Re: [PATCH v2 2/4] drm/panel: Add driver for DJN HX83112A LCD panel

[Neil Armstrong]

On 12/01/2024 10:00, Luca Weiss wrote:
> On Thu Jan 11, 2024 at 8:05 PM CET, Linus Walleij wrote:
> > On Thu, Jan 11, 2024 at 4:28 PM Luca Weiss <luca.weiss@xxxxxxxxxxxxx> wrote:
> >
> > > In some internal documentation it says "LCD Driver IC" "HX83112A" and I
> > > don't see any reference to Truly 5P65 anywhere.
> >
> > In the Android directory I pointed to I see this file:
> > HX83112_Android_Driver/Truly_5p65_module_fw/UpdateFW.bat
> >
> > (Notice the 5p65 fw dir is *inside* the HX82112 dir)
> >
> > And in that file:
> > adb push TRULY_5P65_1080_2160_HX83112A_D01C01.bin
> > /system/etc/firmware/Himax_firmware.bin
> >
> > Clearly indicating that they are pushing a Truly 5P65 firmware into
> > the Himax display firmware directory.
> >
> > To be fair, that is the driver for the touchscreen part of HX83112A,
> > but ... Truly is a well known manufacturer of display controllers?
> >
> > But... given that you have a @fairphone.com mal address and
> > a working relationship with them, can't you just ask?
> >
> > > On their website they have this sentence:
> >
> > All OEMs want to look like everything is their own product. It is
> > business as usual.
>
> I can't tell you anything there that I don't know, sorry.
>
> > Further on the same note since I guess you have a datasheet)
> > please bring in #defines for the commands (the first byte in the
> > write sequences, for examples:
> >
> > +       mipi_dsi_dcs_write_seq(dsi, 0xbd, 0x02);
> > +       mipi_dsi_dcs_write_seq(dsi, 0xd8,
> > +                              0xaa, 0xff, 0xff, 0xff, 0xff, 0xff, 0xaa, 0xff,
> > +                              0xff, 0xff, 0xff, 0xff);
> > +       mipi_dsi_dcs_write_seq(dsi, 0xbd, 0x03);
> >
> > Clearly 0xbd is HX83112_CMD_SETREGBANK?
> > (This is easily spotted from the similar structure in the
> > existing panel-himax-hx8394.c.) So please add #defines
> > for all commands you know, especially if you have a datasheet
> > because we reviewers don't have them and "it's just magic
> > bytes" isn't very compelling. It adds a lot to understanding.
>
> Right, the register names seem to match more or less the ones from that
> driver, plus some new ones and some differently named ones. Will send a
> v3 with that.
>
> > I strongly suspect other Himax displays such as HX8394 to
> > be using a Truly controller as well, hence the similarities.
> >
> > In a datasheet for their TFT800480-84-V1-E display controller
> > Truly kept the init sequence name of void LCD_INIT_HX8290(void)
> > for example.
>
> In that datasheet (assuming I'm looking at the same one?) it says
> "Driver IC" "HX8290-A[...]" so there the display driver is manufactured
> by Himax and not Truly to my understanding. Truly is assembling together
> Driver + all the other parts that go into an LCD.
>
> For the panel used on Fairphone 4 that part is done by the company DJN.

Looking at the discussion, this seems to confirm the Display+Touch IC is HX83112A,
and Truly is the panel manufacturer and all assembled by DJN, so IMHO the initial driver is right.

Perhaps the compatible should be djn,hx83112a-truly-5p65 to reflect that ?

Neil

> Regards
> Luca
>
> > Yours,
> > Linus Walleij