[PATCH 3/5] drm/udl: Add GEM object functions for free(), vmap(), and vunmap()

[Thomas Zimmermann]

Hi

Am 25.10.19 um 09:40 schrieb Daniel Vetter:
> On Thu, Oct 24, 2019 at 04:42:35PM +0200, Thomas Zimmermann wrote:
>> Implementing vmap() and vunmap() of struct drm_gem_object_funcs is
>> required by generic fbdev emulation. Supporting free() is easy as
>> well. More udl-specific interfaces can probably be replaced by GEM
>> object functions in later patches.
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
>> ---
>>  drivers/gpu/drm/udl/udl_gem.c | 34 ++++++++++++++++++++++++++++++++++
>>  1 file changed, 34 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/udl/udl_gem.c b/drivers/gpu/drm/udl/udl_gem.c
>> index 3ea0cd9ae2d6..6ca097c270d6 100644
>> --- a/drivers/gpu/drm/udl/udl_gem.c
>> +++ b/drivers/gpu/drm/udl/udl_gem.c
>> @@ -11,6 +11,8 @@
>>  
>>  #include "udl_drv.h"
>>  
>> +static const struct drm_gem_object_funcs udl_gem_object_funcs;
>> +
>>  struct udl_gem_object *udl_gem_alloc_object(struct drm_device *dev,
>>  					    size_t size)
>>  {
>> @@ -25,6 +27,7 @@ struct udl_gem_object *udl_gem_alloc_object(struct drm_device *dev,
>>  		return NULL;
>>  	}
>>  
>> +	obj->base.funcs = &udl_gem_object_funcs;
>>  	obj->flags = UDL_BO_CACHEABLE;
>>  	return obj;
>>  }
>> @@ -230,3 +233,34 @@ int udl_gem_mmap(struct drm_file *file, struct drm_device *dev,
>>  	mutex_unlock(&udl->gem_lock);
>>  	return ret;
>>  }
>> +
>> +/*
>> + * Helpers for struct drm_gem_object_funcs
>> + */
>> +
>> +static void udl_gem_object_free(struct drm_gem_object *obj)
>> +{
>> +	udl_gem_free_object(obj);
>> +}
>> +
>> +static void *udl_gem_object_vmap(struct drm_gem_object *obj)
>> +{
>> +	struct udl_gem_object *uobj = to_udl_bo(obj);
>> +	int ret;
>> +
>> +	ret = udl_gem_vmap(uobj);
>> +	if (ret)
>> +		return ERR_PTR(ret);
>> +	return uobj->vmapping;
>> +}
>> +
>> +static void udl_gem_object_vunmap(struct drm_gem_object *obj, void *vaddr)
>> +{
>> +	return udl_gem_vunmap(to_udl_bo(obj));
>> +}
>> +
>> +static const struct drm_gem_object_funcs udl_gem_object_funcs = {
>> +	.free	= udl_gem_object_free,
>> +	.vmap	= udl_gem_object_vmap,
>> +	.vunmap	= udl_gem_object_vunmap,
> 
> Yeah this doesn't work, you need to refcount the vmap here I think. I'd

I see. Should have thought of that...

> say simpler to first cut over to shmem helpers.

Right. I was already attempting the conversion and the udl gem is more
or less the same as shmem, except for the flags field. [1] The flag
signals page attributes for mmap-ing [2]. For prime-imported BOs its is
set to writecombining, and for local BOs it is set to cached. Shmem
always maps with writecombining.

I don't see why udl BOs are special wrt to mmap-ing. It seems to be some
kind of optimization. Do you have an idea?

Best regards
Thomas

[1]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/udl/udl_drv.h?h=v5.3#n78
[2]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/udl/udl_gem.c?h=v5.3#n57

> -Daniel
> 

-- 
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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