Re: [PATCH] drm/msm: Initialize MDSS irq domain at probe time

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

On 25/11/2021 18:09, AngeloGioacchino Del Regno wrote:
> Since commit 8f59ee9a570c ("drm/msm/dsi: Adjust probe order"), the
> DSI host gets initialized earlier, but this caused unability to probe
> the entire stack of components because they all depend on interrupts
> coming from the main `mdss` node (mdp5, or dpu1).
> 
> To fix this issue, also anticipate probing mdp5 or dpu1 by initializing
> them at msm_pdev_probe() time: this will make sure that we add the
> required interrupt controller mapping before dsi and/or other components
> try to initialize, finally satisfying the dependency.
> 
> While at it, also change the allocation of msm_drm_private to use the
> devm variant of kzalloc().
> 
> Fixes: 8f59ee9a570c ("drm/msm/dsi: Adjust probe order")
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

If device is not fully bound (e.g. DSI host could not bind the panel), 
this patch causes the following oops on reboot:

[   75.011942] Unable to handle kernel NULL pointer dereference at 
virtual address 0000000000000030
[   75.020974] Mem abort info:
[   75.023859]   ESR = 0x96000006
[   75.027013]   EC = 0x25: DABT (current EL), IL = 32 bits
[   75.032480]   SET = 0, FnV = 0
[   75.035627]   EA = 0, S1PTW = 0
[   75.038861]   FSC = 0x06: level 2 translation fault
[   75.043876] Data abort info:
[   75.046847]   ISV = 0, ISS = 0x00000006
[   75.050796]   CM = 0, WnR = 0
[   75.053857] user pgtable: 4k pages, 48-bit VAs, pgdp=00000001102b3000
[   75.060478] [0000000000000030] pgd=080000011035d003, 
p4d=080000011035d003, pud=080000011035f003, pmd=0000000000000000
[   75.071380] Internal error: Oops: 96000006 [#1] SMP
[   75.076388] Modules linked in:
[   75.079530] CPU: 0 PID: 1442 Comm: reboot Not tainted 
5.16.0-rc1-00046-g2207fd610cf4-dirty #185
[   75.088460] Hardware name: Qualcomm Technologies, Inc. Robotics RB5 (DT)
[   75.095345] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS 
BTYPE=--)
[   75.102496] pc : drm_atomic_state_alloc+0x14/0x74
[   75.107335] lr : drm_atomic_helper_disable_all+0x20/0x210
[   75.112885] sp : ffff80001480bb70
[   75.116298] x29: ffff80001480bb70 x28: ffff0c8753505400 x27: 
0000000000000000
[   75.123626] x26: ffff0c874097d890 x25: ffffaa357b610e00 x24: 
0000000000000000
[   75.130954] x23: ffffaa357bdaa030 x22: ffffaa357bdfd2d8 x21: 
ffff80001480bbf8
[   75.138282] x20: ffff0c87469bd800 x19: ffff0c87469bd800 x18: 
ffffffffffffffff
[   75.145608] x17: 000000000000000e x16: 0000000000000001 x15: 
ffff80009480ba3d
[   75.152934] x14: 0000000000000004 x13: 0000000000000000 x12: 
ffff0c87452c1288
[   75.160261] x11: 0000000000000003 x10: ffff0c87452c1240 x9 : 
0000000000000001
[   75.167588] x8 : ffff80001480bc38 x7 : 0000000000000000 x6 : 
ffff0c874f63d300
[   75.174914] x5 : 0000000000000000 x4 : ffffaa357b582d30 x3 : 
0000000000000000
[   75.182240] x2 : ffff80001480bc20 x1 : 0000000000000000 x0 : 
ffff0c87469bd800
[   75.189568] Call trace:
[   75.192092]  drm_atomic_state_alloc+0x14/0x74
[   75.196571]  drm_atomic_helper_disable_all+0x20/0x210
[   75.201765]  drm_atomic_helper_shutdown+0x80/0x130
[   75.206683]  msm_pdev_shutdown+0x2c/0x40
[   75.210717]  platform_shutdown+0x28/0x40
[   75.214751]  device_shutdown+0x15c/0x450
[   75.218785]  __do_sys_reboot+0x218/0x2a0
[   75.222819]  __arm64_sys_reboot+0x28/0x34
[   75.226937]  invoke_syscall+0x48/0x114
[   75.230794]  el0_svc_common.constprop.0+0xd4/0xfc
[   75.235626]  do_el0_svc+0x28/0x90
[   75.239030]  el0_svc+0x28/0x80
[   75.242174]  el0t_64_sync_handler+0xa4/0x130
[   75.246567]  el0t_64_sync+0x1a0/0x1a4
[   75.250338] Code: a9be7bfd 910003fd a90153f3 f9418c01 (f9401821)
[   75.256599] ---[ end trace d90b41486de58d22 ]---


