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Message-ID: <5093b12f-11e8-0cf0-d9e7-7ec9b52e364d@suse.de>
Date:   Tue, 1 Dec 2020 14:44:06 +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 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;

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,
>>>>>
>>>>
>>>
>>
> 

-- 
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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