Re: [PATCH 4/4] drm/tegra: Refactor IOMMU attach/detach

[Thierry Reding <thierry.reding@gmail.com>]

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On Fri, May 04, 2018 at 06:17:45PM +0300, Dmitry Osipenko wrote:
> On 04.05.2018 18:10, Thierry Reding wrote:
> > On Fri, May 04, 2018 at 05:23:42PM +0300, Dmitry Osipenko wrote:
> >> On 04.05.2018 16:37, Thierry Reding wrote:
> >>> From: Thierry Reding <treding@nvidia.com>
> >>>
> >>> Attaching to and detaching from an IOMMU uses the same code sequence in
> >>> every driver, so factor it out into separate helpers.
> >>>
> >>> Signed-off-by: Thierry Reding <treding@nvidia.com>
> >>> ---
> >>>  drivers/gpu/drm/tegra/dc.c   | 42 ++++++------------------------------
> >>>  drivers/gpu/drm/tegra/drm.c  | 42 ++++++++++++++++++++++++++++++++++++
> >>>  drivers/gpu/drm/tegra/drm.h  |  4 ++++
> >>>  drivers/gpu/drm/tegra/gr2d.c | 32 +++++++--------------------
> >>>  drivers/gpu/drm/tegra/gr3d.c | 31 ++++++--------------------
> >>>  5 files changed, 68 insertions(+), 83 deletions(-)
> >>>
> >>> diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c
> >>> index c843f11043db..3e7ec3937346 100644
> >>> --- a/drivers/gpu/drm/tegra/dc.c
> >>> +++ b/drivers/gpu/drm/tegra/dc.c
> >>> @@ -1837,21 +1837,11 @@ static int tegra_dc_init(struct host1x_client *client)
> >>>  	if (!dc->syncpt)
> >>>  		dev_warn(dc->dev, "failed to allocate syncpoint\n");
> >>>  
> >>> -	if (tegra->domain) {
> >>> -		dc->group = iommu_group_get(client->dev);
> >>> -
> >>> -		if (dc->group && dc->group != tegra->group) {
> >>> -			err = iommu_attach_group(tegra->domain, dc->group);
> >>> -			if (err < 0) {
> >>> -				dev_err(dc->dev,
> >>> -					"failed to attach to domain: %d\n",
> >>> -					err);
> >>> -				iommu_group_put(dc->group);
> >>> -				return err;
> >>> -			}
> >>> -
> >>> -			tegra->group = dc->group;
> >>> -		}
> >>> +	dc->group = host1x_client_iommu_attach(client, true);
> >>> +	if (IS_ERR(dc->group)) {
> >>> +		err = PTR_ERR(dc->group);
> >>> +		dev_err(client->dev, "failed to attach to domain: %d\n", err);
> >>> +		return err;
> >>>  	}
> >>>  
> >>>  	if (dc->soc->wgrps)
> >>> @@ -1916,15 +1906,7 @@ static int tegra_dc_init(struct host1x_client *client)
> >>>  	if (!IS_ERR(primary))
> >>>  		drm_plane_cleanup(primary);
> >>>  
> >>> -	if (dc->group) {
> >>> -		if (dc->group == tegra->group) {
> >>> -			iommu_detach_group(tegra->domain, dc->group);
> >>> -			tegra->group = NULL;
> >>> -		}
> >>> -
> >>> -		iommu_group_put(dc->group);
> >>> -	}
> >>> -
> >>> +	host1x_client_iommu_detach(client, dc->group);
> >>>  	host1x_syncpt_free(dc->syncpt);
> >>>  
> >>>  	return err;
> >>> @@ -1932,9 +1914,7 @@ static int tegra_dc_init(struct host1x_client *client)
> >>>  
> >>>  static int tegra_dc_exit(struct host1x_client *client)
> >>>  {
> >>> -	struct drm_device *drm = dev_get_drvdata(client->parent);
> >>>  	struct tegra_dc *dc = host1x_client_to_dc(client);
> >>> -	struct tegra_drm *tegra = drm->dev_private;
> >>>  	int err;
