Unable to initialise DMA channels. Falling back to PIO

[adolchristin]

I'm running archlinux arm on my raspberry pi 2 and I'm seeing the following during boot:

mmc-bcm2835 3f300000.mmc: mmc-bcm2835: Unable to initialise DMA channels. Falling back to PIO

I added bcm2708.bcm2835_mmc=1 to my /boot/cmdline.txt but I'm still seeing the same thing. In any case I was pretty sure this new driver was the default. Is the archlinux kernel compiled with CONFIG_DMA_BCM2708=y ?

[moonman]

https://github.com/archlinuxarm/PKGBUIL ... g.v7#L3626

[adolchristin]

Thanks for the link. Looks like appropriate values are set, any idea why I'm falling back to programmed IO? Is this expected behaviour and I just shouldn't worry about it?

[towolf]

I’m having the same issue. PIO mode is not good.

[adolchristin]

It's especially bad for writing it seems like. I'm going to try the linux-armv7-rc kernel to see if there's any difference when I get home. Unfortunately I only recently got my rpi so I can't say if this worked before.

[towolf]

It worked before. I’m not sure when it started, during the most recent kernel update or the one before.

[adolchristin]

After further reading I'm wondering if it's a mismatch between the compiled kernel and the device tree blob? I'm fairly new to the RPI so deciphering all the broadcom specific stuff is a little tricky.

[trolly]

Same problem here. It showed up after doing these updates:

$this->bbcode_second_pass_code('', '[2015-05-20 19:27] [PACMAN] Running 'pacman -Syu'
[2015-05-20 19:27] [PACMAN] synchronizing package lists
[2015-05-20 19:27] [PACMAN] starting full system upgrade
[2015-05-20 19:27] [ALPM] transaction started
[2015-05-20 19:27] [ALPM] upgraded dhcpcd (6.8.2-1 -> 6.9.0-1)
[2015-05-20 19:27] [ALPM] upgraded libssh (0.6.5-1 -> 0.7.0-1)
[2015-05-20 19:27] [ALPM] upgraded ffmpeg (1:2.6.2-1 -> 1:2.6.3-1)
[2015-05-20 19:27] [ALPM] upgraded iproute2 (3.19.0-1 -> 4.0.0-1)
[2015-05-20 19:27] [ALPM] upgraded linux-raspberrypi (3.18.13-1 -> 3.18.13-2)
[2015-05-20 19:28] [ALPM-SCRIPTLET] >>> Updating module dependencies. Please wait ...
[2015-05-20 19:28] [ALPM] upgraded mdadm (3.3.2-1 -> 3.3.2-2)
[2015-05-20 19:28] [ALPM] upgraded raspberrypi-firmware-bootloader (20150513-1 -> 20150518-1)
[2015-05-20 19:28] [ALPM] upgraded raspberrypi-firmware-bootloader-x (20150513-1 -> 20150518-1)
[2015-05-20 19:28] [ALPM] upgraded raspberrypi-firmware-tools (20150513-1 -> 20150518-1)
[2015-05-20 19:28] [ALPM] upgraded raspberrypi-firmware-examples (20150513-1 -> 20150518-1)
[2015-05-20 19:28] [ALPM] upgraded raspberrypi-firmware (20150513-1 -> 20150518-1)
[2015-05-20 19:28] [ALPM] transaction completed
')

[adolchristin]

Thanks for the info, I'm learning more about this raspberry pi stuff. Apparently the broadcom stuff is provided in the firmware packages as binary blobs which the kernel interacts with. I'm starting to think that there's a mismatch between the kernel and the binary blob but it's pretty hard to diagnose what's happening in the blobs since, well, they're binary

[Evils]

Same problem here since I updated yesterday... a fix would be nice or at least a fallback

Edit:
After downgrading one package after another, it seems to be in here:

$this->bbcode_second_pass_quote('', '
')[2015-05-20 19:27] [ALPM] upgraded linux-raspberrypi (3.18.13-1 -> 3.18.13-2)