[PATCH] drm/amd/display: Fix cursor pos and hotspot calcs

[Kazlauskas, Nicholas]

On 12/12/18 9:10 AM, Michel Dänzer wrote:
> On 2018-12-12 3:04 p.m., Nicholas Kazlauskas wrote:
>> [Why]
>> The cursor calculations in amdgpu_dm incorrectly assume that the
>> cursor hotspot is always (0, 0) and don't respect the hot_x and hot_y
>> attributes that can be passed in via the drm_mode_cursor2_ioctl.
>>
>> The DC hotspot parameters are also incorrectly used to offset the
>> cursor when it goes beyond the bounds of the screen instead of
>> being clamped.
>>
>> [How]
>> Use the hot_x and hot_y attributes from the fb to directly fill in the
>> DC hotspot attributes.
>>
>> Clamp the cursor position on the edges of the screen instead of using
>> the hotspot to offset it back in.
>>
>> Cc: Leo Li <sunpeng.li at amd.com>
>> Cc: Harry Wentland <harry.wentland at amd.com>
>> Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas at amd.com>
>> ---
>>   .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 23 +++++++------------
>>   1 file changed, 8 insertions(+), 15 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>> index 01badda14079..61f2eae0b67f 100644
>> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>> @@ -4266,7 +4266,6 @@ static int get_cursor_position(struct drm_plane *plane, struct drm_crtc *crtc,
>>   {
>>   	struct amdgpu_crtc *amdgpu_crtc = to_amdgpu_crtc(crtc);
>>   	int x, y;
>> -	int xorigin = 0, yorigin = 0;
>>   
>>   	if (!crtc || !plane->state->fb) {
>>   		position->enable = false;
>> @@ -4284,24 +4283,18 @@ static int get_cursor_position(struct drm_plane *plane, struct drm_crtc *crtc,
>>   		return -EINVAL;
>>   	}
>>   
>> -	x = plane->state->crtc_x;
>> -	y = plane->state->crtc_y;
>> +	x = plane->state->crtc_x + plane->state->fb->hot_x;
>> +	y = plane->state->crtc_y + plane->state->fb->hot_y;
>> +
>>   	/* avivo cursor are offset into the total surface */
>>   	x += crtc->primary->state->src_x >> 16;
>>   	y += crtc->primary->state->src_y >> 16;
>> -	if (x < 0) {
>> -		xorigin = min(-x, amdgpu_crtc->max_cursor_width - 1);
>> -		x = 0;
>> -	}
>> -	if (y < 0) {
>> -		yorigin = min(-y, amdgpu_crtc->max_cursor_height - 1);
>> -		y = 0;
>> -	}
>> +
>>   	position->enable = true;
>> -	position->x = x;
>> -	position->y = y;
>> -	position->x_hotspot = xorigin;
>> -	position->y_hotspot = yorigin;
>> +	position->x = x >= 0 ? x : 0;
>> +	position->y = y >= 0 ? y : 0;
>> +	position->x_hotspot = plane->state->fb->hot_x;
>> +	position->y_hotspot = plane->state->fb->hot_y;
> 
> I don't see how this could work correctly. Try moving a cursor which
> doesn't have the hot spot at the top/left edge (e.g. the X-shaped cursor
> used by an X server without any clients) beyond the top/left edge of the
> monitor.
> 
> 
Do you mean the clamping? I was just keeping the driver's previous 
behavior regarding this.

It previously forced the position to 0 but offset the cursor using the 
hotspot attribute the more it sunk into the top or left edge. You can 
see this with the default GNOME3 cursor (which doesn't have a hotspot of 
0, 0) and it sinks into the edge on the screen by a few pixels.

With this patch the cursor position is now always aligned with the first 
black pixel instead of the white border - and not just whenever it 
starts sinking into the top or left edge.

Nicholas Kazlauskas