Message-ID: <07040b3e-9137-10ef-9a18-381b0316fef9@suse.de>
Date:   Fri, 3 Apr 2020 09:00:17 +0200
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     Xinliang Liu <xinliang.liu@...aro.org>,
        Tian Tao <tiantao6@...ilicon.com>
Cc:     David Airlie <airlied@...ux.ie>,
        Chen Feng <puck.chen@...ilicon.com>,
        lkml <linux-kernel@...r.kernel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>, linuxarm@...wei.com,
        kraxel@...hat.com, alexander.deucher@....com, tglx@...utronix.de
Subject: Re: [PATCH 2/4] drm/hisilicon: Code cleanup for hibmc_drv_vdac

Hi

Am 03.04.20 um 04:26 schrieb Xinliang Liu:
> Hi Tao,
> 
> On Fri, 6 Mar 2020 at 11:44, Tian Tao <tiantao6@...ilicon.com> wrote:
>>
>> code cleanup for hibmc_drv_vdac.c, no actual function changes.
>>
>> Signed-off-by: Tian Tao <tiantao6@...ilicon.com>
>> Signed-off-by: Gong junjie <gongjunjie2@...wei.com>
>> ---
>>  drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c | 49 ++++++++----------------
>>  1 file changed, 16 insertions(+), 33 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..f0e6bb8 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)
>> @@ -109,13 +83,6 @@ 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");
>> @@ -131,6 +98,22 @@ 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) {
>> +               DRM_ERROR("failed to alloc memory when init connector\n");
>> +               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_register(connector);
> 
> You don't need to register a non-hotplug connector as it will be
> registered at drm_dev_register automatically.
> 
> See function definition:
> 
>  488 /**
>  489  * drm_connector_register - register a connector
>  490  * @connector: the connector to register
>  491  *
>  492  * Register userspace interfaces for a connector. Only call this
> for connectors
>  493  * which can be hotplugged after drm_dev_register() has been
> called already,
>  494  * e.g. DP MST connectors. All other connectors will be
> registered automatically
>  495  * when calling drm_dev_register().
>  496  *
>  497  * Returns:
>  498  * Zero on success, error code on failure.
>  499  */
>  500 int drm_connector_register(struct drm_connector *connector)
>  501 {
> 
> 
> Besides, I don't think this patch cleans much things.

True. Although the auto-kfree of devm_kzalloc() does not work correctly
with DRM and should be replaced.

I'd like to suggest to either allocate the connector as part of struct
hibmc_drm_private, or implement drmm_connector_create() on top of DRM's
new auto-cleanup functionality.

Best regards
Thomas

> 
> -Xinliang
> 
>>         drm_connector_attach_encoder(connector, encoder);
>>
>>         return 0;
>> --
>> 2.7.4
>>
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> dri-devel@...ts.freedesktop.org
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> 

-- 
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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