MobileRead Forums - View Single Post - PW4 com.lab126 command for invert black and white screen

NiLuJe · 03-27-2020, 12:55 AM

I naively read that as simply swapping the epdc to the inverted palette like the K4, which simply involves an ioctl to set the fb's vinfo grayscale field to 2 (GRAYSCALE_8BIT_INVERTED), but I don't have the device either

.

(The ioctl approach *should* work everywhere, though, but I don't remember testing this all that much.
[EDIT: Even works properly on a Kobo, where the fb cmap is completely bogus]
[EDIT²: Which makes sense, as it turns out that in this case, the epdc driver simply enforces the EPDC_FLAG_ENABLE_INVERSION flag

]
TL;DR: Which means that, yes, this (ioctl) will enable the bare-minimum HW nightmode automagically everywhere without having to handle it on a per-refresh basis. No fancy waveform modes or fl trickery, though (unless ligl bases its decisions on checking the grayscale flag's value).).

EDIT: On the other hand, on Zelda/Rex, there *is* an MXCFB_SET_NIGHTMODE ioctl. I'm not *quite* sure how it's supposed to work (especially since it doesn't appear to have anything to do with the mxcfb_nightmode_ctrl struct, which appears to be handled by the fl driver, on Zelda, at least). And it also doesn't appear to be plugged into anything in the driver code?
I do have strace builds around for Zelda/Rex if someone's curious (the one shipped w/ USBNet will prooobably segfault on Zelda/Rex).

03-27-2020, 12:55 AM	#6
NiLuJe BLAM! Posts: 13,506 Karma: 26047202 Join Date: Jun 2010 Location: Paris, France Device: Kindle 2i, 3g, 4, 5w, PW, PW2, PW5; Kobo H2O, Forma, Elipsa, Sage, C2E	I naively read that as simply swapping the epdc to the inverted palette like the K4, which simply involves an ioctl to set the fb's vinfo grayscale field to 2 (GRAYSCALE_8BIT_INVERTED), but I don't have the device either . (The ioctl approach should work everywhere, though, but I don't remember testing this all that much. [EDIT: Even works properly on a Kobo, where the fb cmap is completely bogus] [EDIT²: Which makes sense, as it turns out that in this case, the epdc driver simply enforces the EPDC_FLAG_ENABLE_INVERSION flag ] TL;DR: Which means that, yes, this (ioctl) will enable the bare-minimum HW nightmode automagically everywhere without having to handle it on a per-refresh basis. No fancy waveform modes or fl trickery, though (unless ligl bases its decisions on checking the grayscale flag's value).). EDIT: On the other hand, on Zelda/Rex, there is an MXCFB_SET_NIGHTMODE ioctl. I'm not quite sure how it's supposed to work (especially since it doesn't appear to have anything to do with the mxcfb_nightmode_ctrl struct, which appears to be handled by the fl driver, on Zelda, at least). And it also doesn't appear to be plugged into anything in the driver code? I do have strace builds around for Zelda/Rex if someone's curious (the one shipped w/ USBNet will prooobably segfault on Zelda/Rex). Last edited by NiLuJe; 03-27-2020 at 01:25 AM.