The following patch fixes it:

diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index 41c6a9f9dd34..5a92417d21d0 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -1435,7 +1435,7 @@ static void msm_pdev_shutdown(struct
         struct drm_device *drm = platform_get_drvdata(pdev);
         struct msm_drm_private *priv = drm ? drm->dev_private : NULL;

-       if (!priv || !priv->kms)
+       if (!priv || !priv->kms || !drm->mode_config.funcs)
                 return;

         drm_atomic_helper_shutdown(drm);


> ---
>   drivers/gpu/drm/msm/msm_drv.c | 81 ++++++++++++++++-------------------
>   1 file changed, 38 insertions(+), 43 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
> index 7936e8d498dd..790acf4993c0 100644
> --- a/drivers/gpu/drm/msm/msm_drv.c
> +++ b/drivers/gpu/drm/msm/msm_drv.c
> @@ -512,45 +512,12 @@ static int msm_init_vram(struct drm_device *dev)
>   static int msm_drm_init(struct device *dev, const struct drm_driver *drv)
>   {
>   	struct platform_device *pdev = to_platform_device(dev);
> -	struct drm_device *ddev;
> -	struct msm_drm_private *priv;
> -	struct msm_kms *kms;
> -	struct msm_mdss *mdss;
> +	struct drm_device *ddev = platform_get_drvdata(pdev);
> +	struct msm_drm_private *priv = ddev->dev_private;
> +	struct msm_kms *kms = priv->kms;
> +	struct msm_mdss *mdss = priv->mdss;
>   	int ret, i;
>   
> -	ddev = drm_dev_alloc(drv, dev);
> -	if (IS_ERR(ddev)) {
> -		DRM_DEV_ERROR(dev, "failed to allocate drm_device\n");
> -		return PTR_ERR(ddev);
> -	}
> -
> -	platform_set_drvdata(pdev, ddev);
> -
> -	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
> -	if (!priv) {
> -		ret = -ENOMEM;
> -		goto err_put_drm_dev;
> -	}
> -
> -	ddev->dev_private = priv;
> -	priv->dev = ddev;
> -
> -	switch (get_mdp_ver(pdev)) {
> -	case KMS_MDP5:
> -		ret = mdp5_mdss_init(ddev);
> -		break;
> -	case KMS_DPU:
> -		ret = dpu_mdss_init(ddev);
> -		break;
> -	default:
> -		ret = 0;
> -		break;
> -	}
> -	if (ret)
> -		goto err_free_priv;
> -
> -	mdss = priv->mdss;
> -
>   	priv->wq = alloc_ordered_workqueue("msm", 0);
>   	priv->hangcheck_period = DRM_MSM_HANGCHECK_DEFAULT_PERIOD;
>   
> @@ -685,11 +652,6 @@ static int msm_drm_init(struct device *dev, const struct drm_driver *drv)
>   err_destroy_mdss:
>   	if (mdss && mdss->funcs)
>   		mdss->funcs->destroy(ddev);
> -err_free_priv:
> -	kfree(priv);
> -err_put_drm_dev:
> -	drm_dev_put(ddev);
> -	platform_set_drvdata(pdev, NULL);
>   	return ret;
>   }
>   
> @@ -1382,12 +1344,42 @@ static const struct component_master_ops msm_drm_ops = {
>   static int msm_pdev_probe(struct platform_device *pdev)
>   {
>   	struct component_match *match = NULL;
> +	struct msm_drm_private *priv;
> +	struct drm_device *ddev;
>   	int ret;
>   
> +	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	ddev = drm_dev_alloc(&msm_driver, &pdev->dev);
> +	if (IS_ERR(ddev)) {
> +		DRM_DEV_ERROR(&pdev->dev, "failed to allocate drm_device\n");
> +		return PTR_ERR(ddev);
> +	}
> +
> +	platform_set_drvdata(pdev, ddev);
> +	ddev->dev_private = priv;
> +	priv->dev = ddev;
> +
> +	switch (get_mdp_ver(pdev)) {
> +	case KMS_MDP5:
> +		ret = mdp5_mdss_init(ddev);
> +		break;
> +	case KMS_DPU:
> +		ret = dpu_mdss_init(ddev);
> +		break;
> +	default:
> +		ret = 0;
> +		break;
> +	}
> +	if (ret)
> +		goto err_put_drm_dev;
> +
>   	if (get_mdp_ver(pdev)) {
>   		ret = add_display_components(pdev, &match);
>   		if (ret)
> -			return ret;
> +			goto fail;
>   	}
>   
>   	ret = add_gpu_components(&pdev->dev, &match);
> @@ -1409,6 +1401,9 @@ static int msm_pdev_probe(struct platform_device *pdev)
>   
>   fail:
>   	of_platform_depopulate(&pdev->dev);
> +err_put_drm_dev:
> +	drm_dev_put(ddev);
> +	platform_set_drvdata(pdev, NULL);
>   	return ret;
>   }
>   
> 


-- 
With best wishes
Dmitry