[RFC PATCH 1/4] drm/msm: register a fault handler for display mmu faults

[Abhinav Kumar]

On 5/19/2024 1:31 AM, Dmitry Baryshkov wrote:
> On Fri, May 17, 2024 at 04:37:56PM -0700, Abhinav Kumar wrote:
>> In preparation to register a iommu fault handler for display
>> related modules, register a fault handler for the backing
>> mmu object of msm_kms.
>>
>> Currently, the fault handler only captures the display snapshot
>> but we can expand this later if more information needs to be
>> added to debug display mmu faults.
>>
>> Signed-off-by: Abhinav Kumar <quic_abhinavk at quicinc.com>
>> ---
>>   drivers/gpu/drm/msm/msm_kms.c | 25 +++++++++++++++++++++++++
>>   1 file changed, 25 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/msm/msm_kms.c b/drivers/gpu/drm/msm/msm_kms.c
>> index af6a6fcb1173..62c8e6163e81 100644
>> --- a/drivers/gpu/drm/msm/msm_kms.c
>> +++ b/drivers/gpu/drm/msm/msm_kms.c
>> @@ -200,6 +200,28 @@ struct msm_gem_address_space *msm_kms_init_aspace(struct drm_device *dev)
>>   	return aspace;
>>   }
>>   
>> +static int msm_kms_fault_handler(void *arg, unsigned long iova, int flags, void *data)
>> +{
>> +	struct msm_kms *kms = arg;
>> +	struct msm_disp_state *state;
>> +	int ret;
>> +
>> +	ret = mutex_lock_interruptible(&kms->dump_mutex);
>> +	if (ret)
>> +		return ret;
>> +
>> +	state = msm_disp_snapshot_state_sync(kms);
>> +
>> +	mutex_unlock(&kms->dump_mutex);
>> +
>> +	if (IS_ERR(state)) {
>> +		DRM_DEV_ERROR(kms->dev->dev, "failed to capture snapshot\n");
>> +		return PTR_ERR(state);
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>>   void msm_drm_kms_uninit(struct device *dev)
>>   {
>>   	struct platform_device *pdev = to_platform_device(dev);
>> @@ -261,6 +283,9 @@ int msm_drm_kms_init(struct device *dev, const struct drm_driver *drv)
>>   		goto err_msm_uninit;
>>   	}
>>   
>> +	if (kms->aspace)
>> +		msm_mmu_set_fault_handler(kms->aspace->mmu, kms, msm_kms_fault_handler);
>> +
> 
> Can we move this to msm_kms_init_aspace() instead of checking for
> kms->aspace?

Ack.
> 
>>   	drm_helper_move_panel_connectors_to_head(ddev);
>>   
>>   	drm_for_each_crtc(crtc, ddev) {
>> -- 
>> 2.44.0
>>
>