[android-porting] New Display Porting

Discussion:

Elif Kaplan

2018-10-18 15:39:55 UTC

Hi All!

I am working with Qualcomm Snapdragon820 Board and try to port a new
display. My board is APS8096 Dev Board with Android 8.1 on it.
There is a Display Porting Guide by Qualcomm however for Snapdragon410.
Still very useful, easy to adapt for SnapD.820.

Still there are things that make me confuse :

*1.* Display/ Panel / Display controller ... They , all , are used
interchangeably or in a confusing way.Not only in the guide but in some
other document by other vendors also .
As I understand from the point of hardware
Display = Panel + Display controller + Backlight Module (opt) + Touch
screen controller(opt)
Is it right ? Are they also mentioned with these names in the
software-level /AOSP Level ? Is there a standart naming convention i have
missed or am I right to be confused ?

*2*. *The main question* : *how to port display controller and touch
contrtoller *

It is clear that how panel settings (resolution ,color depth etc..) are
imported/introduced to the system (via device tree and header for
bootloader) .
However , also related to the first question , there is no clue how *display
controller* or *touch controller* (it is relativly reasonable not to be
mentioned while it is not a mandatory part of display.) should be ported .

I have dived into the device trees and the kernel for existing display
related setting and find some entries and drivers for display controller
and also touch controller.
They shoud be also introduced to the system , right ?

Any clue would be appreciated .

Thanks and Regards ,
Elif

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Tranphong Vu

2018-10-18 16:29:28 UTC

Permalink

Hi.
Base on my knowledge I donât know why you want to port display controller.
It fits to snapdragon soc. about touch controller it bases on the
peripheral interface that you connect your touch controller to soc. you
only need to integrate the touch controller driver to your android bsp.

Post by Elif Kaplan
Hi All!
I am working with Qualcomm Snapdragon820 Board and try to port a new
display. My board is APS8096 Dev Board with Android 8.1 on it.
There is a Display Porting Guide by Qualcomm however for Snapdragon410.
Still very useful, easy to adapt for SnapD.820.
*1.* Display/ Panel / Display controller ... They , all , are used
interchangeably or in a confusing way.Not only in the guide but in some
other document by other vendors also .
As I understand from the point of hardware
Display = Panel + Display controller + Backlight Module (opt) + Touch
screen controller(opt)
Is it right ? Are they also mentioned with these names in the
software-level /AOSP Level ? Is there a standart naming convention i have
missed or am I right to be confused ?
*2*. *The main question* : *how to port display controller and touch
contrtoller *
It is clear that how panel settings (resolution ,color depth etc..) are
imported/introduced to the system (via device tree and header for
bootloader) .
However , also related to the first question , there is no clue how *display
controller* or *touch controller* (it is relativly reasonable not to be
mentioned while it is not a mandatory part of display.) should be ported .
I have dived into the device trees and the kernel for existing display
related setting and find some entries and drivers for display controller
and also touch controller.
They shoud be also introduced to the system , right ?
Any clue would be appreciated .
Thanks and Regards ,
Elif
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Elif Kaplan

2018-10-20 10:46:01 UTC

Permalink

Thanks for your reply .

Would you be kind to answer the first question if you have also hardware
background.
Because that is the key point.And that is why i ask the second one.
SoC has dsi controller , right ?
is it not right that ,for instance, an 5" TFT-LCD Display with MIPI DSI
interface comes with a driver IC in it ?

Under the code (in include folder of bootloder) there are files like
: panel_hx8379a_truly_fwvga_video.h
It does not point a trully panel with a himax driver chip on it ?

Our display supplier sent us a bunch of datasheets which include a himax
driver chip and touch controller beside the panel infos.
What would you think if you were me in that case ?
A display module with panel and controllers( display and touch ) integrated
in it ?or what else ?

If it is the case , then another question comes up : IF there is a
display driver chip on SoC and also in my display ,
then how can one bypass/deactivate the existing one and port the new one ?
Same as panel via device tree and bootloader changes or something else
should be done ?

Thanks in advance
Regards
Elif

Post by Tranphong Vu
Hi.
Base on my knowledge I donât know why you want to port display controller.
It fits to snapdragon soc. about touch controller it bases on the
peripheral interface that you connect your touch controller to soc. you
only need to integrate the touch controller driver to your android bsp.

Elif Kaplan

2018-10-25 13:03:25 UTC

Permalink

By mistake I antwortet via my email not through forum.In order others to
benefit i am sending here Tramphong Vu's and my reponses.

*Answer by Tranphong Vu on 19th Oct*

HI,
for your first question.
Display = Panel + Display controller + Backlight Module (opt) + Touch
screen controller(opt)

Post by Elif Kaplan

it is right for all design that i have met.

