Hi Marek,
thanks for the patch.
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>
> ---
> 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 = {
>
It seems the right thing to do. But if 'samsung,burst-clock-frequency' is
not specified for DSIM I get a DSI PLL configuration failure. There is no
mode yet, thus samsung_dsim_enable_clock() tries to configure the PLL for
0Hz. There is another reconfiguration while pre_enabling the chain targeting
the correct clock (891000000Hz for 1920x1080), so this seems fine.
But I'm not sure if the 1st config error has any negative side effects.
Best regards,
Alexander
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