[PATCH] drm: exynos: dsi: Use child panel or bridge find helpers

[Maxime Ripard]

On Thu, Apr 28, 2022 at 03:18:08PM +0530, Jagan Teki wrote:
> commit <711c7adc4687> ("drm: exynos: dsi: Use drm panel_bridge API")
> added devm_drm_of_get_bridge for looking up if child node has panel
> or bridge.
> 
> However commit <b089c0a9b14c> ("Revert "drm: of: Lookup if child node
> has panel or bridge") has reverted panel or bridge child node lookup
> from devm_drm_of_get_bridge which eventually failed to find the DSI
> devices in exynos drm dsi driver.
> 
> So, use the conventional child panel bridge lookup helpers like it
> does before.
> 
> Signed-off-by: Jagan Teki <jagan at amarulasolutions.com>
> ---
>  drivers/gpu/drm/exynos/exynos_drm_dsi.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> index f067c86b0b12..ec673223d6b7 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> @@ -25,6 +25,7 @@
>  #include <drm/drm_atomic_helper.h>
>  #include <drm/drm_bridge.h>
>  #include <drm/drm_mipi_dsi.h>
> +#include <drm/drm_panel.h>
>  #include <drm/drm_print.h>
>  #include <drm/drm_probe_helper.h>
>  #include <drm/drm_simple_kms_helper.h>
> @@ -1451,9 +1452,18 @@ static int exynos_dsi_host_attach(struct mipi_dsi_host *host,
>  	struct device *dev = dsi->dev;
>  	struct drm_encoder *encoder = &dsi->encoder;
>  	struct drm_device *drm = encoder->dev;
> +	struct drm_panel *panel;
>  	int ret;
>  
> -	dsi->out_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 1, 0);
> +	panel = of_drm_find_panel(device->dev.of_node);
> +	if (!IS_ERR(panel)) {
> +		dsi->out_bridge = devm_drm_panel_bridge_add(dev, panel);
> +	} else {
> +		dsi->out_bridge = of_drm_find_bridge(device->dev.of_node);
> +		if (!dsi->out_bridge)
> +			dsi->out_bridge = ERR_PTR(-EINVAL);
> +	}
> +

We should just revert 711c7adc4687 entirely (and make it very explicit
in the commit log). The out_bridge lifetime is completely screwed-up in
that patch now. If there's a panel it will be managed, but it's not if
there's a bridge.

Maxime
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