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TMDSEVM437X: Processors forum 1280 x 800 24-bit RGB display

Part Number: TMDSEVM437X
Other Parts Discussed in Thread: AM4378, AM4372

ttps://e2e.ti.com/support/processors/f/791/t/842003

Please refer to the above link on the same question. We are wondering if there is a continuation of the above referenced support Q&A. The support staff said they will check with their driver expert, but stopped there with no further information.

We have a custom MCU board largely derived from the TI AM4378 EVM, with the exception of a larger 1280 x 800 x 24-bit RGB display. We would like to modify the software driver or boot parameters to drive the 1280 x 800 24-bit RGB LCD.

From panel-simple.c,  we found the timing of the LCD that comes with the TI 4378 EVM: 

static const struct drm_display_mode osddisplays_osd070t1718_19ts_mode  = {

               .clock = 33000,

               .hdisplay = 800,

               .hsync_start = 800 + 210,

               .hsync_end = 800 + 210 + 30,

               .htotal = 800 + 210 + 30 + 16,

               .vdisplay = 480,

               .vsync_start = 480 + 22,

               .vsync_end = 480 + 22 + 13,

               .vtotal = 480 + 22 + 13 + 10,

               .flags = DRM_MODE_FLAG_NVSYNC | DRM_MODE_FLAG_NHSYNC,

};

 We are able to verify the Pixel Clock = 33 MHz , Hsync = 42 KHz and Vsync = 81 Hz coming out from our board, suggesting that the video output are operating at the factory default timing conditions. 

We would like to interface to a larger panel: AUO_G121 panel with 1280 x 800 x 24-bit RGB:

From the Panel-Simple.c code, we are able to identify our LCD:

static const struct drm_display_mode auo_g121ean01_mode = {

       .clock = 66700,

       .hdisplay = 1280,

       .hsync_start = 1280 + 58,

       .hsync_end = 1280 + 58 + 8,

       .htotal = 1280 + 58 + 8 + 70,

       .vdisplay = 800,

       .vsync_start = 800 + 6,

       .vsync_end = 800 + 6 + 4,

       .vtotal = 800 + 6 + 4 + 10,

   

Please advise, or point to some references, on how we can modify the TI 4387 SDK settings, re-compile, to drive this LCD.

Thank you!

Lim

  • Hello Lim,

    I am wondering if you could please refer to the second page of the linked thread. Here is the comment that I added: "Please review Advisory 14 in our AM437x silicon errata. Due to the limitation, we have added the following code in our arch/arm/boot/dts/am4372.dtsi file: "max-memory-bandwidth = <230000000>;". Based on your system design, please feel free to increase the bandwidth or remove the bandwidth."

    Regards,
    Krunal