Hi Marek,
All my apologies for the awfully delayed review, and thank you for
pinging me.
On Thu, Dec 24, 2020 at 07:18:32AM +0100, Marek Vasut wrote:
> The OnSemi FIN3385 Parallel-to-LVDS encoder has a dedicated input line to
> select input pixel data sampling edge. Add DT property "pixelclk-active",
> same as the one used by display timings, and configure bus flags based on
> this DT property.
>
> Signed-off-by: Marek Vasut <marex@xxxxxxx>
> Cc: Alexandre Torgue <alexandre.torgue@xxxxxx>
> Cc: Andrzej Hajda <a.hajda@xxxxxxxxxxx>
> Cc: Antonio Borneo <antonio.borneo@xxxxxx>
> Cc: Benjamin Gaignard <benjamin.gaignard@xxxxxx>
> Cc: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> Cc: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> Cc: Maxime Coquelin <mcoquelin.stm32@xxxxxxxxx>
> Cc: Philippe Cornu <philippe.cornu@xxxxxx>
> Cc: Sam Ravnborg <sam@xxxxxxxxxxxx>
> Cc: Vincent Abriou <vincent.abriou@xxxxxx>
> Cc: Yannick Fertre <yannick.fertre@xxxxxx>
> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> Cc: linux-stm32@xxxxxxxxxxxxxxxxxxxxxxxxxxxx
> To: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> ---
> V2: - Limit the pixelclk-active to encoders only
> - Update DT binding document
> ---
> .../bindings/display/bridge/lvds-codec.yaml | 7 +++
> drivers/gpu/drm/bridge/lvds-codec.c | 52 +++++++++++++------
> 2 files changed, 44 insertions(+), 15 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/display/bridge/lvds-codec.yaml b/Documentation/devicetree/bindings/display/bridge/lvds-codec.yaml
> index e5e3c72630cf..399a6528780a 100644
> --- a/Documentation/devicetree/bindings/display/bridge/lvds-codec.yaml
> +++ b/Documentation/devicetree/bindings/display/bridge/lvds-codec.yaml
> @@ -74,6 +74,13 @@ properties:
>
> additionalProperties: false
>
> + pixelclk-active:
> + description: |
> + Data sampling on rising or falling edge.
> + Use 0 to sample pixel data on rising edge and
> + Use 1 to sample pixel data on falling edge and
> + enum: [0, 1]
The idea is good, but instead of adding a custom property, how about
reusing the pclk-sample property defined in
../../media/video-interfaces.yaml ?
The property is only valid for encoders, so I would at least mention
that in the description, or, better, handle this based on the compatible
string to allow validation.
> +
> powerdown-gpios:
> description:
> The GPIO used to control the power down line of this device.
> diff --git a/drivers/gpu/drm/bridge/lvds-codec.c b/drivers/gpu/drm/bridge/lvds-codec.c
> index dcf579a4cf83..cab81ccd895d 100644
> --- a/drivers/gpu/drm/bridge/lvds-codec.c
> +++ b/drivers/gpu/drm/bridge/lvds-codec.c
> @@ -15,13 +15,18 @@
> #include <drm/drm_bridge.h>
> #include <drm/drm_panel.h>
>
> +struct lvds_codec_data {
> + u32 connector_type;
> + bool is_encoder;
> +};
> +
> struct lvds_codec {
> struct device *dev;
> struct drm_bridge bridge;
> struct drm_bridge *panel_bridge;
> + struct drm_bridge_timings timings;
> struct regulator *vcc;
> struct gpio_desc *powerdown_gpio;
> - u32 connector_type;
> };
>
> static inline struct lvds_codec *to_lvds_codec(struct drm_bridge *bridge)
> @@ -76,17 +81,20 @@ static const struct drm_bridge_funcs funcs = {
>
> static int lvds_codec_probe(struct platform_device *pdev)
