Date:   Wed, 2 Dec 2020 10:54:15 +0800
From:   "tiantao (H)" <tiantao6@...wei.com>
To:     Thomas Zimmermann <tzimmermann@...e.de>,
        Tian Tao <tiantao6@...ilicon.com>, <airlied@...ux.ie>,
        <daniel@...ll.ch>, <kraxel@...hat.com>,
        <alexander.deucher@....com>, <tglx@...utronix.de>,
        <dri-devel@...ts.freedesktop.org>, <xinliang.liu@...aro.org>,
        <maarten.lankhorst@...ux.intel.com>, <mripard@...nel.org>
CC:     <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH drm/hisilicon v2 1/4] drm/hisilicon: Assgin local variable
 to drm_device



在 2020/12/2 10:06, tiantao (H) 写道:
> 
> 
> 在 2020/12/1 21:44, Thomas Zimmermann 写道:
>> Hi
>>
>> Am 01.12.20 um 14:05 schrieb tiantao (H):
>>>
>>>
>>> 在 2020/12/1 20:36, Thomas Zimmermann 写道:
>>>> Hi
>>>>
>>>> Am 01.12.20 um 13:26 schrieb tiantao (H):
>>>>>
>>>>>
>>>>> 在 2020/12/1 20:17, Thomas Zimmermann 写道:
>>>>>> Hi
>>>>>>
>>>>>> Am 01.12.20 um 12:55 schrieb Tian Tao:
>>>>>>> Assign local variable to struct drm_device *dev because they are
>>>>>>> used multiple times within a function.
>>>>>>>
>>>>>>> Signed-off-by: Tian Tao <tiantao6@...ilicon.com>
>>>>>>> ---
>>>>>>>   drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_de.c   |  2 +-
>>>>>>>   drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c  | 30 
>>>>>>> ++++++++++++------------
>>>>>>>   drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h  |  2 +-
>>>>>>>   drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c |  2 +-
>>>>>>>   drivers/gpu/drm/hisilicon/hibmc/hibmc_ttm.c      |  8 ++++---
>>>>>>>   5 files changed, 23 insertions(+), 21 deletions(-)
>>>>>>>
>>>>>>> diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_de.c 
>>>>>>> b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_de.c
>>>>>>> index ea962ac..096eea9 100644
>>>>>>> --- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_de.c
>>>>>>> +++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_de.c
>>>>>>> @@ -499,7 +499,7 @@ static const struct drm_crtc_helper_funcs 
>>>>>>> hibmc_crtc_helper_funcs = {
>>>>>>>   int hibmc_de_init(struct hibmc_drm_private *priv)
>>>>>>>   {
>>>>>>> -    struct drm_device *dev = priv->dev;
>>>>>>> +    struct drm_device *dev = &priv->dev;
>>>>>>>       struct drm_crtc *crtc = &priv->crtc;
>>>>>>>       struct drm_plane *plane = &priv->primary_plane;
>>>>>>>       int ret;
>>>>>>> diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c 
>>>>>>> b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
>>>>>>> index d845657..dd9fadc 100644
>>>>>>> --- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
>>>>>>> +++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
>>>>>>> @@ -79,31 +79,32 @@ static const struct dev_pm_ops hibmc_pm_ops = {
>>>>>>>   static int hibmc_kms_init(struct hibmc_drm_private *priv)
>>>>>>>   {
>>>>>>> +    struct drm_device *dev = &priv->dev;
>>>>>>>       int ret;
>>>>>>> -    drm_mode_config_init(priv->dev);
>>>>>>> +    drm_mode_config_init(dev);
>>>>>>>       priv->mode_config_initialized = true;
>>>>>>> -    priv->dev->mode_config.min_width = 0;
>>>>>>> -    priv->dev->mode_config.min_height = 0;
>>>>>>> -    priv->dev->mode_config.max_width = 1920;
>>>>>>> -    priv->dev->mode_config.max_height = 1200;
>>>>>>> +    dev->mode_config.min_width = 0;
>>>>>>> +    dev->mode_config.min_height = 0;
>>>>>>> +    dev->mode_config.max_width = 1920;
>>>>>>> +    dev->mode_config.max_height = 1200;
>>>>>>> -    priv->dev->mode_config.fb_base = priv->fb_base;
>>>>>>> -    priv->dev->mode_config.preferred_depth = 32;
>>>>>>> -    priv->dev->mode_config.prefer_shadow = 1;
>>>>>>> +    dev->mode_config.fb_base = priv->fb_base;
>>>>>>> +    dev->mode_config.preferred_depth = 32;
>>>>>>> +    dev->mode_config.prefer_shadow = 1;
>>>>>>> -    priv->dev->mode_config.funcs = (void *)&hibmc_mode_funcs;
>>>>>>> +    dev->mode_config.funcs = (void *)&hibmc_mode_funcs;
>>>>>>>       ret = hibmc_de_init(priv);
