lucascastro: just guessing: do you have the right dtb?
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Hey, is.there any way to get displays driven with our 2d/3d stack other then the available rgb/tcon? I.e. can ibdrive an SPI diaplay for example?
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how many fps can you get with an SPI display?
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wens: depends on the resolution. Usually not more than a vga.
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yeah, it's slow
good for low-refresh info display, photo frames etc
not good for anything >10-15fps
wens: the limit is the spi controller in the lcd display. For example, i am using a display with a ILI9488. Specifies a maximum spi clock cycle of 50ns. (Thats 20Mhz)
wens: its a 480x320 display and needs 24 bits of data per pixel in spi mode.
wens: so 20,000,000 / 24 / 480 / 320 = Maximum frame rate (according to specs) = 5.4 frames per second.
wens: however, many people have success running with higher clocks than specified, but even if you can double it, you will only get < 11 frames per second.
You can do the same calculations for any spi panel.
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the SPI in the socs from sunxi can run up to 100Mhz (i believe) so in theory that panel could do 27 frames per second, but the controller on the lcd can't handle it. The limit with these displays is always the lcd controller, when using a soc like the allwinner ones, or the raspberry pi.
oliv3r: in theory if you use fbtft or tinydrm you should be able to use a spi lcd like a normal screen (just with a low refresh rate)
i was running linux console via fbtft on 128x64
works, but not much screen estate ;)
KotCzarny: yes, but for a status screen, or a specific application could be plenty. but console, yeah not very useful.
i have a plan for a spi tft that can run with a spi clock up to 150mhz using a tiny fpga to do serial to parallel conversion.
why not just use some proper display connector?
KotCzarny: not always available.
especially for small size screens (sub 4")
spi2mipi dbi type B :)
the logic is very very simple and the fpga is very cheap ($2)