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Date: Thu, 29 Feb 2024 18:33:43 +0800
From: Baochen Qiang <quic_bqiang@...cinc.com>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
"Kalle Valo
(QUIC)" <quic_kvalo@...cinc.com>
CC: <ath11k@...ts.infradead.org>, <linux-wireless@...r.kernel.org>,
<linux-arm-msm@...r.kernel.org>, <mhi@...ts.linux.dev>,
<davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
<pabeni@...hat.com>, <netdev@...r.kernel.org>
Subject: Re: [PATCH v4 1/3] bus: mhi: host: add mhi_power_down_keep_dev()
On 2/29/2024 6:12 PM, Manivannan Sadhasivam wrote:
> On Wed, Feb 28, 2024 at 10:22:41AM +0800, Baochen Qiang wrote:
>> ath11k fails to resume:
>>
>> ath11k_pci 0000:06:00.0: timeout while waiting for restart complete
>>
>> This happens because when calling mhi_sync_power_up() the MHI subsystem
>> eventually calls device_add() from mhi_create_devices() but the device
>> creation is deferred:
>>
>> mhi mhi0_IPCR: Driver qcom_mhi_qrtr force probe deferral
>>
>> The reason for deferring device creation is explained in dpm_prepare():
>>
>> /*
>> * It is unsafe if probing of devices will happen during suspend or
>> * hibernation and system behavior will be unpredictable in this case.
>> * So, let's prohibit device's probing here and defer their probes
>> * instead. The normal behavior will be restored in dpm_complete().
>> */
>>
>> Because the device probe is deferred, the qcom_mhi_qrtr_probe() is not
>> called and thus MHI channels are not prepared:
>>
>> So what this means that QRTR is not delivering messages and the QMI connection
>> is not working between ath11k and the firmware, resulting a failure in firmware
>> initialization.
>>
>> To fix this add new function mhi_power_down_keep_dev() which doesn't destroy
>> the devices for channels during power down. This way we avoid probe defer issue
>> and finally can get ath11k hibernation working with the following patches.
>>
>> Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.30
>>
>> Signed-off-by: Kalle Valo <quic_kvalo@...cinc.com>
>
> Did Kalle co-author this patch? If so, his Co-developed-by tag should be
> added.
Hmm, I'm not sure... I would like Kalle's thoughts on this.
>
>> Signed-off-by: Baochen Qiang <quic_bqiang@...cinc.com>
>
> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
>
> - Mani
>
>> ---
>> drivers/bus/mhi/host/internal.h | 4 +++-
>> drivers/bus/mhi/host/pm.c | 42 ++++++++++++++++++++++++++++-----
>> include/linux/mhi.h | 18 +++++++++++++-
>> 3 files changed, 56 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/bus/mhi/host/internal.h b/drivers/bus/mhi/host/internal.h
>> index 5fe49311b8eb..aaad40a07f69 100644
>> --- a/drivers/bus/mhi/host/internal.h
>> +++ b/drivers/bus/mhi/host/internal.h
>> @@ -80,6 +80,7 @@ enum dev_st_transition {
>> DEV_ST_TRANSITION_FP,
>> DEV_ST_TRANSITION_SYS_ERR,
>> DEV_ST_TRANSITION_DISABLE,
>> + DEV_ST_TRANSITION_DISABLE_DESTROY_DEVICE,
>> DEV_ST_TRANSITION_MAX,
>> };
>>
>> @@ -90,7 +91,8 @@ enum dev_st_transition {
>> dev_st_trans(MISSION_MODE, "MISSION MODE") \
>> dev_st_trans(FP, "FLASH PROGRAMMER") \
>> dev_st_trans(SYS_ERR, "SYS ERROR") \
>> - dev_st_trans_end(DISABLE, "DISABLE")
>> + dev_st_trans(DISABLE, "DISABLE") \
>> + dev_st_trans_end(DISABLE_DESTROY_DEVICE, "DISABLE (DESTROY DEVICE)")
>>
>> extern const char * const dev_state_tran_str[DEV_ST_TRANSITION_MAX];
>> #define TO_DEV_STATE_TRANS_STR(state) (((state) >= DEV_ST_TRANSITION_MAX) ? \
>> diff --git a/drivers/bus/mhi/host/pm.c b/drivers/bus/mhi/host/pm.c
>> index 8b40d3f01acc..11c0e751f223 100644
>> --- a/drivers/bus/mhi/host/pm.c
>> +++ b/drivers/bus/mhi/host/pm.c
>> @@ -468,7 +468,8 @@ static int mhi_pm_mission_mode_transition(struct mhi_controller *mhi_cntrl)
>> }
>>
>> /* Handle shutdown transitions */
>> -static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl)
>> +static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl,
>> + bool destroy_device)
>> {
>> enum mhi_pm_state cur_state;
>> struct mhi_event *mhi_event;
>> @@ -530,8 +531,16 @@ static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl)
>> dev_dbg(dev, "Waiting for all pending threads to complete\n");
>> wake_up_all(&mhi_cntrl->state_event);
>>
>> - dev_dbg(dev, "Reset all active channels and remove MHI devices\n");
>> - device_for_each_child(&mhi_cntrl->mhi_dev->dev, NULL, mhi_destroy_device);
>> + /*
>> + * Only destroy the 'struct device' for channels if indicated by the
>> + * 'destroy_device' flag. Because, during system suspend or hibernation
>> + * state, there is no need to destroy the 'struct device' as the endpoint
>> + * device would still be physically attached to the machine.