>>>>>>>       if (ret) {
>>>>>>> -        drm_err(priv->dev, "failed to init de: %d\n", ret);
>>>>>>> +        drm_err(dev, "failed to init de: %d\n", ret);
>>>>>>>           return ret;
>>>>>>>       }
>>>>>>>       ret = hibmc_vdac_init(priv);
>>>>>>>       if (ret) {
>>>>>>> -        drm_err(priv->dev, "failed to init vdac: %d\n", ret);
>>>>>>> +        drm_err(dev, "failed to init vdac: %d\n", ret);
>>>>>>>           return ret;
>>>>>>>       }
>>>>>>> @@ -113,7 +114,7 @@ static int hibmc_kms_init(struct 
>>>>>>> hibmc_drm_private *priv)
>>>>>>>   static void hibmc_kms_fini(struct hibmc_drm_private *priv)
>>>>>>>   {
>>>>>>>       if (priv->mode_config_initialized) {
>>>>>>> -        drm_mode_config_cleanup(priv->dev);
>>>>>>> +        drm_mode_config_cleanup(&priv->dev);
>>>>>>>           priv->mode_config_initialized = false;
>>>>>>>       }
>>>>>>>   }
>>>>>>> @@ -202,7 +203,7 @@ static void hibmc_hw_config(struct 
>>>>>>> hibmc_drm_private *priv)
>>>>>>>   static int hibmc_hw_map(struct hibmc_drm_private *priv)
>>>>>>>   {
>>>>>>> -    struct drm_device *dev = priv->dev;
>>>>>>> +    struct drm_device *dev = &priv->dev;
>>>>>>>       struct pci_dev *pdev = dev->pdev;
>>>>>>>       resource_size_t addr, size, ioaddr, iosize;
>>>>>>> @@ -258,7 +259,7 @@ static int hibmc_unload(struct drm_device *dev)
>>>>>>>   static int hibmc_load(struct drm_device *dev)
>>>>>>>   {
>>>>>>> -    struct hibmc_drm_private *priv;
>>>>>>> +    struct hibmc_drm_private *priv = to_hibmc_drm_private(dev);
>>>>>>>       int ret;
>>>>>>>       priv = drmm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>>>>>>> @@ -267,7 +268,6 @@ static int hibmc_load(struct drm_device *dev)
>>>>>>>           return -ENOMEM;
>>>>>>>       }
>>>>>>>       dev->dev_private = priv;
>>>>>>> -    priv->dev = dev;
>>>>>>
>>>>>> I'm sure this either does not build or does not work. There's a 
>>>>>> call to drm_dev_alloc(), which initialized the DRM device. You 
>>>>>> need to assign the returned device here. The embedding of dev only 
>>>>>> work after you switched to devm_drm_dev_alloc() in the next patch.
>>>>>>
>>>>>> For the patch at hand, just keep struct hibmc_drm_private.dev as a 
>>>>>> pointer and you should be fine.
>>>>>>
>>>>> Changing drm_device *dev to drm_device dev and using 
>>>>> devm_drm_dev_alloc does not easily split into two patches.
>>>>> The patch does not compile well on its own, but it will compile 
>>>>> fine with patch #2.
>>>>> Can patch #1 and patch #2 be combined into a single patch,just like 
>>>>> V1.
>>>>
>>>> Most of the code in this patch does
>>>>
>>>>    struct drm_device *dev = &priv->dev;
>>>>
>>>> to get dev as a local variable. Why don't you do
>>>>
>>>>    struct drm_device *dev = priv->dev;
>>>>
>>>> ?
>>>>
>>>> That's all that's really needed.
>>>
>>> +    priv = devm_drm_dev_alloc(&pdev->dev, &hibmc_driver,
>>> +                  struct hibmc_drm_private, dev);
>>> devm_drm_dev_alloc function requires parameter 4, dev must be a 
>>> non-pointer for it to work. so had to change dev in the 
>>> hibmc_drm_private  to non-pointer.
>>> This is also the reason to change drm_device *dev to drm_device dev.
>>
>> Yes, but that's what patch 2 is about. Patch 1 is about simplifying 
>> these pointer dereferences into local variables. For this, all you 
>> need is
>>
>>      struct drm_device *dev = priv->dev;
> I'm sorry, I still don't understand what you mean.The latest code on the 
> drm branch looks like this "struct drm_device *dev = priv->dev;"
> If I change the dev of hibmc_drm_private to local variables, I won't be 
> able to assign it like this "struct drm_device *dev = priv->dev;", right?
>>
>> In patch 2, these lines are then changed to
>>
>>      struct drm_device *dev = &priv->dev;
>>
>> That makes 2 self-contained patches.
patch #1
first changed drm_device *dev to drm_device dev
then
  drm = &priv->dev;
  err = drm_dev_init(drm, &hibmc_drm_private , &pdev->dev);
patch #2