> >>>  
> >>>  	devm_free_irq(dc->dev, dc->irq, dc);
> >>> @@ -1945,15 +1925,7 @@ static int tegra_dc_exit(struct host1x_client *client)
> >>>  		return err;
> >>>  	}
> >>>  
> >>> -	if (dc->group) {
> >>> -		if (dc->group == tegra->group) {
> >>> -			iommu_detach_group(tegra->domain, dc->group);
> >>> -			tegra->group = NULL;
> >>> -		}
> >>> -
> >>> -		iommu_group_put(dc->group);
> >>> -	}
> >>> -
> >>> +	host1x_client_iommu_detach(client, dc->group);
> >>>  	host1x_syncpt_free(dc->syncpt);
> >>>  
> >>>  	return 0;
> >>> diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
> >>> index 7afe2f635f74..bc1008305e1e 100644
> >>> --- a/drivers/gpu/drm/tegra/drm.c
> >>> +++ b/drivers/gpu/drm/tegra/drm.c
> >>> @@ -1114,6 +1114,48 @@ int tegra_drm_unregister_client(struct tegra_drm *tegra,
> >>>  	return 0;
> >>>  }
> >>>  
> >>> +struct iommu_group *host1x_client_iommu_attach(struct host1x_client *client,
> >>> +					       bool shared)
> >>> +{
> >>> +	struct drm_device *drm = dev_get_drvdata(client->parent);
> >>> +	struct tegra_drm *tegra = drm->dev_private;
> >>> +	struct iommu_group *group = NULL;
> >>> +	int err;
> >>> +
> >>> +	if (tegra->domain) {
> >>> +		group = iommu_group_get(client->dev);
> >>> +
> >>> +		if (group && (!shared || (shared && (group != tegra->group)))) {
> >>> +			err = iommu_attach_group(tegra->domain, group);
> >>> +			if (err < 0) {
> >>> +				iommu_group_put(group);
> >>> +				return ERR_PTR(err);
> >>> +			}
> >>> +
> >>> +			if (shared && !tegra->group)
> >>> +				tegra->group = group;
> >>> +		}
> >>> +	}
> >>> +
> >>> +	return group;
> >>> +}
> >>> +
> >>> +void host1x_client_iommu_detach(struct host1x_client *client,
> >>> +				struct iommu_group *group)
> >>> +{
> >>> +	struct drm_device *drm = dev_get_drvdata(client->parent);
> >>> +	struct tegra_drm *tegra = drm->dev_private;
> >>> +
> >>> +	if (group) {
> >>> +		if (group == tegra->group) {
> >>> +			iommu_detach_group(tegra->domain, group);
> >>> +			tegra->group = NULL;
> >>> +		}
> >>> +
> >>> +		iommu_group_put(group);
> >>> +	}
> >>> +}
> >>> +
> >>>  void *tegra_drm_alloc(struct tegra_drm *tegra, size_t size, dma_addr_t *dma)
> >>>  {
> >>>  	struct iova *alloc;
> >>> diff --git a/drivers/gpu/drm/tegra/drm.h b/drivers/gpu/drm/tegra/drm.h
> >>> index 4f41aaec8530..fe263cf58f34 100644
> >>> --- a/drivers/gpu/drm/tegra/drm.h
> >>> +++ b/drivers/gpu/drm/tegra/drm.h
> >>> @@ -110,6 +110,10 @@ int tegra_drm_register_client(struct tegra_drm *tegra,
> >>>  			      struct tegra_drm_client *client);
> >>>  int tegra_drm_unregister_client(struct tegra_drm *tegra,
> >>>  				struct tegra_drm_client *client);
> >>> +struct iommu_group *host1x_client_iommu_attach(struct host1x_client *client,
> >>> +					       bool shared);
> >>> +void host1x_client_iommu_detach(struct host1x_client *client,
> >>> +				struct iommu_group *group);
> >>>  
> >>>  int tegra_drm_init(struct tegra_drm *tegra, struct drm_device *drm);
> >>>  int tegra_drm_exit(struct tegra_drm *tegra);
