[Intel-gfx] [RFC 0/2] Enable Nearest-neighbor for Integer mode scaling

[Sharma, Shashank]

Hello Ville,

On 9/3/2019 10:50 PM, Ville Syrjälä wrote:
> On Tue, Sep 03, 2019 at 10:22:25PM +0530, Shashank Sharma wrote:
>> Blurry outputs during upscaling the buffer, is a generic problem of gfx
>> industry. One of the major reason behind this blurriness is the
>> interpolation of pixel values used by most of the upscaling hardwares.
>>
>> Nearest-neighbor is a scaling mode, which works by filling in the missing
>> color values in the upscaled image with that of the coordinate-mapped
>> nearest source pixel value.
>>
>> Nearest-neighbor can produce (almost) non-blurry scaling outputs when
>> the scaling ratio is complete integer. For example:
>> - input buffer resolution: 1280x720(HD)
>> - output buffer resolution: 3840x2160(UHD/4K)
>> - scaling ratio (h) = 3840/1280 = 3
>>    scaling ratio (v) = 2160/720 = 3
>> In such scenarios, we should try to pick Nearest-neighbor as scaling
>> method when possible.
>>
>> Many gaming communities have been asking for integer-mode scaling
>> support, some links and background:
>> https://software.intel.com/en-us/articles/integer-scaling-support-on-intel-graphics
>> http://tanalin.com/en/articles/lossless-scaling/
>> https://community.amd.com/thread/209107
>> https://www.nvidia.com/en-us/geforce/forums/game-ready-drivers/13/1002/feature-request-nonblurry-upscaling-at-integer-rat/
>>
>> This patch series enables NN scaling on Intel display (ICL), when the upscaling
>> ratio is integer.
> I think we'd probably want a property for this sort of stuff. igt
> could perhaps also use it to enable crc based scaling tests.
I was initially planning to attach this to scaling mode property, 
probably create a new option in there called "Integer mode scaling" or 
we can use the "maintain aspect ratio" sub-option too. Do you think it 
would make sense ? Or should we create a new property altogether ?
> Another problem is that we currently don't expose the panel fitter
> for external displays so this would be limited to eDP/DSI only.
> I have a branch that implements borders (for underscan) for DP/HDMI
> which is at least moving the code a little bit into a direction where
> we could consider exposing the panel fitter for external displays.

This would be very interesting, do you have any plans to publish this soon ?

- Shashank