Re: [PATCH v2 12/15] ath10k: use new module_firmware_crashed()

On Wed, May 20, 2020 at 8:40 AM Emmanuel Grumbach [off-list ref] wrote:

Since I have been involved quite a bit in the firmware debugging
features in iwlwifi, I think I can give a few insights here.

But before this, we need to understand that there are several sources of issues:
1) the firmware may crash but the bus is still alive, you can still
use the bus to get the crash data
2) the bus is dead, when that happens, the firmware might even be in a
good condition, but since the bus is dead, you stop getting any
information about the firmware, and then, at some point, you get to
the conclusion that the firmware is dead. You can't get the crash data
that resides on the other side of the bus (you may have gathered data
in the DRAM directly, but that's a different thing), and you don't
have much recovery to do besides re-starting the PCI enumeration.

At Intel, we have seen both unfortunately. The bus issues are the ones
that are trickier obviously. Trickier to detect (because you just get
garbage from any request you issue on the bus), and trickier to
handle. One can argue that the kernel should *not* handle those and
let this in userspace hands. I guess it all depends on what component
you ship to your customer and what you customer asks from you  :).

Or the two best approaches:
1) get rid of firmware completely;
2) make it OSS (like SOF).

I think any of these is a right thing to do in long-term perspective.

How many firmwares average computer has? 50? 100? Any of them is a
burden and PITA.

-- 
With Best Regards,
Andy Shevchenko