ubuntu-phone team mailing list archive

[Simos Xenitellis <simos.lists@xxxxxxxxxxxxxx>]

On Mon, Aug 24, 2015 at 5:52 PM, sturmflut <sturmflut@xxxxxxxxxxxxxx> wrote:
> On 24.08.2015 13:32, Oliver Grawert wrote:
>
>> afaik the hardware doesnt support MHL ... and even if it would, the
>> binary PVR driver most likely wouldn't support it.
>
>
> Short answer:
>
> The MX4 kernel sets "MTK_INTERNAL_MHL_SUPPORT=no", nobody ever got it
> working, and I've found no indication that the device has the necessary
> hardware.
>
>
> Long answer:
>
> Embedded SoCs usually don't directly support external displays attached
> via MHL, SlimPort or HDMI for two reasons:
>
> - They may support only a single display, and the "usual" internal
> display modules do not speak MHL/SlimPort/HDMI.
>
> - They may support multiple displays, but it is up to the device
> manufacturer to choose which port outputs signals conforming to which
> standard.
>
> So everybody goes the safe way and lets their SoC output signals
> conforming to the MIPI Alliance standards [1]. Those can be used to talk
> to internal displays, or can be converted to just about everything else.
>
> In the case of the MT6595 SoC used in the Meizu MX4, the SoC supports
> two MIPI SPI ports for up to two internal displays, and one MIPI DPI
> port for an external display at up to 1080p 3D resolution. The PowerVR
> driver supports this, to it the external display is just another MIPI port.
>
> The MIPI port signals have to be converted to MHL by a separate MHL
> Bridge chip inside the device, and then later to HDMI by a second
> converter chip in the cable. It can be done, the MediaTek kernel sources
> contain drivers for some MHL Bridge chips, but as a matter of fact about
> 95% of the MediaTek-based devices on the market do not have an MHL
> Bridge chip. This can e.g. be seen when looking at how few bq devices
> are listed as being compatible with their own MHL cable [2].
>
> As far as I can tell, the MX4 also doesn't have the Bridge chip.
>
>
> cheers,
> Simon
>
> [1] http://mipi.org/
>
> [2] http://store.bq.com/es/cable-mhl-hdmi
>

Indeed, it looks like MHL may not be supported in terms of hardware on
the phone.
I think it would the "MHL transmitter" that may be missing, as the
"MHL Bridge chip" is the hardware to put on an HDTV, etc.

There are unofficial pages that hint to MHL support,
1. http://www.gsmarena.com/meizu_mx4-6627.php ("MHL TV-out").
2. http://docteur-gsm.com/en/meizu-mx4/225124-meizu-mx4-mhl-hdmi-adapter.html
(They are selling a cable).

However, at http://www.meizu.com/en/products/mx4/spec.html there is no
mention about TV-out/MHL.
In addition, http://www.meetmhl.com/devices.aspx?tid=1 lists the
MHL-compatible devices
and it is the official website for the MHL Consortium.
While it lists two earlier phones by Meizu, it does not list the MX4.
There are videos on Youtube that show the
old Meizu MX (dual core Exynos SoC) that supports MHL.

It is possible that Meizu decided not to enable MHL in software to
avoid royalties, etc.

If someone can do the teardown of the hardware - there are several
videos on Youtube for this,
they can visually inspect whether there is an MHL transmitter chip.
For example, the Sil8240 is shown in this phone at
http://www.slideshare.net/jjwu6266/introducing-samsung-galaxy-s-iv (page 60).

Simos