This is a note to let you know that I've just added the patch titled drm/bridge: dw-hdmi: use safe format when first in bridge chain to the 5.17-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: drm-bridge-dw-hdmi-use-safe-format-when-first-in-bri.patch and it can be found in the queue-5.17 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 565d5b7e8a0190d4a5b98ea03d3f9835893ea2ec Author: Neil Armstrong <narmstrong@xxxxxxxxxxxx> Date: Fri Feb 4 15:33:37 2022 +0100 drm/bridge: dw-hdmi: use safe format when first in bridge chain [ Upstream commit 1528038385c0a706aac9ac165eeb24044fef6825 ] When the dw-hdmi bridge is in first place of the bridge chain, this means there is no way to select an input format of the dw-hdmi HW component. Since introduction of display-connector, negotiation was broken since the dw-hdmi negotiation 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 negotiation. Commit 7cd70656d128 ("drm/bridge: display-connector: implement bus fmts callbacks") was introduced to make negotiation work again by making display-connector act as a pass-through concerning input & output format negotiation. But in the case where the dw-hdmi is single in the bridge chain, for example on Renesas SoCs, with the display-connector bridge the dw-hdmi is no more single, breaking output format. Reported-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx> Bisected-by: Kieran Bingham <kieran.bingham+renesas@xxxxxxxxxxxxxxxx> Tested-by: Kieran Bingham <kieran.bingham+renesas@xxxxxxxxxxxxxxxx> Fixes: 6c3c719936da ("drm/bridge: synopsys: dw-hdmi: add bus format negociation") Signed-off-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx> [narmstrong: add proper fixes commit] Reviewed-by: Robert Foss <robert.foss@xxxxxxxxxx> Link: https://patchwork.freedesktop.org/patch/msgid/20220204143337.89221-1-narmstrong@xxxxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c index 54d8fdad395f..97cdc61b57f6 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;