> {
> + const struct lvds_codec_data *data;
> struct device *dev = &pdev->dev;
> struct device_node *panel_node;
> struct drm_panel *panel;
> struct lvds_codec *lvds_codec;
> + u32 val;
>
> lvds_codec = devm_kzalloc(dev, sizeof(*lvds_codec), GFP_KERNEL);
> if (!lvds_codec)
> return -ENOMEM;
>
> + data = of_device_get_match_data(dev);
> +
> lvds_codec->dev = &pdev->dev;
> - lvds_codec->connector_type = (uintptr_t)of_device_get_match_data(dev);
>
> lvds_codec->vcc = devm_regulator_get(lvds_codec->dev, "power");
> if (IS_ERR(lvds_codec->vcc))
> @@ -115,10 +123,22 @@ static int lvds_codec_probe(struct platform_device *pdev)
>
> lvds_codec->panel_bridge =
> devm_drm_panel_bridge_add_typed(dev, panel,
> - lvds_codec->connector_type);
> + data->connector_type);
> if (IS_ERR(lvds_codec->panel_bridge))
> return PTR_ERR(lvds_codec->panel_bridge);
>
> + /*
> + * Encoder might sample data on different clock edge than the display,
> + * for example OnSemi FIN3385 has a dedicated strapping pin to select
> + * the sampling edge.
> + */
> + if (data->is_encoder &&
> + !of_property_read_u32(dev->of_node, "pixelclk-active", &val)) {
> + lvds_codec->timings.input_bus_flags = val ?
> + DRM_BUS_FLAG_PIXDATA_SAMPLE_NEGEDGE :
> + DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE;
> + }
> +
> /*
> * The panel_bridge bridge is attached to the panel's of_node,
> * but we need a bridge attached to our of_node for our user
> @@ -126,6 +146,7 @@ static int lvds_codec_probe(struct platform_device *pdev)
> */
> lvds_codec->bridge.of_node = dev->of_node;
> lvds_codec->bridge.funcs = &funcs;
> + lvds_codec->bridge.timings = &lvds_codec->timings;
> drm_bridge_add(&lvds_codec->bridge);
>
> platform_set_drvdata(pdev, lvds_codec);
> @@ -142,19 +163,20 @@ static int lvds_codec_remove(struct platform_device *pdev)
> return 0;
> }
>
> +static const struct lvds_codec_data decoder_data = {
> + .connector_type = DRM_MODE_CONNECTOR_DPI,
> + .is_encoder = false,
The two fields are a bit redundant, as the decoder is always
LVDS-to-DPI, and the encoder DPI-to-LVDS. I don't mind too much, but
maybe we could drop the connector_type field, and derive the connector
type from is_encoder ?
One may then say that we could drop the lvds_codec_data structure as it
contains a single field, but I foresee a need to have device-specific
timings at some point, so I think it's a good addition.
The patch otherwise looks good.
> +};
> +
> +static const struct lvds_codec_data encoder_data = {
> + .connector_type = DRM_MODE_CONNECTOR_LVDS,
> + .is_encoder = true,
> +};
> +
> static const struct of_device_id lvds_codec_match[] = {
> - {
> - .compatible = "lvds-decoder",
> - .data = (void *)DRM_MODE_CONNECTOR_DPI,
> - },
> - {
> - .compatible = "lvds-encoder",
> - .data = (void *)DRM_MODE_CONNECTOR_LVDS,
> - },
> - {
> - .compatible = "thine,thc63lvdm83d",
> - .data = (void *)DRM_MODE_CONNECTOR_LVDS,
> - },
> + { .compatible = "lvds-decoder", .data = &decoder_data, },
> + { .compatible = "lvds-encoder", .data = &encoder_data, },
> + { .compatible = "thine,thc63lvdm83d", .data = &encoder_data, },
> {},
> };
> MODULE_DEVICE_TABLE(of, lvds_codec_match);
--
Regards,
Laurent Pinchart
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