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

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Message-ID: <8b9eb6f4-6f0c-458d-b1e6-a1893c35b81d@oss.qualcomm.com>
Date: Thu, 3 Jul 2025 09:59:00 +0800
From: Baochen Qiang <baochen.qiang@....qualcomm.com>
To: Muhammad Usama Anjum <usama.anjum@...labora.com>,
        Baochen Qiang <baochen.qiang@....qualcomm.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 7/3/2025 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 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.

> 
> 
>>
>>>  	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.

> 
>  
> 
>