Hi Marek, (CC'ing Mark Brown) On Friday 11 Aug 2017 09:00:00 Marek Szyprowski wrote: > On 2017-08-10 16:51, Laurent Pinchart wrote: > > On Friday 04 Aug 2017 08:55:55 Marek Szyprowski wrote: > >> Hi Laurent, > >> > >> Thanks for your detailed comments. Maciej resurrected some orphaned code, > >> which is still useful today (Tomasz has left Samsung a few years ago). > >> I'm not sure we will be able to answer all your questions without deep > >> investigation, especially about the driver operation details, but we > >> will try. > > > > Thank you. > > > >> On 2017-08-03 12:24, Laurent Pinchart wrote: > >>> On Thursday 03 Aug 2017 09:45:22 Maciej Purski wrote: > >>>> SiI9234 transmitter converts eTMDS/HDMI signal to MHL 1.0. > >>>> It is controlled via I2C bus. Its interaction with other > >>>> devices in video pipeline is performed mainly on HW level. > >>>> The only interaction it does on device driver level is > >>>> filtering-out unsupported video modes, it exposes drm_bridge > >>>> interface to perform this operation. > >>>> > >>>> This patch is based on the code refactored by Tomasz Stanislawski > >>>> <t.stanislaws@xxxxxxxxxxx>, which was initially developed by: > >>>> Adam Hampson <ahampson@xxxxxxxxxxxxxxx> > >>>> Erik Gilling <konkers@xxxxxxxxxxx> > >>>> Shankar Bandal <shankar.b@xxxxxxxxxxx> > >>>> Dharam Kumar <dharam.kr@xxxxxxxxxxx> > >>>> > >>>> Signed-off-by: Maciej Purski <m.purski@xxxxxxxxxxx> > >>>> --- > >>>> > >>>> .../devicetree/bindings/display/bridge/sii9234.txt | 20 + > >>>> drivers/gpu/drm/bridge/Kconfig | 8 + > >>>> drivers/gpu/drm/bridge/Makefile | 1 + > >>>> drivers/gpu/drm/bridge/sii9234.c | 1019 ++++++++++ > >>>> 4 files changed, 1048 insertions(+) > >>>> create mode 100644 > >>>> > >>>> Documentation/devicetree/bindings/display/bridge/sii9234.txt create > >>>> mode > >>>> 100644 drivers/gpu/drm/bridge/sii9234.c > >>>> > >>>> diff --git > >>>> a/Documentation/devicetree/bindings/display/bridge/sii9234.txt > >>>> b/Documentation/devicetree/bindings/display/bridge/sii9234.txt new file > >>>> mode 100644 > >>>> index 0000000..2cdf286 > >>>> --- /dev/null > >>>> +++ b/Documentation/devicetree/bindings/display/bridge/sii9234.txt > >>> > >>> DT reviewers might ask you to submit DT bindings as a separate patch. > >>> > >>>> @@ -0,0 +1,20 @@ > >>>> +SiI9234 Mobile HD Link Transmitter > >>>> + > >>>> +Required properties: > >>>> +- compatible : "sil,sii9234". > >>>> +- reg : I2C address for TPI interface, use 0x39 > >>>> +- vcc-supply : regulator that supplies the chip > >>> > >>> Is there a single power supply only ? Transceivers usually have at least > >>> one digital and one analog power supply. > >> > >> Acording to the schematic there are four power supplies used for SII9234 > >> MHL chip in Trats2 board: VSIL_1.2A, VSIL_1.2C, VCC_3.3V_MHL and > >> VCC_1.8V_MHL. First two are derived directly from VSIL_1.2 signal, which > >> is modeled as a fixed regulator. The latter two are derived directly from > >> VBAT using some level converter, which is controlled by the same GPIO pin > >> as VSIL fixed regulator. Any idea how this should be represented better > >> in device tree instead of having single vcc-supply? > > > > Without access to the documentation I can only guess, but it looks like > > VSIL_1.2A and VSIL_1.2C are supposed to be powered from the same power > > supply rail, possibly with different filters. I think they can be grouped > > together from a DT binding point of view. The last two supplies seem > > independent. We should thus probably model this as three separate > > supplies. > > Okay, I see no problem adding support for all those three supplies, but > I was wondering how to model them in the device tree, because from the > software perspective ALL power supplies needed by this chip are enabled by a > single GPIO line switch. > > I see 3 possible solutions: > 1. Keep only single vcc supply for now and use fixed gpio regulator for it > as a provider. Add a comment that it fact it provides 3 different power > signals. > 2. Extend fixed gpio regulator driver and bindings so it will be possible to > have more than one fixed regulator controlled by the same gpio pin. > 3. Model VCC_3.3V_MHL and VCC_1.8V_MHL providers as "vctrl-regulator" and > use this VSIL_1.2 as control voltage for them. > > Which one do you prefer? 2 would be best I think, but that's more work. Mark, what do you think ? > > It would be useful to check in the SII9234 datasheet what power sequence > > the chip expects. Is there any chance you could find that document ? > > We have access only to the parts of the SII9234 documentation now and > there is no > such information there. > > >>>> +- interrupts, interrupt-parent: interrupt specifier of INT pin > >>>> +- reset-gpios: gpio specifier of RESET pin > >>> > >>> Is this mandatory to connect the reset pin to the SoC ? > >> > >> IMHO yes, the chip has to be reset during the initialization procedure > >> and doesn't work properly without reset. > > > > OK, I have no issue making the property mandatory then. > > Best regards -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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