Qualcomm proprietary binary files / flashall / qdl / EDL

I have a question about those binaries provided in Recovery package, such as cmnlib.mbn, emmc_appsboot.mbn, gpt_main0.bin, patch.xml, etc.
I understand those are proprietary and needed for some low level things, but I am not clear about how they affect the system configuration.

We use one of the D820 SOMs. We were struggling to re-configure a BLSP, then the SOM vendor provided us a different set of binaries, and then it worked.

This was a surprise, because my understanding was, BLSP could be configured by Device Tree and/or kernel patch, but it doesn’t look like that way.
I am still puzzled, but does this sound correct? To re-configure BLSP, you need to change something in those binaries in addition to DT/kernel change.

Sorry for an obscure question and thanks,

It’s not as simple as you might think. It’s those low level things that were blocking access to the BLSP you wanted to use.

Inside the 820 there are many processors and subsystems. During the early boot phases access to specific peripherals are assigned to specific processors or subsystems. All of this is done by the proprietary binaries before LK starts, and long before the device tree has been read.

This is done as part of the security of the subsystems. For example the audio DSP would usually be assigned exclusive access to the I2S ports, however I2S access could be assigned to both the Audio DSP and the main CPUs, but then the user would have to ensure that there was no contention in the usage of the I2S hardware.

It looks like the BLSP you were trying to access had been assigned to a sub-system other than the main CPU cores, hence you couldn’t access it. I am not sure what happened in this specific case, but either newer proprietary binaries allowed access to the BLSP in question, or the SOM vendor was able to build a custom version of the proprietary binaries which assigned access to the BLSP to the main CPUs.

Once the main CPUs have physical access to the BLSP registers, then you still need to set up the device tree correctly.

Still looking for work…

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Thank you so much. It makes perfect sense.