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

[Jeff Hugo <jeff.hugo@oss.qualcomm.com>]

On 4/18/2025 2:10 AM, Muhammad Usama Anjum wrote:
> On 4/14/25 7:14 PM, Jeff Hugo wrote:
>> On 4/14/2025 1:32 AM, Muhammad Usama Anjum wrote:
>>> 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.
>>>
>>
>> Wouldn't this be trivial to test?  Boot the device, go modify the
>> firmware on the filesystem, then go through a suspend cycle.
> I just tested this. I've used an old firmware from last year vs the
> latest one.
> 
> Firmware A: old firmware size: 5349376
> Firmware B: new firmware size: 5165056
> 
> A here has bigger size.
> 
> 1. I loaded A at boot and then replaced the firmwares in filesystem with
> B before syspend. At resume time, B was loaded fine by freeing the
> bigger memory area and allocating the smaller one.
> 
> 2. I loaded B and then replaced A in its place before suspend. At resume
> time, memory was freed and larger memory was allocated. But driver
> wasn't able to initialize correctly:
> 
> [  184.051902] ath11k_pci 0000:03:00.0: timeout while waiting for
> restart complete
> [  184.051916] ath11k_pci 0000:03:00.0: failed to resume core: -110
> [  184.051923] ath11k_pci 0000:03:00.0: PM: dpm_run_callback():
> pci_pm_resume returns -110
> [  184.051945] ath11k_pci 0000:03:00.0: PM: failed to resume async:
> error -110
> [  187.251911] ath11k_pci 0000:03:00.0: wmi command 16387 timeout
> [  187.251924] ath11k_pci 0000:03:00.0: failed to send
> WMI_PDEV_SET_PARAM cmd
> [  187.251933] ath11k_pci 0000:03:00.0: failed to enable dynamic bw: -11
> 
> So should we generalize above that changing firmware at
> suspend/hibernation time isn't supported. If firmware package is
> updated, does user restarts every time?

You may want to review how other devices handle this.  I can think of 
these threads as potential reference

https://lore.kernel.org/all/CAPM=9twyvq3EWkwUeoTdMMj76u_sRPmUDHWrzbzEZFQ8eL++BQ@mail.gmail.com/
https://lore.kernel.org/all/20250207012531.621369-1-airlied@gmail.com/

-Jeff