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. Regards Aradhya [0]: https://lore.kernel.org/all/20231031-tc358767-v1-0-392081ad9f4b@xxxxxxxxxxxxxxxx/
