topic Re: imx8qxp 24bpp framebuffer parallel rgb in i.MX Processors

imx8qxp 24bpp framebuffer parallel rgb

TKayO — Fri, 27 Aug 2021 09:27:25 GMT

Hello,

I'm trying to setup 720p performance test for parellel rgb display.

Which is documented on the reference manual as below

" The Parallel Display Interface (LCD Interface), which supports 720p60 display, is
located in the Audio-DMA (ADMA) Subsystem (please see the ADMA Subsystem for
details on the LCD Interface (LCDIF) block)."

It's because, 800x600x32bpp parallel rgb display works well with gstreamer video playback

but resolution increased to 1024x768, video flickers while playing mp4 video.

So, I'm assuming maybe the 32bpp format overhead makes this problem,

That's why I need 24 or 16 bpp setting.

So, I made some changed on

drivers\gpu\drm\mxsfb\mxsfb_drv.c :: mxsfb_probe()

drm_fbdev_generic_setup(drm, 32); --> drm_fbdev_generic_setup(drm, 16);

but, although the changes above,

drivers\gpu\drm\mxsfb\mxsfb_crtc.c :: mxsfb_set_pixel_fmt()

this function make fb format "DRM_FORMAT_XRGB8888", XR24.

My purpose is to setup 24bpp format but

drivers\gpu\drm\mxsfb\mxsfb_crtc.c :: mxsfb_set_pixel_fmt() <-- this function does not handle 24bpp case. it handles 24bpp case as error.

Q. How can I setup my framebuffer format as 24bit RGB888?

Re: imx8qxp 24bpp framebuffer parallel rgb

igorpadykov — Fri, 27 Aug 2021 11:50:22 GMT

Hi WOOSEOK

one can try to change format with dts "fsl,interface-pix-fmt" property in

https://source.codeaurora.org/external/imx/linux-imx/tree/arch/arm64/boot/dts/freescale/imx8x-mek-dpu-lcdif.dtsi?h=lf-5.10.y

driver function imx_lmuxd_bind()

https://source.codeaurora.org/external/imx/linux-imx/tree/drivers/gpu/drm/imx/lcdif-mux-display.c?h=lf-5.10.y

Best regards
igor

Re: imx8qxp 24bpp framebuffer parallel rgb

TKayO — Sat, 28 Aug 2021 08:25:44 GMT

Hi, Igor.

Thank you for your concern.

Your reply is about setting "MEDIA_BUS_FMT...",

And what I asked is about "DRM_FORMAT_... " and I think these two are very different.

Re: imx8qxp 24bpp framebuffer parallel rgb

TKayO — Tue, 31 Aug 2021 02:37:18 GMT

@igorpadykov

Any update or recommend?