unl0kr: optimize the main loop

Testing on Librem 5 (aarch64, unl0kr is compiled with -Dbuildtype=release and used with default configuration and a physical keyboard):

Experiment	unl0kr, master branch	unl0kr, main_loop branch
Start unl0kr, wait for 1 min, press Enter	real 1m0,030s user 0m0,442s sys 0m0,336s	real 1m0,074s user 0m0,331s sys 0m0,170s
Start unl0kr, continuously press "1" on the keyboard for 1 min, press Enter	real 1m0,079s user 0m1,902s sys 0m0,323s	real 1m0,547s user 0m1,830s sys 0m0,168s

@cherrypicker Did you make some measurements with it? It would be nice to test on different phones.

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• e4e3d37e - unl0kr: optimize the main loop

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Thanks for contributing this and interesting find! The main loop has gone through a few very different implementations over time but I have never actually timed it as it didn't seem critical. I'm happy to land this though given that the new code isn't much more complicated than the old and shaves off some processing time.

We can test it on a few more devices as part of the pmaports MR once we make another release.

Could you add a changelog entry, ideally thanking yourself for the contribution?

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• e4e3d37e...3196e47d - 2 commits from branch postmarketOS:master
• 558e9465 - unl0kr: optimize the main loop

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• 7e4590ee - unl0kr: optimize the main loop

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We can also optimize lv_delay_ms(). The generic version just do useless work in a cycle until the time reached. But seems this function is not used often. What do you think?

$ grep -rF 'lv_delay_ms'
drivers/display/lcd/lv_lcd_generic_mipi.c:                lv_delay_ms((uint32_t)(num) * 10);
drivers/display/lcd/lv_lcd_generic_mipi.c:    lv_delay_ms(10);
drivers/display/lcd/lv_lcd_generic_mipi.c:    lv_delay_ms(200);
drivers/display/lcd/lv_lcd_generic_mipi.c:    lv_delay_ms(300);
tick/lv_tick.h:void lv_delay_ms(uint32_t ms);
tick/lv_tick.c:void lv_delay_ms(uint32_t ms)

This would be an upstream change in LVGL then?

Nope, LVGL allows to override it with lv_delay_set_cb(). I think we should not do it now, because lv_delay_ms() is used in the MIPI display driver only, but who knows, maybe LVGL developers will add it to more places in the future releases.

Oh, I see. Ok, then lets descope this for now.

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• a89df3a0 - unl0kr: optimize the main loop

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• a89df3a0...d5838377 - 15 commits from branch postmarketOS:master
• 3613ba4e - Merge branch 'master' into 'main_loop'

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approved this merge request

mentioned in commit 18b576f2

merged

Thanks again for contributing this!