Re: [PATCH 1/3] wifi: ath11k: fix dest ring-buffer corruption

[Johan Hovold <johan@kernel.org>]

On Thu, Jun 05, 2025 at 12:01:29PM +0800, Miaoqing Pan wrote:
> On 6/5/2025 12:24 AM, Jeff Johnson wrote:
> > On 6/3/2025 7:34 PM, Miaoqing Pan wrote:
> >> We previously had extensive discussions on this topic in the
> >> https://lore.kernel.org/linux-wireless/ecfe850c-b263-4bee-b888-c34178e690fc@quicinc.com/
> >> thread. On my platform, dma_rmb() did not work as expected. The issue
> >> only disappeared after disabling PCIe endpoint relaxed ordering in
> >> firmware side. So it seems that HP was updated (Memory write) before
> >> descriptor (Memory write), which led to the problem.
> > 
> > Have all ath11k and ath12k firmware been updated to prevent this problem from
> > the firmware side?
> > 
> No, as this is not a widespread issue, and addressing it would require 
> modifying the core underlying modules of the firmware. Therefore, we 
> chose not to proceed with that approach but instead used the workaround 
> patch I previously submitted.

I strongly suggest you fix this at the firmware level rather than try to
work around it in the kernel to avoid playing whack-a-mole whenever a
new (hard to track down) bug shows up.

The barriers should be enough, but if they are not then the firmware
must be fixed.

Johan