>> + */
>> + if (destroy_device) {
>> + dev_dbg(dev, "Reset all active channels and remove MHI devices\n");
>> + device_for_each_child(&mhi_cntrl->mhi_dev->dev, NULL, mhi_destroy_device);
>> + }
>>
>> mutex_lock(&mhi_cntrl->pm_mutex);
>>
>> @@ -821,7 +830,10 @@ void mhi_pm_st_worker(struct work_struct *work)
>> mhi_pm_sys_error_transition(mhi_cntrl);
>> break;
>> case DEV_ST_TRANSITION_DISABLE:
>> - mhi_pm_disable_transition(mhi_cntrl);
>> + mhi_pm_disable_transition(mhi_cntrl, false);
>> + break;
>> + case DEV_ST_TRANSITION_DISABLE_DESTROY_DEVICE:
>> + mhi_pm_disable_transition(mhi_cntrl, true);
>> break;
>> default:
>> break;
>> @@ -1175,7 +1187,8 @@ int mhi_async_power_up(struct mhi_controller *mhi_cntrl)
>> }
>> EXPORT_SYMBOL_GPL(mhi_async_power_up);
>>
>> -void mhi_power_down(struct mhi_controller *mhi_cntrl, bool graceful)
>> +static void __mhi_power_down(struct mhi_controller *mhi_cntrl, bool graceful,
>> + bool destroy_device)
>> {
>> enum mhi_pm_state cur_state, transition_state;
>> struct device *dev = &mhi_cntrl->mhi_dev->dev;
>> @@ -1211,15 +1224,32 @@ void mhi_power_down(struct mhi_controller *mhi_cntrl, bool graceful)
>> write_unlock_irq(&mhi_cntrl->pm_lock);
>> mutex_unlock(&mhi_cntrl->pm_mutex);
>>
>> - mhi_queue_state_transition(mhi_cntrl, DEV_ST_TRANSITION_DISABLE);
>> + if (destroy_device)
>> + mhi_queue_state_transition(mhi_cntrl,
>> + DEV_ST_TRANSITION_DISABLE_DESTROY_DEVICE);
>> + else
>> + mhi_queue_state_transition(mhi_cntrl,
>> + DEV_ST_TRANSITION_DISABLE);
>>
>> /* Wait for shutdown to complete */
>> flush_work(&mhi_cntrl->st_worker);
>>
>> disable_irq(mhi_cntrl->irq[0]);
>> }
>> +
>> +void mhi_power_down(struct mhi_controller *mhi_cntrl, bool graceful)
>> +{
>> + __mhi_power_down(mhi_cntrl, graceful, true);
>> +}
>> EXPORT_SYMBOL_GPL(mhi_power_down);
>>
>> +void mhi_power_down_keep_dev(struct mhi_controller *mhi_cntrl,
>> + bool graceful)
>> +{
>> + __mhi_power_down(mhi_cntrl, graceful, false);
>> +}
>> +EXPORT_SYMBOL_GPL(mhi_power_down_keep_dev);
>> +
>> int mhi_sync_power_up(struct mhi_controller *mhi_cntrl)
>> {
>> int ret = mhi_async_power_up(mhi_cntrl);
>> diff --git a/include/linux/mhi.h b/include/linux/mhi.h
>> index 77b8c0a26674..cde01e133a1b 100644
>> --- a/include/linux/mhi.h
>> +++ b/include/linux/mhi.h
>> @@ -630,12 +630,28 @@ int mhi_async_power_up(struct mhi_controller *mhi_cntrl);
>> int mhi_sync_power_up(struct mhi_controller *mhi_cntrl);
>>
>> /**
>> - * mhi_power_down - Start MHI power down sequence
>> + * mhi_power_down - Power down the MHI device and also destroy the
>> + * 'struct device' for the channels associated with it.
>> + * See also mhi_power_down_keep_dev() which is a variant
>> + * of this API that keeps the 'struct device' for channels
>> + * (useful during suspend/hibernation).
>> * @mhi_cntrl: MHI controller
>> * @graceful: Link is still accessible, so do a graceful shutdown process
>> */
>> void mhi_power_down(struct mhi_controller *mhi_cntrl, bool graceful);
>>
>> +/**
>> + * mhi_power_down_keep_dev - Power down the MHI device but keep the 'struct
>> + * device' for the channels associated with it.
>> + * This is a variant of 'mhi_power_down()' and
>> + * useful in scenarios such as suspend/hibernation
>> + * where destroying of the 'struct device' is not
>> + * needed.
>> + * @mhi_cntrl: MHI controller
>> + * @graceful: Link is still accessible, so do a graceful shutdown process
>> + */
>> +void mhi_power_down_keep_dev(struct mhi_controller *mhi_cntrl, bool graceful);
>> +
>> /**
>> * mhi_unprepare_after_power_down - Free any allocated memory after power down
>> * @mhi_cntrl: MHI controller
>> --
>> 2.25.1
>>
>
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