diff mbox

drm/vc4: Fix refcounting of runtime PM get if it errors out.

Message ID 20170417162603.12726-1-eric@anholt.net (mailing list archive)
State New, archived
Headers show

Commit Message

Eric Anholt April 17, 2017, 4:26 p.m. UTC
We were returning without decrementing if the error happened, meaning
that at the next submit we wouldn't try to bring up the power domain.

Signed-off-by: Eric Anholt <eric@anholt.net>
---

I stumbled across this error when testing my CMA patch with a very low
(64MB) CMA area -- we would oops on the submit after the one that
failed.

 drivers/gpu/drm/vc4/vc4_gem.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

Comments

Sean Paul April 17, 2017, 5:58 p.m. UTC | #1
On Mon, Apr 17, 2017 at 09:26:03AM -0700, Eric Anholt wrote:
> We were returning without decrementing if the error happened, meaning
> that at the next submit we wouldn't try to bring up the power domain.
> 
> Signed-off-by: Eric Anholt <eric@anholt.net>

This change looks good to me. It seems a little odd to wrap pm_runtime which
is already refcounted in another refcount, but I'm really not familiar with
the driver, and I'm sure there's a good reason for it.

Reviewed-by: Sean Paul <seanpaul@chromium.org>

> ---
> 
> I stumbled across this error when testing my CMA patch with a very low
> (64MB) CMA area -- we would oops on the submit after the one that
> failed.
> 
>  drivers/gpu/drm/vc4/vc4_gem.c | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vc4/vc4_gem.c b/drivers/gpu/drm/vc4/vc4_gem.c
> index 777a8d9afd60..735412e3725a 100644
> --- a/drivers/gpu/drm/vc4/vc4_gem.c
> +++ b/drivers/gpu/drm/vc4/vc4_gem.c
> @@ -1016,13 +1016,16 @@ vc4_submit_cl_ioctl(struct drm_device *dev, void *data,
>  	}
>  
>  	mutex_lock(&vc4->power_lock);
> -	if (vc4->power_refcount++ == 0)
> +	if (vc4->power_refcount++ == 0) {
>  		ret = pm_runtime_get_sync(&vc4->v3d->pdev->dev);
> -	mutex_unlock(&vc4->power_lock);
> -	if (ret < 0) {
> -		kfree(exec);
> -		return ret;
> +		if (ret < 0) {
> +			mutex_unlock(&vc4->power_lock);
> +			vc4->power_refcount--;
> +			kfree(exec);
> +			return ret;
> +		}
>  	}
> +	mutex_unlock(&vc4->power_lock);
>  
>  	exec->args = args;
>  	INIT_LIST_HEAD(&exec->unref_list);
> -- 
> 2.11.0
Eric Anholt April 17, 2017, 8:32 p.m. UTC | #2
Sean Paul <seanpaul@chromium.org> writes:

> On Mon, Apr 17, 2017 at 09:26:03AM -0700, Eric Anholt wrote:
>> We were returning without decrementing if the error happened, meaning
>> that at the next submit we wouldn't try to bring up the power domain.
>> 
>> Signed-off-by: Eric Anholt <eric@anholt.net>
>
> This change looks good to me. It seems a little odd to wrap pm_runtime which
> is already refcounted in another refcount, but I'm really not familiar with
> the driver, and I'm sure there's a good reason for it.
>
> Reviewed-by: Sean Paul <seanpaul@chromium.org>

Yeah, it's an unfortunate hack because the reset control is buried in
the power domain driver on the RPi, so we have to get the power domain
actually off (0 refcount) in order to reset the GPU.

Yay for building around closed-source firmware :(
diff mbox

Patch

diff --git a/drivers/gpu/drm/vc4/vc4_gem.c b/drivers/gpu/drm/vc4/vc4_gem.c
index 777a8d9afd60..735412e3725a 100644
--- a/drivers/gpu/drm/vc4/vc4_gem.c
+++ b/drivers/gpu/drm/vc4/vc4_gem.c
@@ -1016,13 +1016,16 @@  vc4_submit_cl_ioctl(struct drm_device *dev, void *data,
 	}
 
 	mutex_lock(&vc4->power_lock);
-	if (vc4->power_refcount++ == 0)
+	if (vc4->power_refcount++ == 0) {
 		ret = pm_runtime_get_sync(&vc4->v3d->pdev->dev);
-	mutex_unlock(&vc4->power_lock);
-	if (ret < 0) {
-		kfree(exec);
-		return ret;
+		if (ret < 0) {
+			mutex_unlock(&vc4->power_lock);
+			vc4->power_refcount--;
+			kfree(exec);
+			return ret;
+		}
 	}
+	mutex_unlock(&vc4->power_lock);
 
 	exec->args = args;
 	INIT_LIST_HEAD(&exec->unref_list);