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For the bridge to work properly, this series also > > > > > changes the following in the dt-bindings and simple-bridge driver: > > > > > > > > > > - dt-bindings: Add a new compatible for the bridge in the simple-bridge > > > > > binding. This is necessary because the existing dumb-vga-dac compatible > > > > > doesn't describe a data-enable signal polarity. > > > > > > > > > > - simple-bridge: Add the VGA bridge match-table entry and timings > > > > > struct, setting the DRM_BUS_FLAG_DE_LOW flag for the bridge. > > > > > > > > Is there schematics available anywhere ? That would help reviewing the > > > > series ? > > > > > > This circuit is on the SoM, and the SoM schematics are > > > confidential and not generally available. > > > > > > I tried to extract as ascii art the relevant circuit, hope it helps > > > > Thank you, it makes things clearer. > > > > The circuit seems fairly generic. Wouldn't it be better to add an > > optional property ot the dumb-vga-dac instead of a new compatible string > > specific to Apalis ? > > See the diff below, this was the initial idea we had when working on > this. On one hand, at least to me it seems like something that other > bridges could use, and a new property seems reasonable. On the other, > since we don't know exactly how much configuration is expected from a > bridge in the simple-bridge driver, we weren't sure if this would be > accepted, and went with the simpler solution of creating a new binding > for our bridge, which also seemed less intrusive. Look like add data-enable-active make sense at this case. You can try it. Frank > > What are your thoughts about a change like this? > > diff --git a/drivers/gpu/drm/bridge/simple-bridge.c b/drivers/gpu/drm/bridge/simple-bridge.c > index 3fba7002322e..41b00a44983a 100644 > --- a/drivers/gpu/drm/bridge/simple-bridge.c > +++ b/drivers/gpu/drm/bridge/simple-bridge.c > @@ -171,6 +171,7 @@ static int simple_bridge_probe(struct platform_device *pdev) > { > struct simple_bridge *sbridge; > struct device_node *remote; > + u32 de; > > sbridge = devm_drm_bridge_alloc(&pdev->dev, struct simple_bridge, > bridge, &simple_bridge_bridge_funcs); > @@ -212,6 +213,19 @@ static int simple_bridge_probe(struct platform_device *pdev) > sbridge->bridge.of_node = pdev->dev.of_node; > sbridge->bridge.timings = sbridge->info->timings; > > + if (!sbridge->bridge.timings && > + !of_property_read_u32(pdev->dev.of_node, "data-enable-active", &de)) { > + struct drm_bridge_timings *timings; > + > + timings = devm_kzalloc(&pdev->dev, sizeof(*timings), GFP_KERNEL); > + if (!timings) > + return -ENOMEM; > + > + timings->input_bus_flags = de ? DRM_BUS_FLAG_DE_HIGH : > + DRM_BUS_FLAG_DE_LOW; > + sbridge->bridge.timings = timings; > + } > + > return devm_drm_bridge_add(&pdev->dev, &sbridge->bridge); > } >