[Intel-gfx] [PATCH 10/13] drm/i915: fix the CFB size check

[Maarten Lankhorst]

Op 10-11-15 om 13:20 schreef Zanoni, Paulo R:
> Em Ter, 2015-11-10 às 11:22 +0100, Maarten Lankhorst escreveu:
>> Op 04-11-15 om 20:10 schreef Paulo Zanoni:
>>> In function find_compression_threshold() we try to over-allocate
>>> CFB
>>> space in order to reudce reallocations and fragmentation, and we're
>>> not considering that at the CFB size check. Consider it.
>>>
>>> There is also a longer-term plan to kill
>>> dev_priv->fbc.uncompressed_size, but this will come later.
>>>
>>> Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
>>> ---
>>>  drivers/gpu/drm/i915/intel_fbc.c | 3 ++-
>>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/intel_fbc.c
>>> b/drivers/gpu/drm/i915/intel_fbc.c
>>> index dee99c9..e99aacc 100644
>>> --- a/drivers/gpu/drm/i915/intel_fbc.c
>>> +++ b/drivers/gpu/drm/i915/intel_fbc.c
>>> @@ -719,7 +719,8 @@ static int intel_fbc_setup_cfb(struct
>>> intel_crtc *crtc)
>>>  	size = intel_fbc_calculate_cfb_size(crtc);
>>>  	cpp = drm_format_plane_cpp(fb->pixel_format, 0);
>>>  
>>> -	if (size <= dev_priv->fbc.uncompressed_size)
>>> +	if (dev_priv->fbc.compressed_fb.allocated &&
>>> +	    size <= dev_priv->fbc.compressed_fb.size * dev_priv-
>>>> fbc.threshold)
>>>  		return 0;
>>>  
>>>  	/* Release any current block */
>> Should i8xx_fbc_enable be changed too then?
> As far as I understand, no. We're just reserving a bigger buffer in
> case we need it later, but the size used by the hardware is still the
> same. But I'm not 100% sure the i8xx code is actually correct since I
> didn't dig deep into the ancient scrolls. By not touching i8xx we're
> also avoiding a possible new regression.
>
The original check was for size <= uncompressed_size,
new is threshold * compressed.

I think i8xx_fbc_enable might have to do the same when calculating cfb_pitch
for this patch to work as intended.

~Maarten