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Subject: Re: [PATCH drm/hisilicon v2 1/4] drm/hisilicon: Assgin local variable
 to drm_device
To:     Thomas Zimmermann <tzimmermann@suse.de>,
        Tian Tao <tiantao6@hisilicon.com>, <airlied@linux.ie>,
        <daniel@ffwll.ch>, <kraxel@redhat.com>,
        <alexander.deucher@amd.com>, <tglx@linutronix.de>,
        <dri-devel@lists.freedesktop.org>, <xinliang.liu@linaro.org>,
        <maarten.lankhorst@linux.intel.com>, <mripard@kernel.org>
CC:     <linux-kernel@vger.kernel.org>
References: <1606823754-52451-1-git-send-email-tiantao6@hisilicon.com>
 <1606823754-52451-2-git-send-email-tiantao6@hisilicon.com>
 <fc644426-67db-7128-5f73-8630373ab0e8@suse.de>
 <3f235e08-bb58-be41-8e92-ccd2dfd68b33@huawei.com>
 <389548c9-772c-d86b-700e-032f7d7bde1f@suse.de>
 <51e7e774-6795-8eeb-6701-b1cccc4c6199@huawei.com>
 <5093b12f-11e8-0cf0-d9e7-7ec9b52e364d@suse.de>
From:   "tiantao (H)" <tiantao6@huawei.com>
Message-ID: <9cd5daa7-c934-c834-f2f6-f9b7f7e6b590@huawei.com>
Date:   Wed, 2 Dec 2020 10:06:24 +0800
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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@hisilicon.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.
> 
> 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,
>>>>>>
>>>>>
>>>>
>>>
>>
>