2021-09-18 18:21:11

by Zhiwei Yang

Subject: [PATCH] drm/radeon: fix uninitialized bool variable

The bool variable detected_hpd_without_ddc in struct radeon_connector
is uninitialized when first used, that may cause unnecessary ddc ops.
Make it as false when a new connector is alloced.

Signed-off-by: Zhiwei Yang <[email protected]>
---
drivers/gpu/drm/radeon/radeon_connectors.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c
index fe12d9d91d7a..c1987a66373f 100644
--- a/drivers/gpu/drm/radeon/radeon_connectors.c
+++ b/drivers/gpu/drm/radeon/radeon_connectors.c
@@ -1866,6 +1866,7 @@ radeon_add_atom_connector(struct drm_device *dev,
bool shared_ddc = false;
bool is_dp_bridge = false;
bool has_aux = false;
+ bool detected_hpd_without_ddc = false;

if (connector_type == DRM_MODE_CONNECTOR_Unknown)
return;
@@ -1923,6 +1924,7 @@ radeon_add_atom_connector(struct drm_device *dev,
radeon_connector->shared_ddc = shared_ddc;
radeon_connector->connector_object_id = connector_object_id;
radeon_connector->hpd = *hpd;
+ radeon_connector->detected_hpd_without_ddc = detected_hpd_without_ddc;

radeon_connector->router = *router;
if (router->ddc_valid || router->cd_valid) {
@@ -2384,6 +2386,7 @@ radeon_add_legacy_connector(struct drm_device *dev,
struct radeon_connector *radeon_connector;
struct i2c_adapter *ddc = NULL;
uint32_t subpixel_order = SubPixelNone;
+ bool detected_hpd_without_ddc = false;

if (connector_type == DRM_MODE_CONNECTOR_Unknown)
return;
@@ -2414,6 +2417,7 @@ radeon_add_legacy_connector(struct drm_device *dev,
radeon_connector->devices = supported_device;
radeon_connector->connector_object_id = connector_object_id;
radeon_connector->hpd = *hpd;
+ radeon_connector->detected_hpd_without_ddc = detected_hpd_without_ddc;

switch (connector_type) {
case DRM_MODE_CONNECTOR_VGA:
--
2.20.1

2021-09-20 09:53:18

by Christian König

Subject: Re: [PATCH] drm/radeon: fix uninitialized bool variable

Am 18.09.21 um 11:41 schrieb Zhiwei Yang:
> The bool variable detected_hpd_without_ddc in struct radeon_connector
> is uninitialized when first used, that may cause unnecessary ddc ops.
> Make it as false when a new connector is alloced.
>
> Signed-off-by: Zhiwei Yang <[email protected]>
> ---
> drivers/gpu/drm/radeon/radeon_connectors.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c
> index fe12d9d91d7a..c1987a66373f 100644
> --- a/drivers/gpu/drm/radeon/radeon_connectors.c
> +++ b/drivers/gpu/drm/radeon/radeon_connectors.c
> @@ -1866,6 +1866,7 @@ radeon_add_atom_connector(struct drm_device *dev,
> bool shared_ddc = false;
> bool is_dp_bridge = false;
> bool has_aux = false;
> + bool detected_hpd_without_ddc = false;

In general good catch, but I don't see the need for a local variable here.

Just initialize the member directly or even better change the allocation
of the connector into a kzalloc().

Christian.

>
> if (connector_type == DRM_MODE_CONNECTOR_Unknown)
> return;
> @@ -1923,6 +1924,7 @@ radeon_add_atom_connector(struct drm_device *dev,
> radeon_connector->shared_ddc = shared_ddc;
> radeon_connector->connector_object_id = connector_object_id;
> radeon_connector->hpd = *hpd;
> + radeon_connector->detected_hpd_without_ddc = detected_hpd_without_ddc;
>
> radeon_connector->router = *router;
> if (router->ddc_valid || router->cd_valid) {
> @@ -2384,6 +2386,7 @@ radeon_add_legacy_connector(struct drm_device *dev,
> struct radeon_connector *radeon_connector;
> struct i2c_adapter *ddc = NULL;
> uint32_t subpixel_order = SubPixelNone;
> + bool detected_hpd_without_ddc = false;
>
> if (connector_type == DRM_MODE_CONNECTOR_Unknown)
> return;
> @@ -2414,6 +2417,7 @@ radeon_add_legacy_connector(struct drm_device *dev,
> radeon_connector->devices = supported_device;
> radeon_connector->connector_object_id = connector_object_id;
> radeon_connector->hpd = *hpd;
> + radeon_connector->detected_hpd_without_ddc = detected_hpd_without_ddc;
>
> switch (connector_type) {
> case DRM_MODE_CONNECTOR_VGA:

2021-09-21 01:38:01

by Alex Deucher

Subject: Re: [PATCH] drm/radeon: fix uninitialized bool variable

On Mon, Sep 20, 2021 at 3:44 AM Christian König
<[email protected]> wrote:
>
>
>
> Am 18.09.21 um 11:41 schrieb Zhiwei Yang:
> > The bool variable detected_hpd_without_ddc in struct radeon_connector
> > is uninitialized when first used, that may cause unnecessary ddc ops.
> > Make it as false when a new connector is alloced.
> >
> > Signed-off-by: Zhiwei Yang <[email protected]>
> > ---
> > drivers/gpu/drm/radeon/radeon_connectors.c | 4 ++++
> > 1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c
> > index fe12d9d91d7a..c1987a66373f 100644
> > --- a/drivers/gpu/drm/radeon/radeon_connectors.c
> > +++ b/drivers/gpu/drm/radeon/radeon_connectors.c
> > @@ -1866,6 +1866,7 @@ radeon_add_atom_connector(struct drm_device *dev,
> > bool shared_ddc = false;
> > bool is_dp_bridge = false;
> > bool has_aux = false;
> > + bool detected_hpd_without_ddc = false;
>
> In general good catch, but I don't see the need for a local variable here.
>
> Just initialize the member directly or even better change the allocation
> of the connector into a kzalloc().

This is already the case:
radeon_connector = kzalloc(sizeof(struct radeon_connector), GFP_KERNEL);
So I don't think this patch is necessary.

Alex

>
> Christian.
>
> >
> > if (connector_type == DRM_MODE_CONNECTOR_Unknown)
> > return;
> > @@ -1923,6 +1924,7 @@ radeon_add_atom_connector(struct drm_device *dev,
> > radeon_connector->shared_ddc = shared_ddc;
> > radeon_connector->connector_object_id = connector_object_id;
> > radeon_connector->hpd = *hpd;
> > + radeon_connector->detected_hpd_without_ddc = detected_hpd_without_ddc;
> >
> > radeon_connector->router = *router;
> > if (router->ddc_valid || router->cd_valid) {
> > @@ -2384,6 +2386,7 @@ radeon_add_legacy_connector(struct drm_device *dev,
> > struct radeon_connector *radeon_connector;
> > struct i2c_adapter *ddc = NULL;
> > uint32_t subpixel_order = SubPixelNone;
> > + bool detected_hpd_without_ddc = false;
> >
> > if (connector_type == DRM_MODE_CONNECTOR_Unknown)
> > return;
> > @@ -2414,6 +2417,7 @@ radeon_add_legacy_connector(struct drm_device *dev,
> > radeon_connector->devices = supported_device;
> > radeon_connector->connector_object_id = connector_object_id;
> > radeon_connector->hpd = *hpd;
> > + radeon_connector->detected_hpd_without_ddc = detected_hpd_without_ddc;
> >
> > switch (connector_type) {
> > case DRM_MODE_CONNECTOR_VGA:
>