using devm_drm_dev_alloc()

Is this right ?

>>
>> Best regards
>> Thomas
>>
>>>>
>>>> Best regards
>>>> Thomas
>>>>
>>>>>> Best regards
>>>>>> Thomas
>>>>>>
>>>>>>>       ret = hibmc_hw_init(priv);
>>>>>>>       if (ret)
>>>>>>> diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h 
>>>>>>> b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h
>>>>>>> index f310a83..e35353a 100644
>>>>>>> --- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h
>>>>>>> +++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h
>>>>>>> @@ -37,7 +37,7 @@ struct hibmc_drm_private {
>>>>>>>       resource_size_t  fb_size;
>>>>>>>       /* drm */
>>>>>>> -    struct drm_device  *dev;
>>>>>>> +    struct drm_device dev;
>>>>>>>       struct drm_plane primary_plane;
>>>>>>>       struct drm_crtc crtc;
>>>>>>>       struct drm_encoder encoder;
>>>>>>> diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c 
>>>>>>> b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c
>>>>>>> index 74e26c2..d35548d 100644
>>>>>>> --- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c
>>>>>>> +++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c
>>>>>>> @@ -96,7 +96,7 @@ static const struct drm_encoder_funcs 
>>>>>>> hibmc_encoder_funcs = {
>>>>>>>   int hibmc_vdac_init(struct hibmc_drm_private *priv)
>>>>>>>   {
>>>>>>> -    struct drm_device *dev = priv->dev;
>>>>>>> +    struct drm_device *dev = &priv->dev;
>>>>>>>       struct hibmc_connector *hibmc_connector = &priv->connector;
>>>>>>>       struct drm_encoder *encoder = &priv->encoder;
>>>>>>>       struct drm_connector *connector = &hibmc_connector->base;
>>>>>>> diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_ttm.c 
>>>>>>> b/drivers/gpu/drm/hisilicon/hibmc/hibmc_ttm.c
>>>>>>> index 602ece1..e84fb81 100644
>>>>>>> --- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_ttm.c
>>>>>>> +++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_ttm.c
>>>>>>> @@ -25,7 +25,7 @@ int hibmc_mm_init(struct hibmc_drm_private *hibmc)
>>>>>>>   {
>>>>>>>       struct drm_vram_mm *vmm;
>>>>>>>       int ret;
>>>>>>> -    struct drm_device *dev = hibmc->dev;
>>>>>>> +    struct drm_device *dev = &hibmc->dev;
>>>>>>>       vmm = drm_vram_helper_alloc_mm(dev,
>>>>>>>                          pci_resource_start(dev->pdev, 0),
>>>>>>> @@ -41,10 +41,12 @@ int hibmc_mm_init(struct hibmc_drm_private 
>>>>>>> *hibmc)
>>>>>>>   void hibmc_mm_fini(struct hibmc_drm_private *hibmc)
>>>>>>>   {
>>>>>>> -    if (!hibmc->dev->vram_mm)
>>>>>>> +    struct drm_device *dev = &hibmc->dev;
>>>>>>> +
>>>>>>> +    if (!dev->vram_mm)
>>>>>>>           return;
>>>>>>> -    drm_vram_helper_release_mm(hibmc->dev);
>>>>>>> +    drm_vram_helper_release_mm(dev);
>>>>>>>   }
>>>>>>>   int hibmc_dumb_create(struct drm_file *file, struct drm_device 
>>>>>>> *dev,
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
> 
> 
> .
> 

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