Re: [PATCH v4 2/3] drm/tegra: output: Support DRM bridges

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Dmitry,

Thank you for the patch.

On Fri, Apr 17, 2020 at 08:52:37PM +0300, Dmitry Osipenko wrote:
> Newer Tegra device-trees will specify a video output graph which involves
> a bridge. This patch adds initial support for the DRM bridges to the
> Tegra's DRM output.
> 
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/gpu/drm/tegra/drm.h    |  2 ++
>  drivers/gpu/drm/tegra/output.c | 13 ++++++++++++-
>  2 files changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/tegra/drm.h b/drivers/gpu/drm/tegra/drm.h
> index 804869799305..cccd368b6752 100644
> --- a/drivers/gpu/drm/tegra/drm.h
> +++ b/drivers/gpu/drm/tegra/drm.h
> @@ -12,6 +12,7 @@
>  #include <linux/of_gpio.h>
>  
>  #include <drm/drm_atomic.h>
> +#include <drm/drm_bridge.h>

You could add a forward declaration of struct drm_bridge instead, that
can lower the compilation time a little bit.

>  #include <drm/drm_edid.h>
>  #include <drm/drm_encoder.h>
>  #include <drm/drm_fb_helper.h>
> @@ -116,6 +117,7 @@ struct tegra_output {
>  	struct device_node *of_node;
>  	struct device *dev;
>  
> +	struct drm_bridge *bridge;
>  	struct drm_panel *panel;
>  	struct i2c_adapter *ddc;
>  	const struct edid *edid;
> diff --git a/drivers/gpu/drm/tegra/output.c b/drivers/gpu/drm/tegra/output.c
> index a6a711d54e88..ec0cd4a1ced1 100644
> --- a/drivers/gpu/drm/tegra/output.c
> +++ b/drivers/gpu/drm/tegra/output.c
> @@ -5,6 +5,7 @@
>   */
>  
>  #include <drm/drm_atomic_helper.h>
> +#include <drm/drm_of.h>
>  #include <drm/drm_panel.h>
>  #include <drm/drm_simple_kms_helper.h>
>  
> @@ -92,13 +93,23 @@ static irqreturn_t hpd_irq(int irq, void *data)
>  
>  int tegra_output_probe(struct tegra_output *output)
>  {
> -	struct device_node *ddc, *panel;
> +	struct device_node *ddc, *panel, *port;
>  	unsigned long flags;
>  	int err, size;
>  
>  	if (!output->of_node)
>  		output->of_node = output->dev->of_node;
>  
> +	port = of_get_child_by_name(output->of_node, "port");

Do you need to check for the presence of a port node first ? Can you
just check the return value of drm_of_find_panel_or_bridge(), and fall
back to "nvidia,panel" if it returns -ENODEV ?

> +	if (port) {
> +		err = drm_of_find_panel_or_bridge(output->of_node, 0, 0, NULL,
> +						  &output->bridge);
> +		of_node_put(port);
> +
> +		if (err)
> +			return err;
> +	}
> +
>  	panel = of_parse_phandle(output->of_node, "nvidia,panel", 0);
>  	if (panel) {
>  		output->panel = of_drm_find_panel(panel);

-- 
Regards,

Laurent Pinchart
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