Re: [PATCH v4] wifi: ath11k: Fix MHI target memory reuse logic

[Muhammad Usama Anjum <usama.anjum@collabora.com>]

On 4/28/25 7:03 AM, Baochen Qiang wrote:
> 
> 
> On 4/25/2025 7:08 PM, Baochen Qiang wrote:
>>
>>
>> On 4/25/2025 7:04 PM, Muhammad Usama Anjum wrote:
>>> Firmware requests 2 segments at first. The first segment is of 6799360
>>> whose allocation fails due to dma remapping not available. The success
>>> is returned to firmware. Then firmware asks for 22 smaller segments
>>> instead of 2 big ones. Those get allocated successfully. At suspend/
>>> hibernation time, these segments aren't freed as they will be reused
>>> by firmware after resuming.
>>>
>>> After resuming, the firmware asks for the 2 segments again with the
>>> first segment of 6799360 size. Since chunk->vaddr is not NULL, the
>>> type and size are compared with the previous type and size to know if
>>> it can be reused or not. Unfortunately, it is detected that it cannot
>>> be reused and this first smaller segment is freed. Then we continue to
>>> allocate 6799360 size memory which fails and ath11k_qmi_free_target_mem_chunk()
>>> is called which frees the second smaller segment as well. Later success
>>> is returned to firmware which asks for 22 smaller segments again. But
>>> as we had freed 2 segments already, we'll allocate the first 2 new
>>> smaller segments again and reuse the remaining 20. Hence 20 small
>>> segments are being reused instead of 22.
>>>
>>> Add skip logic when vaddr is set, but size/type don't match. Use the
>>> same skip and success logic as used when dma_alloc_coherent() fails.
>>> By skipping, the possibility of resume failure due to kernel failing to
>>> allocate memory for QMI can be avoided.
>>>
>>> 	kernel: ath11k_pci 0000:03:00.0: failed to allocate dma memory for qmi (524288 B type 1)
>>> 	ath11k_pci 0000:03:00.0: failed to allocate qmi target memory: -22
>>>
>>> Tested-on: WCN6855 WLAN.HSP.1.1-03926.13-QCAHSPSWPL_V2_SILICONZ_CE-2.52297.6
>>>
>>> Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
>>> ---
>>> Changes since v1:
>>> - Update description
>>>
>>> Changes since v2:
>>> - Update description
>>>
>>> Changes since v3:
>>> - Update description
> 
> The subject since previous is changed, but not mentioned here.
> 
> Please describe all your changes.
> 
>>> ---
>>>  drivers/net/wireless/ath/ath11k/qmi.c | 9 +++++++++
>>>  1 file changed, 9 insertions(+)
>>>
>>> diff --git a/drivers/net/wireless/ath/ath11k/qmi.c b/drivers/net/wireless/ath/ath11k/qmi.c
>>> index 47b9d4126d3a9..2782f4723e413 100644
>>> --- a/drivers/net/wireless/ath/ath11k/qmi.c
>>> +++ b/drivers/net/wireless/ath/ath11k/qmi.c
>>> @@ -1993,6 +1993,15 @@ static int ath11k_qmi_alloc_target_mem_chunk(struct ath11k_base *ab)
>>>  			    chunk->prev_size == chunk->size)
>>>  				continue;
>>>  
>>> +			if (ab->qmi.mem_seg_count <= ATH11K_QMI_FW_MEM_REQ_SEGMENT_CNT) {
>>> +				ath11k_dbg(ab, ATH11K_DBG_QMI,
>>> +					   "size/type mismatch (current %d %u) (prev %d %u), try later with small size\n",
>>> +					    chunk->size, chunk->type,
>>> +					    chunk->prev_size, chunk->prev_type);
>>> +				ab->qmi.target_mem_delayed = true;
>>> +				return 0;
>>> +			}
>>> +
>>>  			/* cannot reuse the existing chunk */
>>>  			dma_free_coherent(ab->dev, chunk->prev_size,
>>>  					  chunk->vaddr, chunk->paddr);
>>
>> LGTM
>>
>> Reviewed-by: Baochen Qiang <quic_bqiang@quicinc.com>
> 
> Withdraw above tag as I didn't notice that the patch subject is incorrect since v3.
> 
> The QMI memory has nothing to do with MHI. IMO the v1/v2 subject is good:
> 
> 	wifi: ath11k: Fix memory reuse logic
> 
> while even better mention QMI:
> 
> 	wifi: ath11k: Fix QMI memory reuse logicJeff had asked for changed subject here [1]. Let me change again and
send the patch.

[1]
https://lore.kernel.org/all/228546c4-a4b5-4f21-950d-2623a48f60a6@oss.qualcomm.com

> 
> 
>>
> 


-- 
Regards,
Usama