linux-kernel - Re: [PATCH] drm/bridge: adv7511: Attach to DSI host at probe time

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Date:   Tue, 25 Jun 2019 09:39:20 +0000
From:   Matt Redfearn <matt.redfearn@...nci.com>
To:     Matthew Redfearn <matthew.redfearn@...nci.com>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>
CC:     "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        Luc Van Oostenryck <luc.vanoostenryck@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Jia-Ju Bai <baijiaju1990@...il.com>,
        Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
        David Airlie <airlied@...ux.ie>,
        Sean Paul <seanpaul@...omium.org>,
        Daniel Vetter <daniel@...ll.ch>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...l.net>
Subject: Re: [PATCH] drm/bridge: adv7511: Attach to DSI host at probe time

Hi,

Any feedback on this patch?

Thanks,
Matt

On 24/04/2019 14:22, Matthew Redfearn wrote:
> In contrast to all of the DSI panel drivers in drivers/gpu/drm/panel
> which attach to the DSI host via mipi_dsi_attach() at probe time, the
> ADV7533 bridge device does not. Instead it defers this to the point that
> the upstream device connects to its bridge via drm_bridge_attach().
> The generic Synopsys MIPI DSI host driver does not register it's own
> drm_bridge until the MIPI DSI has attached. But it does not call
> drm_bridge_attach() on the downstream device until the upstream device
> has attached. This leads to a chicken and the egg failure and the DRM
> pipeline does not complete.
> Since all other mipi_dsi_device drivers call mipi_dsi_attach() in
> probe(), make the adv7533 mipi_dsi_device do the same. This ensures that
> the Synopsys MIPI DSI host registers it's bridge such that it is
> available for the upstream device to connect to.
> 
> Signed-off-by: Matt Redfearn <matt.redfearn@...nci.com>
> 
> ---
> 
>   drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 9 +++++----
>   1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> index e7ddd3e3db9..ea36ac3a3de 100644
> --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> @@ -874,9 +874,6 @@ static int adv7511_bridge_attach(struct drm_bridge *bridge)
>   				 &adv7511_connector_helper_funcs);
>   	drm_connector_attach_encoder(&adv->connector, bridge->encoder);
>   
> -	if (adv->type == ADV7533)
> -		ret = adv7533_attach_dsi(adv);
> -
>   	if (adv->i2c_main->irq)
>   		regmap_write(adv->regmap, ADV7511_REG_INT_ENABLE(0),
>   			     ADV7511_INT0_HPD);
> @@ -1222,7 +1219,11 @@ static int adv7511_probe(struct i2c_client *i2c, const struct i2c_device_id *id)
>   	drm_bridge_add(&adv7511->bridge);
>   
>   	adv7511_audio_init(dev, adv7511);
> -	return 0;
> +
> +	if (adv7511->type == ADV7533)
> +		return adv7533_attach_dsi(adv7511);
> +	else
> +		return 0;
>   
>   err_unregister_cec:
>   	i2c_unregister_device(adv7511->i2c_cec);
>