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@xxxxxxx>
This does the trick on my hardware as well.
Reviewed-by: Alexander Stein <alexander.stein@xxxxxxxxxxxxxxx>
> ---
> Cc: Adam Ford <aford173@xxxxxxxxx>
> Cc: Alexander Stein <alexander.stein@xxxxxxxxxxxxxxx>
> Cc: Andrzej Hajda <andrzej.hajda@xxxxxxxxx>
> Cc: Daniel Vetter <daniel@xxxxxxxx>
> Cc: David Airlie <airlied@xxxxxxxxx>
> Cc: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>
> Cc: Inki Dae <inki.dae@xxxxxxxxxxx>
> Cc: Jagan Teki <jagan@xxxxxxxxxxxxxxxxxxxx>
> Cc: Jernej Skrabec <jernej.skrabec@xxxxxxxxx>
> Cc: Jonas Karlman <jonas@xxxxxxxxx>
> Cc: Laurent Pinchart <Laurent.pinchart@xxxxxxxxxxxxxxxx>
> Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> Cc: Maxime Ripard <mripard@xxxxxxxxxx>
> Cc: Michael Walle <mwalle@xxxxxxxxxx>
> Cc: Neil Armstrong <neil.armstrong@xxxxxxxxxx>
> Cc: Robert Foss <rfoss@xxxxxxxxxx>
> Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> Cc: kernel@xxxxxxxxxxxxxxxxxx
> ---
> 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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