linux-kernel - Re: ath12k: REO status on PPC does not work

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Message-ID: <573c76a8-c2a0-4b9c-b5a8-762b8d094b81@dd-wrt.com>
Date: Fri, 15 Aug 2025 11:55:14 +0200
From: Sebastian Gottschall <s.gottschall@...wrt.com>
To: Alexander Wilhelm <alexander.wilhelm@...termo.com>,
 Jeff Johnson <jjohnson@...nel.org>
Cc: ath12k@...ts.infradead.org, linux-wireless@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: ath12k: REO status on PPC does not work

i played already with big endian platforms and ath11k (not ath12k) for 
months. there is also a problem with the dma descriptors. the firmware 
simply doesnt support big endian with host communication at the end even 
if there is a endian flag for the firmware.  dont get into this rabit 
hole. (i worked 3 months on it and gave up)
at the end (i was working on a cavium octeon platform at that time) i 
just switched the kernel boot to little endian which is possible on many 
ppc platforms too.

Am 15.08.2025 um 10:13 schrieb Alexander Wilhelm:
> Hello devs,
>
> I'm currently working on getting the 'ath12k' driver running on a big endian
> PowerPC platform and have encountered the following issue.
>
> In the function 'ath12k_dp_rx_process_reo_status', the REO status is determined
> by inspecting memory that the hardware has previously written via DMA.
> Specifically, during the call to 'ath12k_hal_srng_access_begin', the driver
> reads the value of 'hp_addr' for the destination ring (in my case, always with
> ID 21). On the big endian platform, this value is consistently 0, which prevents
> the REO status from being updated.
>
> Interestingly, DMA read/write accesses work fine for other rings, just not for
> this one. What makes the REO status ring so special? I couldn’t find anything in
> the initialization routine that would explain the difference.
>
> Could anyone give me a hint on what I should be looking for?
>
>
> Best regards
> Alexander Wilhelm
>
>