NuttX + FB device (SAMA5D2) - rendering problem/tearing

[TimJTi]

LVGL version

9.1.0

What happened?

Having moved from LVGL V8 to V9 I am seeing issues with rendering basic graphics to an 800x480 framebuffer using NuttX.

I have created a very simple screen with just a spinner, but the leading/trailing edges of the spinner "tear" with horizontal lines much of the time.

LVGL_problem.mp4

I have played around with every rendering option I can find (via Kconfig) but it is stubbornly consistent, and occurs for ARGB888 and RGB565. I am at a loss and am thinking it might be a problem with the LVGL+NuttX framebuffer implementation?

Neither V8 nor V9 use double buffering as far as I can tell, but is looks like it is almost like the rendering being done to the buffer at the same time as it is being written to the LCD. Or

LVGL demos suffer the same issue, but they didn't with V8 so I don't think its my (custom) board nor the NuttX RTOS itself (as opposed to the NuttX LVGL port)?

I have run out of ideas but am very happy to try things - I really don't want to go back to LVGL V8 given all the function name changes etc as that is a PITA!!

How to reproduce?

No response

[TimJTi]

For completeness here is (nearly) the same spinner in LVGL V8.3.3:

LVGLv8_noproblem.mp4

[liyang5945]

check your lv_port_disp_init function, has a lv_display_set_buffers... function call, wha't the last param? if LV_DISPLAY_RENDER_MODE_FULL or LV_DISPLAY_RENDER_MODE_DIRECT change it to LV_DISPLAY_RENDER_MODE_PARTIAL

[jianglianfang]

It happend to me when I enbled CONFIG_FB_UPDATE with single framebuffer mode. U can try this #6397. it may help you.