Message-ID: <6ce6f2b4-4541-a8a4-7081-ac52106d238e@suse.de>
Date:   Wed, 2 Dec 2020 08:49:09 +0100
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     "tiantao (H)" <tiantao6@...wei.com>,
        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

Hi

Am 02.12.20 um 03:54 schrieb tiantao (H):
> 
> 
> 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 ?

Oh, I guess I now see why we're misunderstanding each other. By local 
variable, I mean that dev is a local pointer in a function. I didn't 
mean that the actual instance of dev is stored in struct 
hibmc_drm_private. In patch 1 it's still supposed to be a pointer in 
struct hibmc_drm_private. Only patch 2 will make dev an instance.

Anyway, before this goes on forever, maybe just merge patches 1 and 2 
and resubmit.

Best regards
Thomas

> 
>>>
>>> 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,
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>>
>> .
>>
> 

-- 
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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