[RESEND PATCH 4/5] drm: Add a drm_drv_enabled() helper function

[RESEND PATCH 4/5] drm: Add a drm_drv_enabled() helper function

[Javier Martinez Canillas]

DRM drivers can use this to determine whether they can be enabled or not.

For now it's just a wrapper around drm_modeset_disabled() but having the
indirection level will allow to add other conditions besides "nomodeset".

Suggested-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
---

 drivers/gpu/drm/drm_drv.c | 21 +++++++++++++++++++++
 include/drm/drm_drv.h     |  1 +
 2 files changed, 22 insertions(+)

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 8214a0b1ab7f..70ef08941e06 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -975,6 +975,27 @@ int drm_dev_set_unique(struct drm_device *dev, const char *name)
 }
 EXPORT_SYMBOL(drm_dev_set_unique);
 
+/**
+ * drm_drv_enabled - Checks if a DRM driver can be enabled
+ * @driver: DRM driver to check
+ *
+ * Checks whether a DRM driver can be enabled or not. This may be the case
+ * if the "nomodeset" kernel command line parameter is used.
+ *
+ * Returns:
+ * True if the DRM driver is enabled and false otherwise.
+ */
+bool drm_drv_enabled(const struct drm_driver *driver)
+{
+	if (drm_modeset_disabled()) {
+		DRM_INFO("%s driver is disabled\n", driver->name);
+		return false;
+	}
+
+	return true;
+}
+EXPORT_SYMBOL(drm_drv_enabled);
+
 /*
  * DRM Core
  * The DRM core module initializes all global DRM objects and makes them
diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
index 0cd95953cdf5..48f2b6eec012 100644
--- a/include/drm/drm_drv.h
+++ b/include/drm/drm_drv.h
@@ -598,5 +598,6 @@ static inline bool drm_drv_uses_atomic_modeset(struct drm_device *dev)
 
 int drm_dev_set_unique(struct drm_device *dev, const char *name);
 
+bool drm_drv_enabled(const struct drm_driver *driver);
 
 #endif
-- 
2.33.1

Re: [RESEND PATCH 4/5] drm: Add a drm_drv_enabled() helper function

[Jani Nikula]

On Wed, 03 Nov 2021, Javier Martinez Canillas <javierm@redhat.com> wrote:
> DRM drivers can use this to determine whether they can be enabled or not.
>
> For now it's just a wrapper around drm_modeset_disabled() but having the
> indirection level will allow to add other conditions besides "nomodeset".
>
> Suggested-by: Thomas Zimmermann <tzimmermann@suse.de>
> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>

Can't see i915 trivially using this due to the drm_driver
parameter. Please let's not merge helpers like this without actual
users.

BR,
Jani.


> ---
>
>  drivers/gpu/drm/drm_drv.c | 21 +++++++++++++++++++++
>  include/drm/drm_drv.h     |  1 +
>  2 files changed, 22 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> index 8214a0b1ab7f..70ef08941e06 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -975,6 +975,27 @@ int drm_dev_set_unique(struct drm_device *dev, const char *name)
>  }
>  EXPORT_SYMBOL(drm_dev_set_unique);
>  
> +/**
> + * drm_drv_enabled - Checks if a DRM driver can be enabled
> + * @driver: DRM driver to check
> + *
> + * Checks whether a DRM driver can be enabled or not. This may be the case
> + * if the "nomodeset" kernel command line parameter is used.
> + *
> + * Returns:
> + * True if the DRM driver is enabled and false otherwise.
> + */
> +bool drm_drv_enabled(const struct drm_driver *driver)
> +{
> +	if (drm_modeset_disabled()) {
> +		DRM_INFO("%s driver is disabled\n", driver->name);
> +		return false;
> +	}
> +
> +	return true;
> +}
> +EXPORT_SYMBOL(drm_drv_enabled);
> +
>  /*
>   * DRM Core
>   * The DRM core module initializes all global DRM objects and makes them
> diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
> index 0cd95953cdf5..48f2b6eec012 100644
> --- a/include/drm/drm_drv.h
> +++ b/include/drm/drm_drv.h
> @@ -598,5 +598,6 @@ static inline bool drm_drv_uses_atomic_modeset(struct drm_device *dev)
>  
>  int drm_dev_set_unique(struct drm_device *dev, const char *name);
>  
> +bool drm_drv_enabled(const struct drm_driver *driver);
>  
>  #endif

