Re: wifi: ath12k: start-up crash with WCN7850 hw2.0 on TI AM69-SK board

[Francesco Dolcini <francesco@dolcini.it>]

Hello,

On Tue, May 06, 2025 at 01:56:11PM +0800, Baochen Qiang wrote:
> On 4/30/2025 8:50 PM, Parth Panchoil wrote:
> > On Wed, 2025-02-19 at 18:18 +0800, Baochen Qiang wrote:
> >> On 2/5/2025 10:20 AM, Baochen Qiang wrote:
> >>> On 1/27/2025 10:01 PM, Parth Panchoil wrote:
> >>>> I am currently debugging the ath12k_pci_enable_ltssm start up
> >>>> crash/bug
> >>>> with the mainline kernel on my system and would like to share my
> >>>> observations so far:
> >>>>
> >>>> The ath12k mainline driver gets stuck at this specific line: 
> >>>> https://github.com/torvalds/linux/blob/9c5968db9e625019a0ee5226c7eebef5519d366a/drivers/net/wireless/ath/ath12k/pci.c#L295
> >>>> in the ath12k_pci_enable_ltssm  which attempts to read
> >>>> GCC_GCC_PCIE_HOT_RST, particularly
> >>>> https://github.com/torvalds/linux/blob/9c5968db9e625019a0ee5226c7eebef5519d366a/drivers/net/wireless/ath/ath12k/pci.c#L1209

...

> >>
> >> -#define GCC_GCC_PCIE_HOT_RST                   0x1e38338
> >> +#define GCC_GCC_PCIE_HOT_RST                   0x1e40304

...

> 
> GCC_GCC_PCIE_HOT_RST is wrongly defined, normally this should not cause any critical
> issue, because IMO the RC is expected to return 0xffffffff when accessing a non-exist
> register. However in your case kernel crashes, so seems RC does not behave well, maybe not
> following spec?
> 
> anyway I will submit a patch to fix it.

Any update on this? I can easily submit a patch myself, just let me
know. Because of this bug we have a crash that is preventing us to use
the device.

Francesco