> >>> diff --git a/drivers/gpu/drm/tegra/gr2d.c b/drivers/gpu/drm/tegra/gr2d.c
> >>> index 0b42e99da8ad..2cd0f66c8aa9 100644
> >>> --- a/drivers/gpu/drm/tegra/gr2d.c
> >>> +++ b/drivers/gpu/drm/tegra/gr2d.c
> >>> @@ -32,7 +32,6 @@ static int gr2d_init(struct host1x_client *client)
> >>>  	struct tegra_drm_client *drm = host1x_to_drm_client(client);
> >>>  	struct drm_device *dev = dev_get_drvdata(client->parent);
> >>>  	unsigned long flags = HOST1X_SYNCPT_HAS_BASE;
> >>> -	struct tegra_drm *tegra = dev->dev_private;
> >>>  	struct gr2d *gr2d = to_gr2d(drm);
> >>>  	int err;
> >>>  
> >>> @@ -47,22 +46,14 @@ static int gr2d_init(struct host1x_client *client)
> >>>  		goto put;
> >>>  	}
> >>>  
> >>> -	if (tegra->domain) {
> >>> -		gr2d->group = iommu_group_get(client->dev);
> >>> -
> >>> -		if (gr2d->group) {
> >>> -			err = iommu_attach_group(tegra->domain, gr2d->group);
> >>> -			if (err < 0) {
> >>> -				dev_err(client->dev,
> >>> -					"failed to attach to domain: %d\n",
> >>> -					err);
> >>> -				iommu_group_put(gr2d->group);
> >>> -				goto free;
> >>> -			}
> >>> -		}
> >>> +	gr2d->group = host1x_client_iommu_attach(client, false);
> >>> +	if (IS_ERR(gr2d->group)) {
> >>> +		err = PTR_ERR(gr2d->group);
> >>> +		dev_err(client->dev, "failed to attach to domain: %d\n", err);
> >>> +		goto free;
> >>>  	}
> >>>  
> >>> -	err = tegra_drm_register_client(tegra, drm);
> >>> +	err = tegra_drm_register_client(dev->dev_private, drm);
> >>>  	if (err < 0) {
> >>>  		dev_err(client->dev, "failed to register client: %d\n", err);
> >>>  		goto detach;
> >>> @@ -71,10 +62,7 @@ static int gr2d_init(struct host1x_client *client)
> >>>  	return 0;
> >>>  
> >>>  detach:
> >>> -	if (gr2d->group) {
> >>> -		iommu_detach_group(tegra->domain, gr2d->group);
> >>> -		iommu_group_put(gr2d->group);
> >>> -	}
> >>> +	host1x_client_iommu_detach(client, gr2d->group);
> >>>  free:
> >>>  	host1x_syncpt_free(client->syncpts[0]);
> >>>  put:
> >>> @@ -94,14 +82,10 @@ static int gr2d_exit(struct host1x_client *client)
> >>>  	if (err < 0)
> >>>  		return err;
> >>>  
> >>> +	host1x_client_iommu_detach(client, gr2d->group);
> >>>  	host1x_syncpt_free(client->syncpts[0]);
> >>>  	host1x_channel_put(gr2d->channel);
> >>>  
> >>> -	if (gr2d->group) {
> >>> -		iommu_detach_group(tegra->domain, gr2d->group);
> >>> -		iommu_group_put(gr2d->group);
> >>> -	}
> >>> -
> >>>  	return 0;
> >>>  }
> >>>  
> >>> diff --git a/drivers/gpu/drm/tegra/gr3d.c b/drivers/gpu/drm/tegra/gr3d.c
> >>> index e129f1afff33..98e3c67d0fb5 100644
> >>> --- a/drivers/gpu/drm/tegra/gr3d.c
> >>> +++ b/drivers/gpu/drm/tegra/gr3d.c
> >>> @@ -42,7 +42,6 @@ static int gr3d_init(struct host1x_client *client)
> >>>  	struct tegra_drm_client *drm = host1x_to_drm_client(client);
> >>>  	struct drm_device *dev = dev_get_drvdata(client->parent);
> >>>  	unsigned long flags = HOST1X_SYNCPT_HAS_BASE;
> >>> -	struct tegra_drm *tegra = dev->dev_private;
> >>>  	struct gr3d *gr3d = to_gr3d(drm);
> >>>  	int err;
> >>>  
