On Wed, Nov 7, 2018 at 2:41 PM Andrzej Hajda <a.hajda@xxxxxxxxxxx> wrote: > > On 06.11.2018 19:08, Jagan Teki wrote: > > On Wed, Oct 31, 2018 at 2:45 PM Andrzej Hajda <a.hajda@xxxxxxxxxxx> wrote: > >> On 31.10.2018 09:58, Chen-Yu Tsai wrote: > >>> On Wed, Oct 31, 2018 at 4:53 PM Andrzej Hajda <a.hajda@xxxxxxxxxxx> wrote: > >>>> On 26.10.2018 16:43, Jagan Teki wrote: > >>>>> Bananapi S070WV20-CT16 ICN6211 is 800x480, 4-lane MIPI-DSI to RGB > >>>>> bridge panel, which is available on same PCB with 24-bit RGB interface. > >>>>> > >>>>> So, this patch adds DSI specific binding details on existing > >>>>> dt-bindings file. > >>>>> > >>>>> Signed-off-by: Jagan Teki <jagan@xxxxxxxxxxxxxxxxxxxx> > >>>>> --- > >>>>> Changes for v3: > >>>>> - Use existing binding doc and update dsi details > >>>>> Changes for v2: > >>>>> - none > >>>>> > >>>>> .../display/panel/bananapi,s070wv20-ct16.txt | 31 +++++++++++++++++-- > >>>>> 1 file changed, 29 insertions(+), 2 deletions(-) > >>>>> > >>>>> diff --git a/Documentation/devicetree/bindings/display/panel/bananapi,s070wv20-ct16.txt b/Documentation/devicetree/bindings/display/panel/bananapi,s070wv20-ct16.txt > >>>>> index 35bc0c839f49..b7855dc7c66f 100644 > >>>>> --- a/Documentation/devicetree/bindings/display/panel/bananapi,s070wv20-ct16.txt > >>>>> +++ b/Documentation/devicetree/bindings/display/panel/bananapi,s070wv20-ct16.txt > >>>>> @@ -1,12 +1,39 @@ > >>>>> Banana Pi 7" (S070WV20-CT16) TFT LCD Panel > >>>>> > >>>>> +S070WV20-CT16 is 7" 800x480 panel connected through a 24-bit RGB interface. > >>>>> + > >>>>> +Depending on the variant, the PCB attached to the panel module either > >>>>> +supports DSI, or DSI + 24-bit RGB. DSI is converted to 24-bit RGB via > >>>>> +an onboard ICN6211 MIPI DSI - RGB bridge chip, then fed to the panel > >>>>> +itself > >>>> As I understand this is display board, which contains 'pure' RGB panel > >>>> S070WV20-CT16 and optionally ICN6211 DSI->RGB bridge. > >>>> These are separate devices, just connected by vendor to simplify its > >>>> assembly. Why don't you create then bridge driver for ICN6211 and RGB > >>>> panel driver for S070WV20-CT16 - it looks more generic. > >>>> Then you can describe both in dts and voila. > >>>> Creating drivers for every combo of devices (panel + bridge), just > >>>> because some vendor sells them together seems incorrect - we have > >>>> devicetree for it. > >>> Rob suggested this, and also the opposite: using the same > >>> "bananapi,s070wv20-ct16" > >>> compatible string for both types of connections, and have the driver deal with > >>> detecting the bus type. > >>> > >>> The thing about the bridge chip is that there's no available datasheet that > >>> describes all the parts of the init sequence, in fact none at all. I managed > >>> to work out some bits, but the others remain a mystery and must be hard-coded > >>> to match the panel. That would work against having a generic bridge driver. > >> > >> But it is common for many chips - 1st version of the driver is developed > >> on one platform and it supports only one configuration, if next platform > >> with the same cheap appears the driver is augmented if necessary. > > At-least few of the commands from panel initialization code, the > > respective opcode data values are based on panel timings and even > > clock value is different in DSI. I think it look hard to try bridge > > driver for these restrictions, do you have any suggestions? > > > Where do you see an issue? Since panel is RGB it should have no > initialization sequence (beside regulator/gpio power on/off), so the > only thing to do is to figure out which regulators/gpios belongs to > which component - with publicly available specs it should be doable. > > The whole initialization sequence is for the bridge, so you put it into > bridge driver, for starters it can be hardcoded. Yes, I understand we can move regulators/gpio setup separately and though we hardcode the init sequence there is difference in clock for DSI(which I mentioned in previous mail). DSI panel can't work with clock used by RGB panel-simple. > > Then you can: > > 1. Try to find other users of this ICN6211 chip and compare > initialization sequences to guess purpose of registers. > > 2. Try to get specs of the chip (ask vendor, distributor, grep Internet). As we mentioned (even Chen-Yu), we are unable to find the proper spec for this panel, all we taken reference from AW BSP code. > > 3. Do nothing - if there will be other users of the bridge they will do > this work. Don't know how we can go with generic bridge driver irrespective of these particular wrinkles, let me know if you have any suggestions.
