Question about clock configuration for dual-display.

[simmisxu]

Hi,

I have a case which needs to support dual-display.

The primary display: RGB port output, 1280*720, 60Hz, on ipu1.

The secondary display: LVDS port output, 800*480, 60Hz, on ipu0.

There are 2 clock configurations:

1、pll5 for primary, while pll2 for secondary.

     In this case, the expected frequency is 33.264M (800*480, 60Hz), so the PLL2_PFD0 should be 33.263*7=232.8M. But the actual pll2 clock we can configure is 271.5M.

2、pll2 for primary, while pll5 for secondary.

      I can get the correct clocks in this case. The problem is :

      By changing pll5_video_main_clk to 232M (from original 650M), i can get excepted clocks. The problem is :

     pll5_video_main_clk is also source for other ip modules like, ipu1_di_clk.

     I wonder whether the new configuration has bad impacts on other modules.

Thanks,

Simmis.

[igorpadykov]

Hi Simmis

one can check if this clock is used anywhere else checking sources in clk-imx6q.c

linux/clk-imx6q.c at master · torvalds/linux · GitHub

or dump linux clock tree :

[meta-fsl-arm,03/12] imx-test: Stop installing clocks.sh in MX6 - Patchwork

Best regards

igor

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