> >>> @@ -56,19 +55,11 @@ static int gr3d_init(struct host1x_client *client)
> >>>  		goto put;
> >>>  	}
> >>>  
> >>> -	if (tegra->domain) {
> >>> -		gr3d->group = iommu_group_get(client->dev);
> >>> -
> >>> -		if (gr3d->group) {
> >>> -			err = iommu_attach_group(tegra->domain, gr3d->group);
> >>> -			if (err < 0) {
> >>> -				dev_err(client->dev,
> >>> -					"failed to attach to domain: %d\n",
> >>> -					err);
> >>> -				iommu_group_put(gr3d->group);
> >>> -				goto free;
> >>> -			}
> >>> -		}
> >>> +	gr3d->group = host1x_client_iommu_attach(client, false);
> >>> +	if (IS_ERR(gr3d->group)) {
> >>> +		err = PTR_ERR(gr3d->group);
> >>> +		dev_err(client->dev, "failed to attach to domain: %d\n", err);
> >>> +		goto free;
> >>>  	}
> >>>  
> >>>  	err = tegra_drm_register_client(dev->dev_private, drm);
> >>> @@ -80,10 +71,7 @@ static int gr3d_init(struct host1x_client *client)
> >>>  	return 0;
> >>>  
> >>>  detach:
> >>> -	if (gr3d->group) {
> >>> -		iommu_detach_group(tegra->domain, gr3d->group);
> >>> -		iommu_group_put(gr3d->group);
> >>> -	}
> >>> +	host1x_client_iommu_detach(client, gr3d->group);
> >>>  free:
> >>>  	host1x_syncpt_free(client->syncpts[0]);
> >>>  put:
> >>> @@ -95,7 +83,6 @@ static int gr3d_exit(struct host1x_client *client)
> >>>  {
> >>>  	struct tegra_drm_client *drm = host1x_to_drm_client(client);
> >>>  	struct drm_device *dev = dev_get_drvdata(client->parent);
> >>> -	struct tegra_drm *tegra = dev->dev_private;
> >>>  	struct gr3d *gr3d = to_gr3d(drm);
> >>>  	int err;
> >>>  
> >>> @@ -103,14 +90,10 @@ static int gr3d_exit(struct host1x_client *client)
> >>>  	if (err < 0)
> >>>  		return err;
> >>>  
> >>> +	host1x_client_iommu_detach(client, gr3d->group);
> >>>  	host1x_syncpt_free(client->syncpts[0]);
> >>>  	host1x_channel_put(gr3d->channel);
> >>>  
> >>> -	if (gr3d->group) {
> >>> -		iommu_detach_group(tegra->domain, gr3d->group);
> >>> -		iommu_group_put(gr3d->group);
> >>> -	}
> >>> -
> >>>  	return 0;
> >>>  }
> >>>  
> >>>
> >>
> >> Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
> >>
> >> Though I'd prefer to have tegra->group renamed, maybe to 'shared_dc_group'.
> > 
> > tegra->group doesn't bother me at all. I think just the fact that it's
> > in struct tegra_drm implies that it is shared. It's also declared
> > closely to all the other "shared" variables, so I think that makes it
> > pretty clear. If there were other IOMMU groups I'd agree that renaming
> > it would be good to clarify the purpose. But as it is, I think there's
> > no need for that.
> > 
> > Thanks for the review!
> 
> Well, okay. On the other hand IOMMU API should handle re-attaching from a
> different device and then that shared group isn't needed at all. Does that
> re-attaching cause any problems right now? If yes, maybe it's worth fixing the
> root of the problem rather than trying to workaround it.

Agreed. I've got that on my TODO list somewhere, let me bump that up a
little.

Thierry

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