Nouveau - Feb 2014 - [PATCH] drm/nouveau: handle -EACCES runtime PM return code

pm_runtime_get*() may return -EACCESS to indicate a device does not have
runtime PM enabled. This is the case when the nouveau.runpm parameter is
set to 0, and is not an error in that context. Handle this case without
failure.

Signed-off-by: Alexandre Courbot <acourbot at nvidia.com>
---
 drivers/gpu/drm/nouveau/dispnv04/crtc.c     | 2 +-
 drivers/gpu/drm/nouveau/nouveau_connector.c | 2 +-
 drivers/gpu/drm/nouveau/nouveau_drm.c       | 4 ++--
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/dispnv04/crtc.c
b/drivers/gpu/drm/nouveau/dispnv04/crtc.c
index 0e3270c3ffd2..1caef1fd139e 100644
--- a/drivers/gpu/drm/nouveau/dispnv04/crtc.c
+++ b/drivers/gpu/drm/nouveau/dispnv04/crtc.c
@@ -1048,7 +1048,7 @@ nouveau_crtc_set_config(struct drm_mode_set *set)
 
 	/* get a pm reference here */
 	ret = pm_runtime_get_sync(dev->dev);
-	if (ret < 0)
+	if (ret < 0 && ret != -EACCES)
 		return ret;
 
 	ret = drm_crtc_helper_set_config(set);
diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c
b/drivers/gpu/drm/nouveau/nouveau_connector.c
index 1674882d60d5..cddef546d9b0 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -255,7 +255,7 @@ nouveau_connector_detect(struct drm_connector *connector,
bool force)
 	}
 
 	ret = pm_runtime_get_sync(connector->dev->dev);
-	if (ret < 0)
+	if (ret < 0 && ret != -EACCES)
 		return conn_status;
 
 	i2c = nouveau_connector_ddc_detect(connector, &nv_encoder);
diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c
b/drivers/gpu/drm/nouveau/nouveau_drm.c
index 8a4630a1fc45..2617168af244 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
@@ -696,7 +696,7 @@ nouveau_drm_open(struct drm_device *dev, struct drm_file
*fpriv)
 
 	/* need to bring up power immediately if opening device */
 	ret = pm_runtime_get_sync(dev->dev);
-	if (ret < 0)
+	if (ret < 0 && ret != -EACCES)
 		return ret;
 
 	get_task_comm(tmpname, current);
@@ -781,7 +781,7 @@ long nouveau_drm_ioctl(struct file *filp,
 	dev = file_priv->minor->dev;
 
 	ret = pm_runtime_get_sync(dev->dev);
-	if (ret < 0)
+	if (ret < 0 && ret != -EACCES)
 		return ret;
 
 	ret = drm_ioctl(filp, cmd, arg);
-- 
1.8.5.4

On Mon, Feb 10, 2014 at 02:58:12PM +0900, Alexandre Courbot
wrote:
> pm_runtime_get*() may return -EACCESS to indicate a device does not have
s/-EACCESS/-EACCES/
> runtime PM enabled. This is the case when the nouveau.runpm parameter is
> set to 0, and is not an error in that context. Handle this case without
> failure.
> 
> Signed-off-by: Alexandre Courbot <acourbot at nvidia.com>
> ---
>  drivers/gpu/drm/nouveau/dispnv04/crtc.c     | 2 +-
>  drivers/gpu/drm/nouveau/nouveau_connector.c | 2 +-
>  drivers/gpu/drm/nouveau/nouveau_drm.c       | 4 ++--
>  3 files changed, 4 insertions(+), 4 deletions(-)
I'm not sure if the commit message is entirely accurate. Looking at the
various runtime power-management functions in nouveau_drm.c (such as
nouveau_pmops_runtime_suspend() for example), they seem to return
-EINVAL if the nouveau.runpm parameter is set to 0.

However it seems like -EACCES is indeed returned when runtime power-
management hasn't been enabled for a device. This is done automatically
for PCI devices, but not for platform devices. We don't support runtime
power-management on gk20a yet, therefore pm_runtime_enable() is never
called, causing disable_depth to remain at -1 and therefore runtime PM
helpers return -EACCES.

Thierry
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On Mon, Feb 10, 2014 at 9:34 PM, Thierry Reding
<thierry.reding at gmail.com> wrote:
> On Mon, Feb 10, 2014 at 02:58:12PM +0900, Alexandre Courbot wrote:
>> pm_runtime_get*() may return -EACCESS to indicate a device does not
have
>
> s/-EACCESS/-EACCES/
Oops.
>> runtime PM enabled. This is the case when the nouveau.runpm parameter
is
>> set to 0, and is not an error in that context. Handle this case without
>> failure.
>>
>> Signed-off-by: Alexandre Courbot <acourbot at nvidia.com>
>> ---
>>  drivers/gpu/drm/nouveau/dispnv04/crtc.c     | 2 +-
>>  drivers/gpu/drm/nouveau/nouveau_connector.c | 2 +-
>>  drivers/gpu/drm/nouveau/nouveau_drm.c       | 4 ++--
>>  3 files changed, 4 insertions(+), 4 deletions(-)
>
> I'm not sure if the commit message is entirely accurate. Looking at the
> various runtime power-management functions in nouveau_drm.c (such as
> nouveau_pmops_runtime_suspend() for example), they seem to return
> -EINVAL if the nouveau.runpm parameter is set to 0.
>
> However it seems like -EACCES is indeed returned when runtime power-
> management hasn't been enabled for a device. This is done automatically
> for PCI devices, but not for platform devices. We don't support runtime
> power-management on gk20a yet, therefore pm_runtime_enable() is never
> called, causing disable_depth to remain at -1 and therefore runtime PM
> helpers return -EACCES.
I will fix the commit message, as indeed the -EACCES code is not
directly related to the runpm parameter, but rather to the fact
pm_runtime_enable() is not called for platform devices yet.

Do we however agree on the issue that this patch addresses, and the
way it addresses it?

Thanks,
Alex.