"SoC has dsi controller , right ?
is it not right that ,for instance, an 5" TFT-LCD Display with MIPI DSI
interface comes with a driver IC in it ?"
SOC has display controller, it not only has interface for DSI panel but
also other standard like HDMI, VGA, Display port. It depends on the your
SOC.
but may be your panel does not connect to SOC display controller. It bases
on your board design so I think you should check your board's schematic.
You would know how your display panel connect to your SOC. i think it will
connect to your SOC display controller. About the other questions, it bases
on the SOC that you are using and how your board's design so i don't have
answers for them.

*Reply by Elif (Me) at 20th Oct:*

Hello Tranphong Vu ,
I could manage to reach an old Qualcomm expert via a forum and he clarified
the problem.
I share the conclusion as a short summory of mine :
As we agree on : each display has a controller/driver chip on it.
But it is not possible that each different driver chip (or called
controller chip) fits on the SoC . SoC has a controller chip for the
interface of course (like MIPI DSI controller ).
Still ,no matter what kind of a SoC is it, the driver chip on the display
should be intoduced to the system (via device tree and driver files etc.)

For your infrormation
And thanks again for replying .

Best Regards
Elif

Post by Elif Kaplan
Thanks for your reply .
Would you be kind to answer the first question if you have also hardware
background.
Because that is the key point.And that is why i ask the second one.
SoC has dsi controller , right ?
is it not right that ,for instance, an 5" TFT-LCD Display with MIPI DSI
interface comes with a driver IC in it ?
Under the code (in include folder of bootloder) there are files like
: panel_hx8379a_truly_fwvga_video.h
It does not point a trully panel with a himax driver chip on it ?
Our display supplier sent us a bunch of datasheets which include a himax
driver chip and touch controller beside the panel infos.
What would you think if you were me in that case ?
A display module with panel and controllers( display and touch )
integrated in it ?or what else ?
If it is the case , then another question comes up : IF there is a
display driver chip on SoC and also in my display ,
then how can one bypass/deactivate the existing one and port the new one
?
Same as panel via device tree and bootloader changes or something else
should be done ?
Thanks in advance
Regards
Elif

Hi.
Base on my knowledge I donât know why you want to port display
controller. It fits to snapdragon soc. about touch controller it bases on
the peripheral interface that you connect your touch controller to soc. you
only need to integrate the touch controller driver to your android bsp.

Post by Elif Kaplan
Hi All!
I am working with Qualcomm Snapdragon820 Board and try to port a new
display. My board is APS8096 Dev Board with Android 8.1 on it.
There is a Display Porting Guide by Qualcomm however for Snapdragon410.
Still very useful, easy to adapt for SnapD.820.
*1.* Display/ Panel / Display controller ... They , all , are used
interchangeably or in a confusing way.Not only in the guide but in some
other document by other vendors also .
As I understand from the point of hardware
Display = Panel + Display controller + Backlight Module (opt) + Touch
screen controller(opt)
Is it right ? Are they also mentioned with these names in the
software-level /AOSP Level ? Is there a standart naming convention i have
missed or am I right to be confused ?
*2*. *The main question* : *how to port display controller and touch
contrtoller *
It is clear that how panel settings (resolution ,color depth etc..) are
imported/introduced to the system (via device tree and header for
bootloader) .
However , also related to the first question , there is no clue how *display
controller* or *touch controller* (it is relativly reasonable not to be
mentioned while it is not a mandatory part of display.) should be ported .
I have dived into the device trees and the kernel for existing display
related setting and find some entries and drivers for display controller
and also touch controller.
They shoud be also introduced to the system , right ?
Any clue would be appreciated .
Thanks and Regards ,
Elif
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chirag vaghela

2018-10-19 16:39:23 UTC

Permalink

Hello Elif,

No need to worry about display controller. You just need to check your
display interface with host. and check driver is available. if not then you
need to integrate it. port proper display device tree node in dtsi file and
create display.dtsi file. same you need to check for touch. thats it.

--------
Regards,
*Chirag Vaghela*

Elif Kaplan

2018-10-20 11:04:39 UTC

Permalink

Hello Chirag ,

Thanks for the reply.
I do not worry ;) and did not expect to hear more (then adding driver and
device tree).
It means there are still changes , not worry about ;) but i should take
care of .

Thanks and best regards
Elif

Post by chirag vaghela
Hello Elif,
No need to worry about display controller. You just need to check your
display interface with host. and check driver is available. if not then you
need to integrate it. port proper display device tree node in dtsi file and
create display.dtsi file. same you need to check for touch. thats it.
--------
Regards,
*Chirag Vaghela*