[RFC PATCH 2/2] drm/i915/display: Implement fb_mmap callback function

[Das, Nirmoy]

Hi Jani,

On 3/17/2023 10:39 AM, Jani Nikula wrote:
> On Thu, 16 Mar 2023, Nirmoy Das <nirmoy.das at intel.com> wrote:
>> If stolen memory allocation fails for fbdev, the driver will
>> fallback to system memory. Calculation of smem_start is wrong
>> for such framebuffer objs if the platform comes with no gmadr or
>> no aperture. Solve this by adding fb_mmap callback which will
>> use GTT if aperture is available otherwise will use cpu to access
>> the framebuffer.
>>
>> Cc: Matthew Auld <matthew.auld at intel.com>
>> Cc: Andi Shyti <andi.shyti at linux.intel.com>
>> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
>> Cc: Jani Nikula <jani.nikula at intel.com>
>> Cc: Imre Deak <imre.deak at intel.com>
>> Signed-off-by: Nirmoy Das <nirmoy.das at intel.com>
>> ---
>>   drivers/gpu/drm/i915/display/intel_fbdev.c | 13 +++++++++++++
>>   1 file changed, 13 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/display/intel_fbdev.c b/drivers/gpu/drm/i915/display/intel_fbdev.c
>> index 673bcdfb7ff6..51d6fa034b00 100644
>> --- a/drivers/gpu/drm/i915/display/intel_fbdev.c
>> +++ b/drivers/gpu/drm/i915/display/intel_fbdev.c
>> @@ -40,8 +40,10 @@
>>   #include <drm/drm_crtc.h>
>>   #include <drm/drm_fb_helper.h>
>>   #include <drm/drm_fourcc.h>
>> +#include <drm/drm_gem_framebuffer_helper.h>
>>   
>>   #include "gem/i915_gem_lmem.h"
>> +#include "gem/i915_gem_mman.h"
>>   
>>   #include "i915_drv.h"
>>   #include "intel_display_types.h"
>> @@ -120,6 +122,16 @@ static int intel_fbdev_pan_display(struct fb_var_screeninfo *var,
>>   	return ret;
>>   }
>>   
>> +#define to_intel_fbdev(x) container_of(x, struct intel_fbdev, helper)
> I'd add that as a function (rather than a macro) in a separate patch,
> converting the existing users while at it.


Now I do see there are 5 instance of  this conversion. I will convert 
that into a function in a separate patch.


Thanks,

Nirmoy

>
> BR,
> Jani.
>
>
>> +static int intel_fbdev_mmap(struct fb_info *info, struct vm_area_struct *vma)
>> +{
>> +	struct intel_fbdev *fbdev = to_intel_fbdev(info->par);
>> +	struct drm_gem_object *bo = drm_gem_fb_get_obj(&fbdev->fb->base, 0);
>> +	struct drm_i915_gem_object *obj = to_intel_bo(bo);
>> +
>> +	return i915_gem_fb_mmap(obj, vma);
>> +}
>> +
>>   static const struct fb_ops intelfb_ops = {
>>   	.owner = THIS_MODULE,
>>   	DRM_FB_HELPER_DEFAULT_OPS,
>> @@ -131,6 +143,7 @@ static const struct fb_ops intelfb_ops = {
>>   	.fb_imageblit = drm_fb_helper_cfb_imageblit,
>>   	.fb_pan_display = intel_fbdev_pan_display,
>>   	.fb_blank = intel_fbdev_blank,
>> +	.fb_mmap = intel_fbdev_mmap,
>>   };
>>   
>>   static int intelfb_alloc(struct drm_fb_helper *helper,