bcm2708-dmaengine: Use more DMA channels (but not 12)

[pelwell]

1. Only the bcm2708_fb drivers uses the legacy DMA API, and
   it requires a BULK-capable channel, so all other types
   (FAST, NORMAL and LITE) can be made available to the regular
   DMA API.

2. DMA channels 11-14 share an interrupt. The driver can't
   handle this, so don't use channels 12-14 (12 was used, probably
   because it appears to have an interrupt, but in reality that
   interrupt is for activity on ANY channel). This may explain
   a lockup encountered when running out of DMA channels.

The combined effect of this patch is to leave 7 DMA channels
available + channel 0 for bcm2708_fb via the legacy API.

See: #1110
#1108

[popcornmix]

Okay - feel free to merge.

[msperl]

Can you also merge it into 4.2?

[pelwell]

It's also on 4.2.

[kukabu]

I'm not sure but look like this commit break sdhost-overlay and spi-dma-overlay
foundation kernel without this pacth (for apt-get) - https://gist.github.com/kukabu/da83930e40d54cb7c454
my custom kernel with this patch - https://gist.github.com/kukabu/f5fc74ea8f0f93481f0e
dmesg diff - https://gist.github.com/kukabu/dd61a4d6f45b343dceab

How do I debug the overlay?

[pelwell]

It's working for me, so one of us is doing something wrong. Can you post your config.txt (just the active bits - you can delete the comments) and the output of:

sudo vcdbg log msg |& grep -viE "(hdmi|gpioman):"

please?

[kukabu]

config.txt - https://gist.github.com/kukabu/9a7f8e508c58618d75b5
vcdbg log msg - https://gist.github.com/kukabu/5629b5c2b4368b0199c5

@pelwell thanks, if it work for you then I something broken :(

[pelwell]

001291.049: Failed to load overlay 'sdhost-overlay'
001295.702: Failed to load overlay 'spi-dma-overlay'

The "-overlay" part is inferred and should not be used - remove it. However, at the moment it still ought to work, so that shouldn't be the problem.

Oh - now I see:

001231.524: Kernel trailer DDTK property says yes

DDTK is an unreleased development feature in the loader that will cause it to look for different filenames. dtoverlay=sdhost will look for sdhost.dtbo instead of sdhost-overlay.dtb, which isn't useful to you at the moment. This mode is selected by a flag in the kernel trailer (added by an unreleased version of mkknlimg).

How have you built this kernel? What does scripts/knlinfo kernel.img show (you may need to change the paths)?

Also, do you really want to turn on both i2c interfaces? i2c0 (or i2c1 on a Rev 1 Model B) is intended for the VideoCore processor. The recommended setting for people using i2c is:

dtparam=i2c_arm=on

which will automatically select the correct interface on each Pi. If you want to explicitly allow the ARM to access the VideoCore I2C then use:

dtparam=i2c_vc=on

but be aware that it will stop the camera from working.

[pelwell]

OK, so that version is released (in the tools repo), but it isn't one found in any of the kernel trees. I suspect you are trying to enable some extra kernel features and ended up setting CONFIG_OF_OVERLAY. This enables the new kernel dynamic Device Tree support, but it isn't very useful because it doesn't include a userspace interface; apart from some self tests, only one driver uses it in the 4.2 tree. Note that this isn't required in a standard Pi kernel because all of the overlay functionality is in the loader.

Your options are:

1. Don't define CONFIG_OF_OVERLAY.
2. Use the version of mkknlimg found in the scripts folder of the kernel tree.

For reference, the latest documentation for kernel building can be found here.

I think any apparent link to this bcm2708-dmaengine commit is just coincidental.

[kukabu]

I found the my mistake. CONFIG_OF_OVERLAY=y in .config.
@pelwell thanks and excuse my disturbing you.