[DRM] Using DCSS as input source can support 60FPS, but LCDIF can NOT

[KyleChang]

Based on Case Number: 00560728, we do an experiment to clarify why 1920*1080@60 can't work.

1) Using DCSS as input source

2) 1920*1080@60FPS(pixel clock=146025000)

static const struct display_timing  = {

.pixelclock = { 146025000, 146025000, 146025000 },

.hactive = { 1920, 1920, 1920 },

.hfront_porch = { 72, 72, 72 },

.hback_porch = { 136, 136, 136 },

.hsync_len = { 32, 32, 32 },

.vactive = { 1080, 1080, 1080 },

.vfront_porch = { 4, 4, 4 },

.vback_porch = { 36, 36, 36 },

.vsync_len = { 5, 5, 5 },

.flags = DISPLAY_FLAGS_DE_HIGH,

};

Based on item(1)(2), DCSS can support 1920*1080@60FPS.

But we just change input source from DCSS to LCDIF, get error message [drm] Cannot find any crtc or sizes.

[Kavya_2025]

Hi @KyleChang,

I am working on DCSS(trying to use for upscaling the input data). But, I'm getting the same error/dmesg for DCSS. i.e "can't find any crtc or sizes". 

 I wanted to know did your problem gets solved, If yes, I would like to know how did you solve your issue. What can be done?

Regards,

Kavya

[KyleChang]

Which board are you using? NXP reference board or the board you design yourself?

=>i.MX8MQ platform(android-11.0.0_2.2.0, Linux 5.10.35 kernel), and the board we design ourselves.

Maybe we can focus on LCDIF display controller first.
On our design board, we also implement i.MX8MQ+GM8775C(DSI to LVDS bridge).

1)1920*1080@30FPS & using LCDIF as input source
LVDS panel works.

2)1920*1080@60FPS(pixel clock=146025000) & using LCDIF as input source
get error message: "mxsfb 30320000.lcd-controller: [drm] Cannot find any crtc or sizes"

Attached is LCDIF_146M_60FPS.log

3)1920*1080@60FPS(pixel clock=146025000) & using DCSS as input source
LVDS panel works.

Attached is DCSS_146M_60FPS.log

[Rita_Wang]

I help create new case for it 00575007, our engineer will give update to you.

Wish you have a nice day

[Rita_Wang]

Which board are you using? NXP reference board or the board you design yourself?