From: Neil Armstrong narmstrong@baylibre.com
stable inclusion from stable-v5.10.110 commit f03ef518c1c1987b100b3195596542c9d44b2c99 bugzilla: https://gitee.com/openeuler/kernel/issues/I574AL
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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[ 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@bp.renesas.com Bisected-by: Kieran Bingham kieran.bingham+renesas@ideasonboard.com Tested-by: Kieran Bingham kieran.bingham+renesas@ideasonboard.com Fixes: 6c3c719936da ("drm/bridge: synopsys: dw-hdmi: add bus format negociation") Signed-off-by: Neil Armstrong narmstrong@baylibre.com [narmstrong: add proper fixes commit] Reviewed-by: Robert Foss robert.foss@linaro.org Link: https://patchwork.freedesktop.org/patch/msgid/20220204143337.89221-1-narmstr... Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Yu Liao liaoyu15@huawei.com Reviewed-by: Wei Li liwei391@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c index 29c0eb4bd754..b10228b9e3a9 100644 --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c @@ -2566,8 +2566,9 @@ 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;