imx8mm: how to dynamically change video_pll1?

キャンセル
次の結果を表示 
表示  限定  | 次の代わりに検索 
もしかして: 

imx8mm: how to dynamically change video_pll1?

498件の閲覧回数
adevries
Contributor V

Hello,

I have an imx8m mini that I am trying to make output different HDMI resolutions. The lcdif_pixel clock is sourced from video_pll1, which is currently 594 MHz. However, I want to output at a resolution that uses a 65 MHz pixel clock. When I try to switch to this resolution, I don't get any output, and I think that's because the lcdif_pixel clock is 66 MHz, not 65 MHz. Given the parent clock of 594 MHz, 66 MHz is probably the closest it can get to 65, but why won't video_pll1 simply change from 594 to 650 MHz? The clock rate is defined in the clk-imx8mm.c driver file. Why won't the PLL switch to 650 MHz?

Thanks

ラベル(1)
タグ(4)
0 件の賞賛
2 返答(返信)

483件の閲覧回数
Zhiming_Liu
NXP TechSupport
NXP TechSupport

How do you change the code for 65Mhz pixel clk?

0 件の賞賛

476件の閲覧回数
adevries
Contributor V

Hi Qmiller,

I have been using the linux modetest utility to test different resolutions. For example, "modetest -M imx-drm -s 35[at]33:1920x1080-60"  outputs a test pattern at 1920x1080 at 60Hz. That needs a pixel clock of 148.5 MHz. However, when I run "modetest -M imx-drm -s 35[at]33:1024x768-60", I don't get any test pattern being output, and the lcdif_pixel clock is 66 MHz instead of 65 MHz.

0 件の賞賛