linux-kernel - Re: [PATCH 5/8] drm/vc4: Delay DSI host registration until the panel has probed.

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Message-id: <957e63b0-0c95-a94b-57b3-aae3a18766b7@samsung.com>
Date:   Thu, 29 Jun 2017 11:42:24 +0200
From:   Andrzej Hajda <a.hajda@...sung.com>
To:     Eric Anholt <eric@...olt.net>, dri-devel@...ts.freedesktop.org,
        Archit Taneja <architt@...eaurora.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Thierry Reding <thierry.reding@...il.com>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/8] drm/vc4: Delay DSI host registration until the panel
 has probed.

On 27.06.2017 21:58, Eric Anholt wrote:
> The vc4 driver was unusual in that it was delaying the panel lookup
> until the attach step, while most DSI hosts will -EPROBE_DEFER until
> they get a panel.
>
> Signed-off-by: Eric Anholt <eric@...olt.net>
> ---
>  drivers/gpu/drm/vc4/vc4_dsi.c | 40 ++++++++++++++++------------------------
>  1 file changed, 16 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/gpu/drm/vc4/vc4_dsi.c b/drivers/gpu/drm/vc4/vc4_dsi.c
> index fca4d7fd677e..31627522dd8c 100644
> --- a/drivers/gpu/drm/vc4/vc4_dsi.c
> +++ b/drivers/gpu/drm/vc4/vc4_dsi.c
> @@ -33,6 +33,7 @@
>  #include <drm/drm_crtc_helper.h>
>  #include <drm/drm_edid.h>
>  #include <drm/drm_mipi_dsi.h>
> +#include <drm/drm_of.h>
>  #include <drm/drm_panel.h>
>  #include <linux/clk.h>
>  #include <linux/clk-provider.h>
> @@ -504,7 +505,6 @@ struct vc4_dsi {
>  	struct mipi_dsi_host dsi_host;
>  	struct drm_encoder *encoder;
>  	struct drm_bridge *bridge;
> -	bool is_panel_bridge;
>  
>  	void __iomem *regs;
>  
> @@ -1290,7 +1290,6 @@ static int vc4_dsi_host_attach(struct mipi_dsi_host *host,
>  			       struct mipi_dsi_device *device)
>  {
>  	struct vc4_dsi *dsi = host_to_dsi(host);
> -	int ret = 0;
>  
>  	dsi->lanes = device->lanes;
>  	dsi->channel = device->channel;
> @@ -1325,34 +1324,12 @@ static int vc4_dsi_host_attach(struct mipi_dsi_host *host,
>  		return 0;
>  	}
>  
> -	dsi->bridge = of_drm_find_bridge(device->dev.of_node);
> -	if (!dsi->bridge) {
> -		struct drm_panel *panel =
> -			of_drm_find_panel(device->dev.of_node);
> -
> -		dsi->bridge = drm_panel_bridge_add(panel,
> -						   DRM_MODE_CONNECTOR_DSI);
> -		if (IS_ERR(dsi->bridge)) {
> -			ret = PTR_ERR(dsi->bridge);
> -			dsi->bridge = NULL;
> -			return ret;
> -		}
> -		dsi->is_panel_bridge = true;
> -	}
> -
>  	return drm_bridge_attach(dsi->encoder, dsi->bridge, NULL);
>  }
>  
>  static int vc4_dsi_host_detach(struct mipi_dsi_host *host,
>  			       struct mipi_dsi_device *device)
>  {
> -	struct vc4_dsi *dsi = host_to_dsi(host);
> -
> -	if (dsi->is_panel_bridge) {
> -		drm_panel_bridge_remove(dsi->bridge);
> -		dsi->bridge = NULL;
> -	}
> -
>  	return 0;
>  }
>  
> @@ -1496,6 +1473,7 @@ static int vc4_dsi_bind(struct device *dev, struct device *master, void *data)
>  	struct vc4_dev *vc4 = to_vc4_dev(drm);
>  	struct vc4_dsi *dsi;
>  	struct vc4_dsi_encoder *vc4_dsi_encoder;
> +	struct drm_panel *panel;
>  	const struct of_device_id *match;
>  	dma_cap_mask_t dma_mask;
>  	int ret;
> @@ -1599,6 +1577,20 @@ static int vc4_dsi_bind(struct device *dev, struct device *master, void *data)
>  		return ret;
>  	}
>  
> +	ret = drm_of_find_panel_or_bridge(dev->of_node, 0, 0,
> +					  &panel, &dsi->bridge);
> +	if (ret) {
> +		dev_info(dev, "find panel: %d\n", ret);

Message should probably mention also bridge.
Beside this:
Reviewed-by: Andrzej Hajda <a.hajda@...sung.com>

 --
Regards
Andrzej

> +		return ret;
> +	}
> +
> +	if (panel) {
> +		dsi->bridge = devm_drm_panel_bridge_add(dev, panel,
> +							DRM_MODE_CONNECTOR_DSI);
> +		if (IS_ERR(dsi->bridge))
> +			return PTR_ERR(dsi->bridge);
> +	}
> +
>  	/* The esc clock rate is supposed to always be 100Mhz. */
>  	ret = clk_set_rate(dsi->escape_clock, 100 * 1000000);
>  	if (ret) {