Re: [PATCH 5/5] drm/bridge: ti-tfp410: Report input bus config through bridge timings

[Jyri Sarha <jsarha@ti.com>]

On 06/12/2018 22:26, Laurent Pinchart wrote:
> The TFP410 supports configurable pixel clock sampling edge and data
> de-skew adjustments. The configuration can be set through I2C or
> dedicated chip pins.
> 
> Report the configuration through the drm_bridge timings. As the
> ti-tftp410 driver doesn't support configuring the chip through I2C, we
> simply use the default configuration in that case. When the chip is
> configured through dedicated pins, we parse the configuration from DT.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> ---
>  drivers/gpu/drm/bridge/ti-tfp410.c | 77 ++++++++++++++++++++++++++++--
>  1 file changed, 74 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/ti-tfp410.c b/drivers/gpu/drm/bridge/ti-tfp410.c
> index d25d23cfe3f5..48ec647a7526 100644
> --- a/drivers/gpu/drm/bridge/ti-tfp410.c
> +++ b/drivers/gpu/drm/bridge/ti-tfp410.c
> @@ -34,6 +34,8 @@ struct tfp410 {
>  	struct delayed_work	hpd_work;
>  	struct gpio_desc	*powerdown;
>  
> +	struct drm_bridge_timings timings;
> +
>  	struct device *dev;
>  };
>  
> @@ -180,6 +182,70 @@ static irqreturn_t tfp410_hpd_irq_thread(int irq, void *arg)
>  	return IRQ_HANDLED;
>  }
>  
> +static const struct drm_bridge_timings tfp410_default_timings = {
> +	.input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE
> +			 | DRM_BUS_FLAG_DE_HIGH,
> +	.setup_time_ps = 1200,
> +	.hold_time_ps = 1300,
> +};
> +
> +static int tfp410_parse_timings(struct tfp410 *dvi, bool i2c)
> +{
> +	struct drm_bridge_timings *timings = &dvi->timings;
> +	struct device_node *ep;
> +	u32 pclk_sample = 0;
> +	s32 deskew = 0;
> +
> +	/* Start with defaults. */
> +	*timings = tfp410_default_timings;
> +
> +	if (i2c)
> +		/*
> +		 * In I2C mode timings are configured through the I2C interface.
> +		 * As the driver doesn't support I2C configuration yet, we just
> +		 * go with the defaults (BSEL=1, DSEL=1, DKEN=0, EDGE=1).
> +		 */
> +		return 0;
> +
> +	/*
> +	 * In non-I2C mode, timings are configured through the BSEL, DSEL, DKEN
> +	 * and EDGE pins. They are specified in DT through endpoint properties
> +	 * and vendor-specific properties.
> +	 */
> +	ep = of_graph_get_endpoint_by_regs(dvi->dev->of_node, 0, 0);
> +	if (!ep)
> +		return -EINVAL;
> +
> +	/* Get the sampling edge from the endpoint. */
> +	of_property_read_u32(ep, "pclk-sample", &pclk_sample);
> +	of_node_put(ep);
> +
> +	timings->input_bus_flags = DRM_BUS_FLAG_DE_HIGH;
> +
> +	switch (pclk_sample) {
> +	case 0:
> +		timings->input_bus_flags |= DRM_BUS_FLAG_PIXDATA_SAMPLE_NEGEDGE
> +					 |  DRM_BUS_FLAG_SYNC_SAMPLE_NEGEDGE;
> +		break;
> +	case 1:
> +		timings->input_bus_flags |= DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE
> +					 |  DRM_BUS_FLAG_SYNC_SAMPLE_POSEDGE;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	/* Get the setup and hold time from vendor-specific properties. */
> +	of_property_read_u32(dvi->dev->of_node, "ti,deskew", (u32 *)&deskew);
> +	if (deskew < -4 || deskew > 3)
> +		return -EINVAL;

Is "ti,deskew" property documented somewhere? If it is, I could not find
it. Could it be added to the tfp410 binding document, or somewhere else?

Othewise:

Reviewed-by: Jyri Sarha <jsarha@ti.com>

> +
> +	timings->setup_time_ps = min(0, 1200 - 350 * deskew);
> +	timings->hold_time_ps = min(0, 1300 + 350 * deskew);
> +
> +	return 0;
> +}
> +
>  static int tfp410_get_connector_properties(struct tfp410 *dvi)
>  {
>  	struct device_node *connector_node, *ddc_phandle;
> @@ -223,7 +289,7 @@ static int tfp410_get_connector_properties(struct tfp410 *dvi)
>  	return ret;
>  }
>  
> -static int tfp410_init(struct device *dev)
> +static int tfp410_init(struct device *dev, bool i2c)
>  {
>  	struct tfp410 *dvi;
>  	int ret;
> @@ -240,8 +306,13 @@ static int tfp410_init(struct device *dev)
>  
>  	dvi->bridge.funcs = &tfp410_bridge_funcs;
>  	dvi->bridge.of_node = dev->of_node;
> +	dvi->bridge.timings = &dvi->timings;
>  	dvi->dev = dev;
>  
> +	ret = tfp410_parse_timings(dvi, i2c);
> +	if (ret)
> +		goto fail;
> +
>  	ret = tfp410_get_connector_properties(dvi);
>  	if (ret)
>  		goto fail;
> @@ -294,7 +365,7 @@ static int tfp410_fini(struct device *dev)
>  
>  static int tfp410_probe(struct platform_device *pdev)
>  {
> -	return tfp410_init(&pdev->dev);
> +	return tfp410_init(&pdev->dev, false);
>  }
>  
>  static int tfp410_remove(struct platform_device *pdev)
> @@ -331,7 +402,7 @@ static int tfp410_i2c_probe(struct i2c_client *client,
>  		return -ENXIO;
>  	}
>  
> -	return tfp410_init(&client->dev);
> +	return tfp410_init(&client->dev, true);
>  }
>  
>  static int tfp410_i2c_remove(struct i2c_client *client)
> 


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