@ainu
Perhaps the problem is not the preset - the future will show.
240 MHz works fine on 650D/700D/6D, I have been using it for a year, never switched to 48 MHz mode using Sandisk Extreme PRO UHS-I U3 170 MB/s cards, never had data corruption with it.
-My my expectations are:
1. Canon has a function which traces card controllers speed clocks/or something makes Canon think something isn't usual is happening regarding how card is being configured which doesn't match what Canon code is expecting --> Switches to safe mode (48 MHz).
We already know there is something like that, but this was a different case:
https://www.magiclantern.fm/forum/index.php?topic=12862.msg228485#msg228485https://www.magiclantern.fm/forum/index.php?topic=12862.msg228510#msg228510I don't think it's related to 70D issue, what was happening there is my *Sandisk Extreme PRO UHS-I U3
95 MB/s was giving up (because the card had 99 MB/s write speed with 240 MHz overclock, probably it couldn't handle this really high write speed) or **SD card reader in camera was overheating/signal isn't clean. (My Sandisk Extreme PRO UHS-I U3
170 MB/s cards have fixed write speed of ~90 MB/s, which is probably made the signal cleaner/normal).
*Also my Sandisk Extreme PRO UHS-I U3
95 MB/s have 45 MB/s read/write speed using the card reader on PC, while the
170 MB/s version was giving ~85 MB/s write speed with same
card reader, newer cards from Sandisk is more fine tuned I guess.
**I put the camera in fridge with 95 MB/s Sandisk inside the camera (240 MHz) as @names_are_hard said it might be overheating issue, and made some tests, the card never switched to 48 MHz mode but it had speed drops, and a recording was stopping suddenly.
2. A setting needs to be changed on EOS M/70D/5D3 to accept these high clocks speeds, little experiment on 700D:
-I called sdSoftReset (which switches the card to 48 MHz mode), write speed becomes 21 MB/s (from ~40 MB/s)
-I changed registers values to 96 MHz preset (96 MHz preset is the default preset on 700D and all other DIGIC 5 cameras except for 5D3), write speed became 36 MB/s which a little lower than default 96 MHz mode
-It turned out AccessMode was changed from 7 (default) to 3 (after sdSoftReset), I re-patched AccessMode to 7 and got ~40 MB/s write speed which is the correct one
-So now we are in default 96 MHz mode after a sdSoftReset, let's overclock the values again to 160MHz/192MHz/240 MHz --> Card full; card can't be accessed (another safe mode but safer from Canon)
-That's why I believe there is a setting we are missing, finding it out might solve the problem for 5D3 and probably for EOS M/70D
3. Third expectation: it might just the wrong 240 MHz values
