Hi Sam, On 07-Nov-23 21:11, Sam Ravnborg wrote: > Hi Aradhya, > > On Tue, Nov 07, 2023 at 01:17:03AM +0530, Aradhya Bhatia wrote: >> Hi Sam, >> >> Thank you for the suggestion! >> >> On 06-Nov-23 18:08, Sam Ravnborg wrote: >>> Hi Aradhya, >>> >>> On Tue, Oct 31, 2023 at 12:58:46AM +0530, Aradhya Bhatia wrote: >>>> With new connector model, tc358767 will not create the connector, when >>>> DRM_BRIDGE_ATTACH_NO_CONNECTOR is set and display-controller driver will >>>> rely on format negotiation to setup the encoder format. >>>> >>>> Add the missing input-format negotiation hook in the >>>> drm_bridge_funcs to complete DRM_BRIDGE_ATTACH_NO_CONNECTOR support. >>>> >>>> Input format is selected to MEDIA_BUS_FMT_RGB888_1X24 as default, as is >>>> the case with older model. >>>> >>>> Reported-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx> >>>> Signed-off-by: Aradhya Bhatia <a-bhatia1@xxxxxx> >>>> --- >>>> >>>> Notes: >>>> >>>> * Since I do not have hardware with me, this was just build tested. I would >>>> appreciate it if someone could test and review it, especically somebody, who >>>> uses the bridge for DPI/DSI to eDP format conversion. >>>> >>>> * The Toshiba TC358767 bridge is not enabled in arm64 defconfig by default, >>>> when it should be. Hence, I sent a quick patch[0] earlier. >>>> >>>> [0]: https://lore.kernel.org/all/20231030152834.18450-1-a-bhatia1@xxxxxx/ >>>> >>>> drivers/gpu/drm/bridge/tc358767.c | 25 +++++++++++++++++++++++++ >>>> 1 file changed, 25 insertions(+) >>>> >>>> diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c >>>> index ef2e373606ba..0affcefdeb1c 100644 >>>> --- a/drivers/gpu/drm/bridge/tc358767.c >>>> +++ b/drivers/gpu/drm/bridge/tc358767.c >>>> @@ -1751,6 +1751,30 @@ tc_dpi_atomic_get_input_bus_fmts(struct drm_bridge *bridge, >>>> return input_fmts; >>>> } >>>> >>>> +static u32 * >>>> +tc_edp_atomic_get_input_bus_fmts(struct drm_bridge *bridge, >>>> + struct drm_bridge_state *bridge_state, >>>> + struct drm_crtc_state *crtc_state, >>>> + struct drm_connector_state *conn_state, >>>> + u32 output_fmt, >>>> + unsigned int *num_input_fmts) >>>> +{ >>>> + u32 *input_fmts; >>>> + >>>> + *num_input_fmts = 0; >>>> + >>>> + input_fmts = kcalloc(MAX_INPUT_SEL_FORMATS, sizeof(*input_fmts), >>>> + GFP_KERNEL); >>>> + if (!input_fmts) >>>> + return NULL; >>>> + >>>> + /* This is the DSI/DPI-end bus format */ >>>> + input_fmts[0] = MEDIA_BUS_FMT_RGB888_1X24; >>>> + *num_input_fmts = 1; >>>> + >>>> + return input_fmts; >>>> +} >>> >>> You could benefit from using the helper: >>> drm_atomic_helper_bridge_propagate_bus_fmt() >> >> You are right! >> >> Upon taking a second look, I realize that the bridge chain works with >> MEDIA_BUS_FMT_FIXED bus format, when tc358767 is being used in DPI/DSI >> to eDP mode (because the panel-bridge does not have a get_output_bus_fmt >> hook, and uses the same helper for its get_input_bus_fmt hook). My patch >> creates a deviation from that, by forcing MEDIA_BUS_FMT_RGB888_1X24 even >> when eDP is involved. >> >> Using the helper here, will certainly address this deviation. >> >> However, for the DPI/DSI to DP mode, MEDIA_BUS_FMT_RGB888_1X24 bus >> format is required, and *just* using the helper as its get_input_bus_fmt >> hook, might not be enough. >> >> Since tc358767 is the last bridge in DPI/DSI to DP mode, the >> output_fmt parameter get defaulted to MEDIA_BUS_FMT_FIXED too, as there >> is no get_output_bus_fmt hook present in the driver. If we simply us >> the helper here, the input_fmt will also get set to MEDIA_BUS_FMT_FIXED. >> This too is an unwanted deviation. >> >> It seems like the right way to address both the cases, would be by >> adding the get_output_bus_fmt hook that sets output_fmt to >> MEDIA_BUS_FMT_RGB888_1X24, as well as using the helper as the >> get_input_bus_fmt hook. >> >> If this seems good to you too, I will send a new version of Tomi's >> series[0] which incorporates this patch. > > I never managed to fully wrap my head around the bus fmt negotiation, > and as I am trying to recover from a flu this is not the time to try. > Your explanations sounds like you have grasped it so I suggest to move > ahead. > Sure, I will send a new version. Hope you recover soon! =) Regards Aradhya
