Message-ID: <7b8ea9ba-02ef-4676-a4d3-d088920283c3@oss.qualcomm.com>
Date: Mon, 7 Jul 2025 17:00:11 +0800
From: Baochen Qiang <baochen.qiang@....qualcomm.com>
To: Muhammad Usama Anjum <usama.anjum@...labora.com>,
        Manivannan Sadhasivam <mani@...nel.org>,
        Jeff Johnson <jjohnson@...nel.org>,
        Jeff Hugo <jeff.hugo@....qualcomm.com>,
        Youssef Samir <quic_yabdulra@...cinc.com>,
        Matthew Leung <quic_mattleun@...cinc.com>, Yan Zhen <yanzhen@...o.com>,
        Alexander Wilhelm <alexander.wilhelm@...termo.com>,
        Alex Elder <elder@...nel.org>, Kunwu Chan <chentao@...inos.cn>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Siddartha Mohanadoss <smohanad@...eaurora.org>,
        Sujeev Dias <sdias@...eaurora.org>,
        Julia Lawall <julia.lawall@...6.fr>, John Crispin <john@...ozen.org>,
        Muna Sinada <quic_msinada@...cinc.com>,
        Venkateswara Naralasetty <quic_vnaralas@...cinc.com>,
        Maharaja Kennadyrajan <quic_mkenna@...cinc.com>, mhi@...ts.linux.dev,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-wireless@...r.kernel.org, ath11k@...ts.infradead.org
Cc: kernel@...labora.com
Subject: Re: [PATCH 2/3] bus: mhi: don't deinitialize and re-initialize again



On 7/7/2025 4:19 PM, Muhammad Usama Anjum wrote:
> 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@...labora.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.

The hal cleanup is not only needed by suspend/resume, but also a step of reset/recover
process. So If we are moving the cleanup to suspend handler, similar stuff needs to be
done for reset/recover as well.

> 
>>
>>> 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.
> 
> 

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