Re: [PATCH 2/3] bus: mhi: don't deinitialize and re-initialize again

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

On 7/3/25 6:59 AM, Baochen Qiang wrote:
> 
> 
> On 7/3/2025 12:12 AM, Muhammad Usama Anjum wrote:
>> Thank you for reviewing.
>>
>> On 7/2/25 8:50 AM, Baochen Qiang wrote:
>>>
>>>
>>> On 6/30/2025 3:43 PM, Muhammad Usama Anjum wrote:
>>>> Don't deinitialize and reinitialize the HAL helpers. The dma memory is
>>>> deallocated and there is high possibility that we'll not be able to get
>>>> the same memory allocated from dma when there is high memory pressure.
>>>>
>>>> Tested-on: WCN6855 WLAN.HSP.1.1-03926.13-QCAHSPSWPL_V2_SILICONZ_CE-2.52297.6
>>>>
>>>> Fixes: d5c65159f289 ("ath11k: driver for Qualcomm IEEE 802.11ax devices")
>>>> Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
>>>> ---
>>>>  drivers/net/wireless/ath/ath11k/core.c | 5 -----
>>>>  1 file changed, 5 deletions(-)
>>>>
>>>> diff --git a/drivers/net/wireless/ath/ath11k/core.c b/drivers/net/wireless/ath/ath11k/core.c
>>>> index 4488e4cdc5e9e..bc4930fe6a367 100644
>>>> --- a/drivers/net/wireless/ath/ath11k/core.c
>>>> +++ b/drivers/net/wireless/ath/ath11k/core.c
>>>> @@ -2213,14 +2213,9 @@ static int ath11k_core_reconfigure_on_crash(struct ath11k_base *ab)
>>>>  	mutex_unlock(&ab->core_lock);
>>>>  
>>>>  	ath11k_dp_free(ab);
>>>> -	ath11k_hal_srng_deinit(ab);
>>>>  
>>>>  	ab->free_vdev_map = (1LL << (ab->num_radios * TARGET_NUM_VDEVS(ab))) - 1;
>>>>  
>>>> -	ret = ath11k_hal_srng_init(ab);
>>>> -	if (ret)
>>>> -		return ret;
>>>> -
>>>
>>> while I agree there is no need of a dealloc/realloc, we can not simply remove calling the
>>> _deinit()/_init() pair. At least the memset() cleanup to hal parameters (e.g.
>> Why do is it being done in the resume handler? Shouldn't those parameters be cleaned up
>> in resume handler? So when device wakes up, its state is already correct.
>>
> 
> Hmm... not quite understand your question. Can you elaborate?

I'm trying to understand the possibility of cleanup of hal in suspend handler. For example:
* The driver has been loaded and has been working fine.
* The user called suspend. So all devices would be suspended.
* In suspend handler of the ath11k, we should do the necessary cleanups of the states
  like hal.
* When the device would resume after long time, the hal would have the correct state
  already. So we'll not need to deinit and init again.

> 
>> I'm not sure why it worked every time when I tested it on my device.
>>
>>> avail_blk_resource, current_blk_index and num_shadow_reg_configured etc.) inside the
>>> _init() needs to be kept as the later operation needs a clean state of them.
>> So should we just memset these 3?
> 
> more than them I think. We need to take care of all entries in hal since current code is
> memset them all.
I see. So memset the whole ath11k hal structure other than the config.

> 
>>
>>
>>>
>>>>  	clear_bit(ATH11K_FLAG_CRASH_FLUSH, &ab->dev_flags);
>>>>  
>>>>  	ret = ath11k_core_qmi_firmware_ready(ab);
>>>
>>> the _deinit() is still getting called in case ath11k_core_qmi_firmware_ready() fails,
>>> making it a little odd since there is no _init() anymore with this change, though this is
>>> the way of current logic (I mean the hal is currently deinit in the error path).
>>>
>>> Thinking it more, if we hit the error path, seems the only way is to remove ath11k module.
>>> In that case the _deinit() would be called again in ath11k_pci_remove(), leading to issues
>>> (at least I see a double free of hal->srng_config). But this is another topic which can be
>>> fixed in a separate patch.
>>
>> I don't think this is the problem as HAL is already initialized when before the system has
>> suspended. So by removing deinit() and init() pairs, the HAL still remains initialized. Or
>> maybe I've missed something?
> 
> Yeah, it is OK in normal path. However in error path we face issues.
For example:
* When driver was initialized the first time, the hal was init.
* Then system was suspended and hal doesn't get deinit.
* At system resume, the hal is already init. We can memset some status variables. But its
  initialized already from the first time. (considering this patch that deinit/init have
  been removed)
* So at this stage if some error occurs and we can call the deinit in the error paths.