-- 
Jani Nikula, Intel Open Source Graphics Center

Re: [RESEND PATCH 4/5] drm: Add a drm_drv_enabled() helper function

[Thomas Zimmermann]

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Hi

Am 03.11.21 um 14:41 schrieb Jani Nikula:
> On Wed, 03 Nov 2021, Javier Martinez Canillas <javierm@redhat.com> wrote:
>> DRM drivers can use this to determine whether they can be enabled or not.
>>
>> For now it's just a wrapper around drm_modeset_disabled() but having the
>> indirection level will allow to add other conditions besides "nomodeset".
>>
>> Suggested-by: Thomas Zimmermann <tzimmermann@suse.de>
>> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
> 
> Can't see i915 trivially using this due to the drm_driver
> parameter. Please let's not merge helpers like this without actual
> users.

Can you explain?

This would be called on the top of the PCI probe function. The parameter 
would allow to decide on a per-driver base (e.g., to ignore generic 
drivers).

Best regards
Thomas

> 
> BR,
> Jani.
> 
> 
>> ---
>>
>>   drivers/gpu/drm/drm_drv.c | 21 +++++++++++++++++++++
>>   include/drm/drm_drv.h     |  1 +
>>   2 files changed, 22 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
>> index 8214a0b1ab7f..70ef08941e06 100644
>> --- a/drivers/gpu/drm/drm_drv.c
>> +++ b/drivers/gpu/drm/drm_drv.c
>> @@ -975,6 +975,27 @@ int drm_dev_set_unique(struct drm_device *dev, const char *name)
>>   }
>>   EXPORT_SYMBOL(drm_dev_set_unique);
>>   
>> +/**
>> + * drm_drv_enabled - Checks if a DRM driver can be enabled
>> + * @driver: DRM driver to check
>> + *
>> + * Checks whether a DRM driver can be enabled or not. This may be the case
>> + * if the "nomodeset" kernel command line parameter is used.
>> + *
>> + * Returns:
>> + * True if the DRM driver is enabled and false otherwise.
>> + */
>> +bool drm_drv_enabled(const struct drm_driver *driver)
>> +{
>> +	if (drm_modeset_disabled()) {
>> +		DRM_INFO("%s driver is disabled\n", driver->name);
>> +		return false;
>> +	}
>> +
>> +	return true;
>> +}
>> +EXPORT_SYMBOL(drm_drv_enabled);
>> +
>>   /*
>>    * DRM Core
>>    * The DRM core module initializes all global DRM objects and makes them
>> diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
>> index 0cd95953cdf5..48f2b6eec012 100644
>> --- a/include/drm/drm_drv.h
>> +++ b/include/drm/drm_drv.h
>> @@ -598,5 +598,6 @@ static inline bool drm_drv_uses_atomic_modeset(struct drm_device *dev)
>>   
>>   int drm_dev_set_unique(struct drm_device *dev, const char *name);
>>   
>> +bool drm_drv_enabled(const struct drm_driver *driver);
>>   
>>   #endif
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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Re: [RESEND PATCH 4/5] drm: Add a drm_drv_enabled() helper function

[Jani Nikula]

On Wed, 03 Nov 2021, Thomas Zimmermann <tzimmermann@suse.de> wrote:
> Hi
>
> Am 03.11.21 um 14:41 schrieb Jani Nikula:
>> On Wed, 03 Nov 2021, Javier Martinez Canillas <javierm@redhat.com> wrote:
>>> DRM drivers can use this to determine whether they can be enabled or not.
>>>
>>> For now it's just a wrapper around drm_modeset_disabled() but having the
>>> indirection level will allow to add other conditions besides "nomodeset".
>>>
>>> Suggested-by: Thomas Zimmermann <tzimmermann@suse.de>
>>> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
>> 
>> Can't see i915 trivially using this due to the drm_driver
>> parameter. Please let's not merge helpers like this without actual
>> users.
>
> Can you explain?
>
> This would be called on the top of the PCI probe function. The parameter 
> would allow to decide on a per-driver base (e.g., to ignore generic 
> drivers).

Where and how exactly? This is why we need to see the patch using the
function. A patch is worth a thousand words. ;)

See current vgacon_text_force() usage in i915/i915_module.c. It happens
way before anything related to pci or drm driver. Why bother with the
complicated setup and teardown of stuff if you can bail out earlier?


