[1/2] drm: bridge: samsung-dsim: Initialize bridge on attach

[Alexander Stein]

Hi,

Am Montag, 13. Mai 2024, 04:16:27 CEST schrieb Marek Vasut:
> Initialize the bridge on attach already, to force lanes into LP11
> state, since attach does trigger attach of downstream bridges which
> may trigger (e)DP AUX channel mode read.
> 
> This fixes a corner case where DSIM with TC9595 attached to it fails
> to operate the DP AUX channel, because the TC9595 enters some debug
> mode when it is released from reset without lanes in LP11 mode. By
> ensuring the DSIM lanes are in LP11, the TC9595 (tc358767.c driver)
> can be reset in its attach callback called from DSIM attach callback,
> and recovered out of the debug mode just before TC9595 performs first
> AUX channel access later in its attach callback.
> 
> Signed-off-by: Marek Vasut <marex at denx.de>

This does the trick on my hardware as well.
Reviewed-by: Alexander Stein <alexander.stein at ew.tq-group.com>

> ---
> Cc: Adam Ford <aford173 at gmail.com>
> Cc: Alexander Stein <alexander.stein at ew.tq-group.com>
> Cc: Andrzej Hajda <andrzej.hajda at intel.com>
> Cc: Daniel Vetter <daniel at ffwll.ch>
> Cc: David Airlie <airlied at gmail.com>
> Cc: Frieder Schrempf <frieder.schrempf at kontron.de>
> Cc: Inki Dae <inki.dae at samsung.com>
> Cc: Jagan Teki <jagan at amarulasolutions.com>
> Cc: Jernej Skrabec <jernej.skrabec at gmail.com>
> Cc: Jonas Karlman <jonas at kwiboo.se>
> Cc: Laurent Pinchart <Laurent.pinchart at ideasonboard.com>
> Cc: Lucas Stach <l.stach at pengutronix.de>
> Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> Cc: Marek Szyprowski <m.szyprowski at samsung.com>
> Cc: Maxime Ripard <mripard at kernel.org>
> Cc: Michael Walle <mwalle at kernel.org>
> Cc: Neil Armstrong <neil.armstrong at linaro.org>
> Cc: Robert Foss <rfoss at kernel.org>
> Cc: Thomas Zimmermann <tzimmermann at suse.de>
> Cc: dri-devel at lists.freedesktop.org
> Cc: kernel at dh-electronics.com
> ---
>  drivers/gpu/drm/bridge/samsung-dsim.c | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c
> index 95fedc68b0ae5..56093fc3d62cc 100644
> --- a/drivers/gpu/drm/bridge/samsung-dsim.c
> +++ b/drivers/gpu/drm/bridge/samsung-dsim.c
> @@ -1622,9 +1622,21 @@ static int samsung_dsim_attach(struct drm_bridge *bridge,
>  			       enum drm_bridge_attach_flags flags)
>  {
>  	struct samsung_dsim *dsi = bridge_to_dsi(bridge);
> +	int ret;
> +
> +	ret = pm_runtime_resume_and_get(dsi->dev);
> +	if (ret < 0)
> +		return ret;
>  
> -	return drm_bridge_attach(bridge->encoder, dsi->out_bridge, bridge,
> -				 flags);
> +	ret = samsung_dsim_init(dsi);
> +	if (ret < 0)
> +		goto err;
> +
> +	ret = drm_bridge_attach(bridge->encoder, dsi->out_bridge, bridge,
> +				flags);
> +err:
> +	pm_runtime_put_sync(dsi->dev);
> +	return ret;
>  }
>  
>  static const struct drm_bridge_funcs samsung_dsim_bridge_funcs = {
> 
> 


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