2020-04-11 06:28:46

by Tian Tao

[permalink] [raw]
Subject: [PATCH v2] drm/hisilicon: Code refactoring for hibmc_drv_vdac

code refactoring for hibmc_drv_vdac.c, no actual function changes.

v2:
remove the debug message.

Signed-off-by: Tian Tao <[email protected]>
Reviewed-by: Joe Perches <[email protected]>
---
drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c | 50 +++++++-----------------
1 file changed, 14 insertions(+), 36 deletions(-)

diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c
index 678ac2e..077b7996 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c
+++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c
@@ -52,32 +52,6 @@ static const struct drm_connector_funcs hibmc_connector_funcs = {
.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
};

-static struct drm_connector *
-hibmc_connector_init(struct hibmc_drm_private *priv)
-{
- struct drm_device *dev = priv->dev;
- struct drm_connector *connector;
- int ret;
-
- connector = devm_kzalloc(dev->dev, sizeof(*connector), GFP_KERNEL);
- if (!connector) {
- DRM_ERROR("failed to alloc memory when init connector\n");
- return ERR_PTR(-ENOMEM);
- }
-
- ret = drm_connector_init(dev, connector,
- &hibmc_connector_funcs,
- DRM_MODE_CONNECTOR_VGA);
- if (ret) {
- DRM_ERROR("failed to init connector: %d\n", ret);
- return ERR_PTR(ret);
- }
- drm_connector_helper_add(connector,
- &hibmc_connector_helper_funcs);
-
- return connector;
-}
-
static void hibmc_encoder_mode_set(struct drm_encoder *encoder,
struct drm_display_mode *mode,
struct drm_display_mode *adj_mode)
@@ -109,18 +83,9 @@ int hibmc_vdac_init(struct hibmc_drm_private *priv)
struct drm_connector *connector;
int ret;

- connector = hibmc_connector_init(priv);
- if (IS_ERR(connector)) {
- DRM_ERROR("failed to create connector: %ld\n",
- PTR_ERR(connector));
- return PTR_ERR(connector);
- }
-
encoder = devm_kzalloc(dev->dev, sizeof(*encoder), GFP_KERNEL);
- if (!encoder) {
- DRM_ERROR("failed to alloc memory when init encoder\n");
+ if (!encoder)
return -ENOMEM;
- }

encoder->possible_crtcs = 0x1;
ret = drm_encoder_init(dev, encoder, &hibmc_encoder_funcs,
@@ -131,6 +96,19 @@ int hibmc_vdac_init(struct hibmc_drm_private *priv)
}

drm_encoder_helper_add(encoder, &hibmc_encoder_helper_funcs);
+
+ connector = devm_kzalloc(dev->dev, sizeof(*connector), GFP_KERNEL);
+ if (!connector)
+ return -ENOMEM;
+
+ ret = drm_connector_init(dev, connector, &hibmc_connector_funcs,
+ DRM_MODE_CONNECTOR_VGA);
+ if (ret) {
+ DRM_ERROR("failed to init connector: %d\n", ret);
+ return ret;
+ }
+ drm_connector_helper_add(connector, &hibmc_connector_helper_funcs);
+
drm_connector_attach_encoder(connector, encoder);

return 0;
--
2.7.4


2020-06-18 13:55:48

by Thomas Zimmermann

[permalink] [raw]
Subject: Re: [PATCH v2] drm/hisilicon: Code refactoring for hibmc_drv_vdac

Hi,

sorry for letting these patches sit around for so long. I'd say that if
you waited for a week or two without further responses, it's ok to ping
people.

Am 11.04.20 um 08:25 schrieb Tian Tao:
> code refactoring for hibmc_drv_vdac.c, no actual function changes.
>
> v2:
> remove the debug message.
>
> Signed-off-by: Tian Tao <[email protected]>
> Reviewed-by: Joe Perches <[email protected]>
> ---
> drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c | 50 +++++++-----------------
> 1 file changed, 14 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c
> index 678ac2e..077b7996 100644
> --- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c
> +++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c
> @@ -52,32 +52,6 @@ static const struct drm_connector_funcs hibmc_connector_funcs = {
> .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
> };
>
> -static struct drm_connector *
> -hibmc_connector_init(struct hibmc_drm_private *priv)
> -{
> - struct drm_device *dev = priv->dev;
> - struct drm_connector *connector;
> - int ret;
> -
> - connector = devm_kzalloc(dev->dev, sizeof(*connector), GFP_KERNEL);
> - if (!connector) {
> - DRM_ERROR("failed to alloc memory when init connector\n");
> - return ERR_PTR(-ENOMEM);
> - }
> -
> - ret = drm_connector_init(dev, connector,
> - &hibmc_connector_funcs,
> - DRM_MODE_CONNECTOR_VGA);
> - if (ret) {
> - DRM_ERROR("failed to init connector: %d\n", ret);
> - return ERR_PTR(ret);
> - }
> - drm_connector_helper_add(connector,
> - &hibmc_connector_helper_funcs);
> -
> - return connector;
> -}
> -
> static void hibmc_encoder_mode_set(struct drm_encoder *encoder,
> struct drm_display_mode *mode,
> struct drm_display_mode *adj_mode)
> @@ -109,18 +83,9 @@ int hibmc_vdac_init(struct hibmc_drm_private *priv)
> struct drm_connector *connector;
> int ret;
>
> - connector = hibmc_connector_init(priv);
> - if (IS_ERR(connector)) {
> - DRM_ERROR("failed to create connector: %ld\n",
> - PTR_ERR(connector));
> - return PTR_ERR(connector);
> - }
> -
> encoder = devm_kzalloc(dev->dev, sizeof(*encoder), GFP_KERNEL);
> - if (!encoder) {
> - DRM_ERROR("failed to alloc memory when init encoder\n");
> + if (!encoder)
> return -ENOMEM;
> - }
>
> encoder->possible_crtcs = 0x1;
> ret = drm_encoder_init(dev, encoder, &hibmc_encoder_funcs,
> @@ -131,6 +96,19 @@ int hibmc_vdac_init(struct hibmc_drm_private *priv)
> }
>
> drm_encoder_helper_add(encoder, &hibmc_encoder_helper_funcs);
> +
> + connector = devm_kzalloc(dev->dev, sizeof(*connector), GFP_KERNEL);

Overall, the patch seems correct, expect for this line. DRM data
structures should now be allocated with drmm_kzalloc() in drm_managed.h.
It was added recently.

With devm_kzalloc(), the memory will be released when the HW device goes
away. If userspace still holds a reference, the driver can segfault.
Using drmm_kzalloc() delays the release until the memory is really unused.

However, hibmc's modesetting pipeline appears to be always the same. I
think you should consider embedding connector and encoder (and crtc) in
struct hibmc_drm_private. Would make the code simpler and more robust.

Best regards
Thomas



> + if (!connector)
> + return -ENOMEM;
> +
> + ret = drm_connector_init(dev, connector, &hibmc_connector_funcs,
> + DRM_MODE_CONNECTOR_VGA);
> + if (ret) {
> + DRM_ERROR("failed to init connector: %d\n", ret);
> + return ret;
> + }
> + drm_connector_helper_add(connector, &hibmc_connector_helper_funcs);
> +
> drm_connector_attach_encoder(connector, encoder);
>
> return 0;
>

--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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