Re: [PATCH v6 1/4] bus: mhi: core: Destroy SBL devices when moving to mission mode

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Wed, Feb 24, 2021 at 03:23:02PM -0800, Bhaumik Bhatt wrote:
> Currently, client devices are created in SBL or AMSS (mission
> mode) and only destroyed after power down or SYS ERROR. When
> moving between certain execution environments, such as from SBL
> to AMSS, no clean-up is required. This presents an issue where
> SBL-specific channels are left open and client drivers now run in
> an execution environment where they cannot operate. Fix this by
> expanding the mhi_destroy_device() to do an execution environment
> specific clean-up if one is requested. Close the gap and destroy
> devices in such scenarios that allow SBL client drivers to clean
> up once device enters mission mode.
> 
> Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Thanks,
Mani

> ---
>  drivers/bus/mhi/core/main.c | 29 +++++++++++++++++++++++++----
>  drivers/bus/mhi/core/pm.c   |  3 +++
>  2 files changed, 28 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
> index 4e0131b..7a2e98c 100644
> --- a/drivers/bus/mhi/core/main.c
> +++ b/drivers/bus/mhi/core/main.c
> @@ -244,8 +244,10 @@ static void mhi_del_ring_element(struct mhi_controller *mhi_cntrl,
>  
>  int mhi_destroy_device(struct device *dev, void *data)
>  {
> +	struct mhi_chan *ul_chan, *dl_chan;
>  	struct mhi_device *mhi_dev;
>  	struct mhi_controller *mhi_cntrl;
> +	enum mhi_ee_type ee = MHI_EE_MAX;
>  
>  	if (dev->bus != &mhi_bus_type)
>  		return 0;
> @@ -257,6 +259,17 @@ int mhi_destroy_device(struct device *dev, void *data)
>  	if (mhi_dev->dev_type == MHI_DEVICE_CONTROLLER)
>  		return 0;
>  
> +	ul_chan = mhi_dev->ul_chan;
> +	dl_chan = mhi_dev->dl_chan;
> +
> +	/*
> +	 * If execution environment is specified, remove only those devices that
> +	 * started in them based on ee_mask for the channels as we move on to a
> +	 * different execution environment
> +	 */
> +	if (data)
> +		ee = *(enum mhi_ee_type *)data;
> +
>  	/*
>  	 * For the suspend and resume case, this function will get called
>  	 * without mhi_unregister_controller(). Hence, we need to drop the
> @@ -264,11 +277,19 @@ int mhi_destroy_device(struct device *dev, void *data)
>  	 * be sure that there will be no instances of mhi_dev left after
>  	 * this.
>  	 */
> -	if (mhi_dev->ul_chan)
> -		put_device(&mhi_dev->ul_chan->mhi_dev->dev);
> +	if (ul_chan) {
> +		if (ee != MHI_EE_MAX && !(ul_chan->ee_mask & BIT(ee)))
> +			return 0;
>  
> -	if (mhi_dev->dl_chan)
> -		put_device(&mhi_dev->dl_chan->mhi_dev->dev);
> +		put_device(&ul_chan->mhi_dev->dev);
> +	}
> +
> +	if (dl_chan) {
> +		if (ee != MHI_EE_MAX && !(dl_chan->ee_mask & BIT(ee)))
> +			return 0;
> +
> +		put_device(&dl_chan->mhi_dev->dev);
> +	}
>  
>  	dev_dbg(&mhi_cntrl->mhi_dev->dev, "destroy device for chan:%s\n",
>  		 mhi_dev->name);
> diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
> index 681960c..3bd81d0 100644
> --- a/drivers/bus/mhi/core/pm.c
> +++ b/drivers/bus/mhi/core/pm.c
> @@ -377,6 +377,7 @@ static int mhi_pm_mission_mode_transition(struct mhi_controller *mhi_cntrl)
>  {
>  	struct mhi_event *mhi_event;
>  	struct device *dev = &mhi_cntrl->mhi_dev->dev;
> +	enum mhi_ee_type current_ee = mhi_cntrl->ee;
>  	int i, ret;
>  
>  	dev_dbg(dev, "Processing Mission Mode transition\n");
> @@ -395,6 +396,8 @@ static int mhi_pm_mission_mode_transition(struct mhi_controller *mhi_cntrl)
>  
>  	wake_up_all(&mhi_cntrl->state_event);
>  
> +	device_for_each_child(&mhi_cntrl->mhi_dev->dev, &current_ee,
> +			      mhi_destroy_device);
>  	mhi_cntrl->status_cb(mhi_cntrl, MHI_CB_EE_MISSION_MODE);
>  
>  	/* Force MHI to be in M0 state before continuing */
> -- 
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>