Re: [PATCH RESEND] wifi: ath12k: fix channel list copy on big endian

On Thu, Jul 02, 2026 at 10:44:46AM +0200, Alexander Wilhelm wrote:
> On Thu, Jul 02, 2026 at 04:27:44PM +0800, Baochen Qiang wrote:
> > 
> > 
> > On 6/29/2026 3:46 PM, Alexander Wilhelm wrote:
> > > The ath12k_wmi_scan_req_arg structure defines the channel list in
> > > CPU-native order, while wmi_start_scan_cmd expects the values in
> > > little-endian format. The simple memcpy causes the hardware scan to fail on
> > > big-endian architectures. Set __le32* type for the tmp_ptr and swap channel
> > > values to support both architectures correctly.
> > > 
> > > Signed-off-by: Alexander Wilhelm <[email protected]>
> > > ---
> > >  drivers/net/wireless/ath/ath12k/wmi.c | 8 +++++---
> > >  1 file changed, 5 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/drivers/net/wireless/ath/ath12k/wmi.c b/drivers/net/wireless/ath/ath12k/wmi.c
> > > index 65a05a9520ff..9e1d3c662852 100644
> > > --- a/drivers/net/wireless/ath/ath12k/wmi.c
> > > +++ b/drivers/net/wireless/ath/ath12k/wmi.c
> > > @@ -2571,7 +2571,8 @@ int ath12k_wmi_send_scan_start_cmd(struct ath12k *ar,
> > >  	struct wmi_tlv *tlv;
> > >  	void *ptr;
> > >  	int i, ret, len;
> > > -	u32 *tmp_ptr, extraie_len_with_pad = 0;
> > > +	__le32 *tmp_ptr;
> > > +	u32 extraie_len_with_pad = 0;
> > >  	struct ath12k_wmi_hint_short_ssid_arg *s_ssid = NULL;
> > >  	struct ath12k_wmi_hint_bssid_arg *hint_bssid = NULL;
> > >  
> > > @@ -2656,9 +2657,10 @@ int ath12k_wmi_send_scan_start_cmd(struct ath12k *ar,
> > >  	tlv = ptr;
> > >  	tlv->header = ath12k_wmi_tlv_hdr(WMI_TAG_ARRAY_UINT32, len);
> > >  	ptr += TLV_HDR_SIZE;
> > > -	tmp_ptr = (u32 *)ptr;
> > > +	tmp_ptr = (__le32 *)ptr;
> > >  
> > > -	memcpy(tmp_ptr, arg->chan_list, arg->num_chan * 4);
> > > +	for (i = 0; i < arg->num_chan; i++)
> > > +		tmp_ptr[i] = cpu_to_le32(arg->chan_list[i]);
> > >  
> > >  	ptr += len;
> > >  
> > > 
> > 
> > seems hint_s_ssid and hint_bssid at the last also need the endian conversion?

`hist_s_ssid` and `hint_bssid` are both structs within
`ath12k_wmi_scan_req_arg`, and the remaining member variables are also stored in
CPU order. Therefore, it seems wrong to me to perform byte swapping at this
point. What I actually need to swap is the data written through `ptr`, not the
structure members themselves. For that reason, I could also use the `__le32
*tmp_ptr` approach. What do you think about that?

One thing I am still unsure about is the use of `ether_addr_copy()`. Can I
simply copy the bytes as-is here, or does the address also need to be
byte-swapped? I could not find any place where this address is being populated,
so I am not sure what byte order it is expected to be in.


Best regards
Alexander Wilhelm