BR,
Jani.

>
> Best regards
> Thomas
>
>> 
>> BR,
>> Jani.
>> 
>> 
>>> ---
>>>
>>>   drivers/gpu/drm/drm_drv.c | 21 +++++++++++++++++++++
>>>   include/drm/drm_drv.h     |  1 +
>>>   2 files changed, 22 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
>>> index 8214a0b1ab7f..70ef08941e06 100644
>>> --- a/drivers/gpu/drm/drm_drv.c
>>> +++ b/drivers/gpu/drm/drm_drv.c
>>> @@ -975,6 +975,27 @@ int drm_dev_set_unique(struct drm_device *dev, const char *name)
>>>   }
>>>   EXPORT_SYMBOL(drm_dev_set_unique);
>>>   
>>> +/**
>>> + * drm_drv_enabled - Checks if a DRM driver can be enabled
>>> + * @driver: DRM driver to check
>>> + *
>>> + * Checks whether a DRM driver can be enabled or not. This may be the case
>>> + * if the "nomodeset" kernel command line parameter is used.
>>> + *
>>> + * Returns:
>>> + * True if the DRM driver is enabled and false otherwise.
>>> + */
>>> +bool drm_drv_enabled(const struct drm_driver *driver)
>>> +{
>>> +	if (drm_modeset_disabled()) {
>>> +		DRM_INFO("%s driver is disabled\n", driver->name);
>>> +		return false;
>>> +	}
>>> +
>>> +	return true;
>>> +}
>>> +EXPORT_SYMBOL(drm_drv_enabled);
>>> +
>>>   /*
>>>    * DRM Core
>>>    * The DRM core module initializes all global DRM objects and makes them
>>> diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
>>> index 0cd95953cdf5..48f2b6eec012 100644
>>> --- a/include/drm/drm_drv.h
>>> +++ b/include/drm/drm_drv.h
>>> @@ -598,5 +598,6 @@ static inline bool drm_drv_uses_atomic_modeset(struct drm_device *dev)
>>>   
>>>   int drm_dev_set_unique(struct drm_device *dev, const char *name);
>>>   
>>> +bool drm_drv_enabled(const struct drm_driver *driver);
>>>   
>>>   #endif
>> 

-- 
Jani Nikula, Intel Open Source Graphics Center

Re: [RESEND PATCH 4/5] drm: Add a drm_drv_enabled() helper function

[Javier Martinez Canillas]

Hello Jani,

On 11/4/21 12:10, Jani Nikula wrote:
> On Wed, 03 Nov 2021, Thomas Zimmermann <tzimmermann@suse.de> wrote:
>> Hi
>>
>> Am 03.11.21 um 14:41 schrieb Jani Nikula:
>>> On Wed, 03 Nov 2021, Javier Martinez Canillas <javierm@redhat.com> wrote:
>>>> DRM drivers can use this to determine whether they can be enabled or not.
>>>>
>>>> For now it's just a wrapper around drm_modeset_disabled() but having the
>>>> indirection level will allow to add other conditions besides "nomodeset".
>>>>
>>>> Suggested-by: Thomas Zimmermann <tzimmermann@suse.de>
>>>> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
>>>
>>> Can't see i915 trivially using this due to the drm_driver
>>> parameter. Please let's not merge helpers like this without actual
>>> users.
>>
>> Can you explain?
>>
>> This would be called on the top of the PCI probe function. The parameter 
>> would allow to decide on a per-driver base (e.g., to ignore generic 
>> drivers).
> 
> Where and how exactly? This is why we need to see the patch using the
> function. A patch is worth a thousand words. ;)
>

Thomas suggested to squash patches #4 and #5 so I'll do that when posting v2.
 
> See current vgacon_text_force() usage in i915/i915_module.c. It happens
> way before anything related to pci or drm driver. Why bother with the
> complicated setup and teardown of stuff if you can bail out earlier?
>

Yes, most drivers use vgacon_text_force() in their module init callback.

The ones that do in their probe function are drivers that don't have a
module init/exit but just use the module_platform_driver() macro.

I won't modify that and will keep the bail in the same place that the
drivers already do. I hope to have time and post a new revision today.

> 
> BR,
> Jani.
> 
Best regards,
-- 
Javier Martinez Canillas
Linux Engineering
Red Hat