Re: [Intel-gfx] [PATCH 1/3] drm/i915: Set I915_BO_ALLOC_USER for framebuffer

["Das, Nirmoy" <nirmoy.das@intel.com>]

On 3/6/2023 6:30 PM, Ville Syrjälä wrote:
> On Mon, Mar 06, 2023 at 05:22:19PM +0100, Das, Nirmoy wrote:
>> On 3/6/2023 3:21 PM, Ville Syrjälä wrote:
>>> On Mon, Mar 06, 2023 at 11:28:48AM +0100, Nirmoy Das wrote:
>>>> Framebuffer is exposed to userspace so set I915_BO_ALLOC_USER
>>>> flag for it. This also make sure that ttm allocates offset
>>>> for lmem objects.
>>> I have no idea what that means.
>> Sorry for poor explanation.
>>
>> Without I915_BO_ALLOC_USER, ttm will assume the obj as kernel buffer and
>> will not allocate fake offset which I needed for fb_mmap callback to work.
> So that's the fake vm_pgoff thing? Doesn't that exist just so
> mmap() through /dev/dri* can be passed a "gem handle"?
> With fbdev mmap we already know which BO we want to map so
> why would any of that stuff even be needed?


I was mainly concentrating on  using drm mmap API to achieve fb_mmap 
which eventually will call i915_gem_mmap()

and expects a  fake offset for the obj. I see your point: fb_mmap can be 
done without using drm mmap API which should be much simple . I will 
look into this and resend.


Thanks,

Nirmoy

>> Regards,
>> Nirmoy
>>
>>>> Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
>>>> ---
>>>>    drivers/gpu/drm/i915/display/intel_dpt.c           | 4 +++-
>>>>    drivers/gpu/drm/i915/display/intel_fbdev.c         | 3 ++-
>>>>    drivers/gpu/drm/i915/display/intel_plane_initial.c | 3 ++-
>>>>    3 files changed, 7 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/i915/display/intel_dpt.c b/drivers/gpu/drm/i915/display/intel_dpt.c
>>>> index ad1a37b515fb..2e6238881860 100644
>>>> --- a/drivers/gpu/drm/i915/display/intel_dpt.c
>>>> +++ b/drivers/gpu/drm/i915/display/intel_dpt.c
>>>> @@ -254,7 +254,9 @@ intel_dpt_create(struct intel_framebuffer *fb)
>>>>    
>>>>    	size = round_up(size * sizeof(gen8_pte_t), I915_GTT_PAGE_SIZE);
>>>>    
>>>> -	dpt_obj = i915_gem_object_create_lmem(i915, size, I915_BO_ALLOC_CONTIGUOUS);
>>>> +	dpt_obj = i915_gem_object_create_lmem(i915, size,
>>>> +					      I915_BO_ALLOC_CONTIGUOUS |
>>>> +					      I915_BO_ALLOC_USER);
>>>>    	if (IS_ERR(dpt_obj) && i915_ggtt_has_aperture(to_gt(i915)->ggtt))
>>>>    		dpt_obj = i915_gem_object_create_stolen(i915, size);
>>>>    	if (IS_ERR(dpt_obj) && !HAS_LMEM(i915)) {
>>>> diff --git a/drivers/gpu/drm/i915/display/intel_fbdev.c b/drivers/gpu/drm/i915/display/intel_fbdev.c
>>>> index 3659350061a7..98ae3a3a986a 100644
>>>> --- a/drivers/gpu/drm/i915/display/intel_fbdev.c
>>>> +++ b/drivers/gpu/drm/i915/display/intel_fbdev.c
>>>> @@ -163,7 +163,8 @@ static int intelfb_alloc(struct drm_fb_helper *helper,
>>>>    	obj = ERR_PTR(-ENODEV);
>>>>    	if (HAS_LMEM(dev_priv)) {
>>>>    		obj = i915_gem_object_create_lmem(dev_priv, size,
>>>> -						  I915_BO_ALLOC_CONTIGUOUS);
>>>> +						  I915_BO_ALLOC_CONTIGUOUS |
>>>> +						  I915_BO_ALLOC_USER);
>>>>    	} else {
>>>>    		/*
>>>>    		 * If the FB is too big, just don't use it since fbdev is not very
>>>> diff --git a/drivers/gpu/drm/i915/display/intel_plane_initial.c b/drivers/gpu/drm/i915/display/intel_plane_initial.c
>>>> index bb6ea7de5c61..4a3680f6a3f5 100644
>>>> --- a/drivers/gpu/drm/i915/display/intel_plane_initial.c
>>>> +++ b/drivers/gpu/drm/i915/display/intel_plane_initial.c
>>>> @@ -110,7 +110,8 @@ initial_plane_vma(struct drm_i915_private *i915,
>>>>    	    size * 2 > i915->dsm.usable_size)
>>>>    		return NULL;
>>>>    
>>>> -	obj = i915_gem_object_create_region_at(mem, phys_base, size, 0);
>>>> +	obj = i915_gem_object_create_region_at(mem, phys_base, size,
>>>> +					       I915_BO_ALLOC_USER);
>>>>    	if (IS_ERR(obj))
>>>>    		return NULL;
>>>>    
>>>> -- 
>>>> 2.39.0