Hi,
On 17/01/2022 17:53, Marcel Ziswiler wrote:
> Hi Neil
>
> Sorry, just some trivial spelling fixes.
>
> On Mon, 2022-01-17 at 15:17 +0100, Neil Armstrong wrote:
>> When the dw-hdmi bridge is in first place of the bridge chain, this
>> means there is now way
>
> no way
>
>> to select an input format of the dw-hdmi HW
>> component.
>>
>> Since introduction of display-connector, negociation
>
> :%s/negociation/negotiation/g
>
>> 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
>
> where
>
>> the dw-hdmi was single in the bridge chain, for
>> example on Renesas SoCs, with the disply-connector
>
> 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: 0656d1285b79 ("drm/bridge: display-connector: implement bus fmts callbacks").
>> Signed-off-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
>> ---
>> 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:
>
> Cheers
>
> Marcel
>
Thanks for the spelling fixes,
Neil
