When the dw-hdmi bridge is in first place of the bridge chain, this means there is now way to select an input format of the dw-hdmi HW component.
Since introduction of display-connector, negociation was broken since the dw-hdmi negociation code only worked when the dw-hdmi bridge was in last position of the bridge chain or behind another bridge also supporting input & output format negociation.
Commit 0656d1285b79 ("drm/bridge: display-connector: implement bus fmts callbacks") was introduced to make negociation work again by making display-connector act as a pass-through concerning input & output format negociation.
But in the case were the dw-hdmi was single in the bridge chain, for example on Renesas SoCs, with the disply-connector bridge the dw-hdmi is no more single, breaking output format.
Reported-by: Biju Das biju.das.jz@bp.renesas.com Bisected-by: Kieran Bingham kieran.bingham+renesas@ideasonboard.com Tested-by: Kieran Bingham kieran.bingham+renesas@ideasonboard.com Fixes: 0656d1285b79 ("drm/bridge: display-connector: implement bus fmts callbacks"). Signed-off-by: Neil Armstrong narmstrong@baylibre.com --- drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c index 54d8fdad395f..9f2e1cac0ae2 100644 --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c @@ -2551,8 +2551,9 @@ static u32 *dw_hdmi_bridge_atomic_get_output_bus_fmts(struct drm_bridge *bridge, if (!output_fmts) return NULL;
- /* If dw-hdmi is the only bridge, avoid negociating with ourselves */ - if (list_is_singular(&bridge->encoder->bridge_chain)) { + /* If dw-hdmi is the first or only bridge, avoid negociating with ourselves */ + if (list_is_singular(&bridge->encoder->bridge_chain) || + list_is_first(&bridge->chain_node, &bridge->encoder->bridge_chain)) { *num_output_fmts = 1; output_fmts[0] = MEDIA_BUS_FMT_FIXED;
@@ -2673,6 +2674,10 @@ static u32 *dw_hdmi_bridge_atomic_get_input_bus_fmts(struct drm_bridge *bridge, if (!input_fmts) return NULL;
+ /* If dw-hdmi is the first bridge fall-back to safe output format */ + if (list_is_first(&bridge->chain_node, &bridge->encoder->bridge_chain)) + output_fmt = MEDIA_BUS_FMT_FIXED; + switch (output_fmt) { /* If MEDIA_BUS_FMT_FIXED is tested, return default bus format */ case MEDIA_BUS_FMT_FIXED: