[Buildroot] [PATCH 2/2] beagle-capes: new package

Frank Hunleth fhunleth at troodon-software.com
Mon Jul 8 13:02:31 UTC 2013


Hi Spenser,

On Sun, Jul 7, 2013 at 11:08 PM, Spenser Gilliland
<spenser at gillilanding.com> wrote:
> Hi Frank,
>
> Your buildroot-bbb repo has been a great reference that helped me get
> this all up and running.
>
>
>> Slightly off topic, but did you run into any issues with the eMMC
>> virtual cape when you did this? The cape manager requests the eMMC
>> cape dtbo before the root file system is mounted. When mdev was
>> finally run from the init scripts, it didn't satisfy that request (I
>> quickly looked through the mdev source, and I didn't see any code to
>> do this. mdev seems to only handle "hotplug" firmware requests). If I
>> manually loaded the eMMC virtual cape dtbo file before the timeout, I
>> could get things to work. I ended up compiling the dtbos into the
>> kernel, but if your br configuration doesn't need to do this, then
>> could you share?
>
> Although, this is not a significant part of my testing (mainly focused
> on hdmi support.) I can say that the emmc is detected very early in
> the boot process and the following is shown during boot.

Cool. I won't be touching HDMI since my cape conflicts with it, so
it's good to know that the HDMI support is being exercised.

>
> [    2.064491] mmc1: BKOPS_EN bit is not set
> [    2.071345] mmc1: new high speed MMC card at address 0001
> [    2.078050] mmcblk1: mmc1:0001 MMC02G 1.78 GiB
> [    2.083224] mmcblk1boot0: mmc1:0001 MMC02G partition 1 1.00 MiB
> [    2.089812] mmcblk1boot1: mmc1:0001 MMC02G partition 2 1.00 MiB
> [    2.098715]  mmcblk1: p1 p2
> [    2.106001]  mmcblk1boot1: unknown partition table
> [    2.113814]  mmcblk1boot0: unknown partition table

It certainly looks like the eMMC is working for you. I'll retest.

> Also, just an fyi to everyone with respect to hdmi output, you must
> have beagle-capes enabled to allow HDMI output as HDMI is implemented
> as a cape. Also, for any capes to work patch [1] is required.
>
> [1] https://github.com/fhunleth/buildroot-bbb/blob/bbb/board/beagleboneblack/linux-0001-Add-missing-DTC-flags.patch

Just as an update on this patch, I've since found out that this
particular patch does exist in Robert Nelson's kernel patch repo.
However, it is specifically not applied to his Debian builds. I'm
checking into this. He also doesn't apply a few other patches. One
notable one is the am335x power management patch since buildroot has
some support for building and loading the power management firmware. I
don't know what the story is there, but the buildroot power management
package can't be used for the bbb at the moment.

>
>> Also, and this is just to understand things better, but if you don't
>> want a firmware file copied to the target, wouldn't you just turn it
>> off in the kernel's configuration?
>
> No, by default Buildroot does not install use the firmware_install
> target.  This is for reasons of disk space usage. The kernel, by
> default, likes to install a lot of firmware.  Additionally, there is a
> linux-firmware package for installing most of this firmware and has
> much more granular control.

Ugh. I didn't realized that. I understand your patch now. Thanks.

>
>> Or were you motivated by the shear volume of dtbo files that you get
>> when you turn on Beaglebone cape support? I was thinking that I wanted
>> finer grain configuration in the Linux kernel so that I could select
>> whether or not I wanted "cape-bone-exptest.dtbo" or
>> "cape-bone-adafruit-lcd", etc., but I don't think that's a br problem.
>> Prior to the Beaglebone capes, I had not seen so many firmware files
>> that I didn't need.
>
> I thought about doing individual capes but the constantly changing
> nature of these capes would require lots of updates and special cases.
> However, the size of dtbo's are negligible so I just installed them
> all.

Sounds good.

>
>> Thanks,
>> Frank
>>
>> p.s. thanks for the opengl work. I have a project coming up in the
>> fall that will need it, so your commits are very timely.
>
> Great to hear.  Hopefully, the Beaglebone Black will be a possible target soon.
>
> Thanks,
> Spenser
>
> --
> Spenser Gilliland
> Computer Engineer
> Doctoral Candidate



--
Frank Hunleth
Troodon Software LLC
http://troodon-software.com/



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