set_value_cansleep(vga->gpio, 1);

	if (ret) {
		...
		return;
	}
	...

We don't really care what error code is contained in vga->vdd once we have
identified whether we got a regulator or not.

The same thing can be done for ddc too, but that can done left for later.

If you're okay with the suggestion, can you re-spin a patch?

Thanks,
Archit

quoted

quoted

quoted

+     }
+
      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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