yes seems this is correct as from Table 18-3. System Clocks, Gating, and Override i.MX6DQ Reference Manual isfrclk has clock source as video_27m_clk_root and it has source as "pll3_pfd1_540m" according to Figure 18-3. Clock Tree - Part 2, VIDEO_27M_CLK_ROOT, https://www.nxp.com/docs/en/reference-manual/IMX6DQRM.pdf
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