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LCD and HDMI with two different resolutions

sanjay c
Intellectual 290 points

I am using a custom board based on OMAP4460. We are using TI ICS 4.AI-1.4.

I have a LCD with resolution 480x800 [dpi]. When we connect a HDMi TV it shows a scaled version of 480x800 on 720p HDMI. I have checked this on the Blaze Board where 864x480 is scaled to 720p on the HDMI TV.

We want to get true 720p resolution on the HDMI TV without any scaling.

Has anyone tried this ? Any pointers would be helpful.

Thank you for your time.

Regards,

Sanjay 

  • 0
    Expert 1780 points

    Hi Sanjay.

    There appears to be useful information at

    http://e2e.ti.com/support/omap/f/849/p/188792/677658.aspx#677658

    and

    http://e2e.ti.com/support/omap/f/849/p/189552/680301.aspx#680301

    Regards,

        Steve

  • 0 in reply to Steve Schefter
    Intellectual 415 points

    Hi steve,

    So requirement is to display none-scaled version of 720p on HDMI. And the current implementation of SurfaceFlinger and HWC is such a way that it reads the primary display resolution and composes all UI surfaces with the resolution of primary display in our case it is 480x800.

    Once HDMI is connected it it scales the 480x800 using overlays to 720p on HDMI which does show the screen stretched.

    I have gone through the above thread it does not help me.

    To achieve this I tried a simple hack where primary display on dsscomp query returns 1280x720 as the primary display resolution but in LCD driver timings it uses 480x800. With this modification HDMI shows the true 720p. And LCD shows nothing as overlay 0 which is GFX pipeline which does not support scaling and fails.

    For this I have changed HWC to change the primary displays overlay from 0 to 1 and 1 to 2 if HDMI is not connected and when HDMI is connected overlays of HDMI and primary display are swapped with this modification I can see HDMI with true 720p but primary LCD shows the cropped image of 720p (ie 480x720) and it screen appears stretched

    It will be helpful if you could point me that I'm going in right direction or any help, if you understand my requirement and aware of how it can be done, is appreciated.

    Regards

    Anuroop

  • 0 in reply to Anuroop Jesu
    Prodigy 190 points

    Hello,

    i have a similar problem where all overlays get initialized with the primary display resolution.  

    Our requirement is to be able to support multiple display resolutions at runtime. We are ruuning JB on omap5

    On bootup, overlay0 and overlay1 (input_size and screen_width) get initialized to whatever resolution it reads from hdmi panel. Overlay0 is enabled by default and display output is fine.

    now when we disconnect the current hdmi panel and connect another hdmi panel with different resolution, overlay0 gets disabled and overlay1 gets enabled. The output_size of overlay1 gets updated to new reslution but the input_size doesnot change. As a result, the output looks stretched or shrinked because of scaling and does not show the true resolution. How do we change input_size on overlay1 to the new resolution?

    Any help would be greatly appreciated.

    Thank you,

    Aparikh