linux-kernel - Re: [PATCH v2] bus: mhi: host: don't free bhie tables during suspend/hibernation

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Message-ID: <7d6b074c-8499-4984-b235-d1285b006ab3@collabora.com>
Date: Mon, 14 Apr 2025 12:32:34 +0500
From: Muhammad Usama Anjum <usama.anjum@...labora.com>
To: Krishna Chaitanya Chundru <quic_krichai@...cinc.com>,
 Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
 Johannes Berg <johannes@...solutions.net>, Jeff Johnson
 <jjohnson@...nel.org>, Jeffrey Hugo <quic_jhugo@...cinc.com>,
 Yan Zhen <yanzhen@...o.com>, Youssef Samir <quic_yabdulra@...cinc.com>,
 Qiang Yu <quic_qianyu@...cinc.com>, Alex Elder <elder@...nel.org>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Kunwu Chan <chentao@...inos.cn>, Jeff Hugo <jeff.hugo@....qualcomm.com>
Cc: kernel@...labora.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
Subject: Re: [PATCH v2] bus: mhi: host: don't free bhie tables during
 suspend/hibernation

On 4/12/25 6:22 AM, Krishna Chaitanya Chundru wrote:
> 
> On 4/12/2025 12:02 AM, Muhammad Usama Anjum wrote:
>> On 4/11/25 1:39 PM, Krishna Chaitanya Chundru wrote:
>>>
>>>
>>> On 4/11/2025 12:32 PM, Muhammad Usama Anjum wrote:
>>>> On 4/11/25 8:37 AM, Krishna Chaitanya Chundru wrote:
>>>>>
>>>>>
>>>>> On 4/10/2025 8:26 PM, Muhammad Usama Anjum wrote:
>>>>>> Fix dma_direct_alloc() failure at resume time during bhie_table
>>>>>> allocation. There is a crash report where at resume time, the memory
>>>>>> from the dma doesn't get allocated and MHI fails to re-initialize.
>>>>>> There may be fragmentation of some kind which fails the allocation
>>>>>> call.
>>>>>>
>>>>>> To fix it, don't free the memory at power down during suspend /
>>>>>> hibernation. Instead, use the same allocated memory again after every
>>>>>> resume / hibernation. This patch has been tested with resume and
>>>>>> hibernation both.
>>>>>>
>>>>>> The rddm is of constant size for a given hardware. While the
>>>>>> fbc_image
>>>>>> size depends on the firmware. If the firmware changes, we'll free and
>>>>> If firmware image will change between suspend and resume ?
>>>> Yes, correct.
>>>>
>>> why the firmware image size will change between suspend & resume?
>>> who will update the firmware image after bootup?
>>> It is not expected behaviour.
>> I was trying to research if the firmware can change or not. I've not
>> found any documentation on it.
>>
>> If the firmare is updated in filesystem before suspend/hibernate, would
>> the new firwmare be loaded the next time kernel resumes as the older
>> firmware is no where to be found?
>>
>> What do you think about this?
>>
> I don't think firmware can be updated before suspend/hibernate. I don't
> see any reason why it can be updated. If you think it can be updated
> please quote relevant doc.
I've not found any documentation on it. Let's wait for others to review
and it it cannot be updated, I'll remove this part.

-- 
Regards,
Usama