Switch from UHD to FHD. GPU Scaling make blurred fonts. How to fix it?

[stav-ag]

I have laptop with 980m and AUO109B UHD panel.

When i change resolution from native 3840x2160 to 1920x1080 (x1/2), i have blurred fonts. In control panel i have only GPU scaling mode. Adding custom full-hd resolution with CRU not activating Display scaling. When check (set) some established resolution in CRU, then Display scaling appears, but set the full-hd resolution make screen black.

What parameters may activate Display scaling? or i need to modify nvidia driver to set it's scale filter to pixel perfect?

[ToastyX]

You can't do display scaling with a laptop because a laptop display doesn't have a scaler. I don't think there's a way to make the GPU scale with pixel doubling. If this is for desktop use, you'd be better off using 3840x2160 and setting the Windows DPI scaling to 200%.

[stav-ag]

With this simple code (using NVAPI) we can switch between scale modes.

Code:

#include <stdio.h>
#include <windows.h>
#include "nvapi.h"

int _tmain(int argc, _TCHAR* argv[])
{
    NvAPI_Status ret = NVAPI_OK;
    NvU32 totalTargets = 0;
    NvU32 DisplayID = 0;
    NvU32 pathCount = 0;
    NV_DISPLAYCONFIG_PATH_INFO *pathInfo = NULL;
    NvDisplayHandle *pNvDispHandle = NULL;

    ret = NvAPI_Initialize();
    if (ret != NVAPI_OK)
    {
        printf("NvAPI_Initialize() failed = 0x%x", ret);
        return 1; // Initialization failed
    }

    //Retrieve the display path information
    ret = NvAPI_DISP_GetDisplayConfig(&pathCount, NULL);
    if (ret != NVAPI_OK)    return ret;

    pathInfo = (NV_DISPLAYCONFIG_PATH_INFO*)malloc(pathCount * sizeof(NV_DISPLAYCONFIG_PATH_INFO));
    if (!pathInfo)
    {
        return NVAPI_OUT_OF_MEMORY;
    }

    memset(pathInfo, 0, pathCount * sizeof(NV_DISPLAYCONFIG_PATH_INFO));
    for (NvU32 i = 0; i < pathCount; i++)
    {
        pathInfo[i].version = NV_DISPLAYCONFIG_PATH_INFO_VER;
    }

    // Retrieve the targetInfo counts
    ret = NvAPI_DISP_GetDisplayConfig(&pathCount, pathInfo);
    if (ret != NVAPI_OK)
    {
        return ret;
    }

    for (NvU32 i = 0; i < pathCount; i++)
    {
        // Allocate the source mode info
        pathInfo[i].sourceModeInfo = (NV_DISPLAYCONFIG_SOURCE_MODE_INFO*)malloc(sizeof(NV_DISPLAYCONFIG_SOURCE_MODE_I​NFO));
        if (pathInfo[i].sourceModeInfo == NULL)
        {
            return NVAPI_OUT_OF_MEMORY;
        }
        memset(pathInfo[i].sourceModeInfo, 0, sizeof(NV_DISPLAYCONFIG_SOURCE_MODE_INFO));

        // Allocate the target array
        pathInfo[i].targetInfo = (NV_DISPLAYCONFIG_PATH_TARGET_INFO*)malloc(pathInfo[i].targetInfoCount * sizeof(NV_DISPLAYCONFIG_PATH_TARGET_INFO));
        if (pathInfo[i].targetInfo == NULL)
        {
            return NVAPI_OUT_OF_MEMORY;
        }
        // Allocate the target details
        memset(pathInfo[i].targetInfo, 0, pathInfo[i].targetInfoCount * sizeof(NV_DISPLAYCONFIG_PATH_TARGET_INFO));
        for (NvU32 j = 0; j < pathInfo[i].targetInfoCount; j++)
        {
            pathInfo[i].targetInfo[j].details = (NV_DISPLAYCONFIG_PATH_ADVANCED_TARGET_INFO*)malloc(sizeof(NV_DISPLAYCONFIG_PATH​_ADVANCED_TARGET_INFO));
            memset(pathInfo[i].targetInfo[j].details, 0, sizeof(NV_DISPLAYCONFIG_PATH_ADVANCED_TARGET_INFO));
            pathInfo[i].targetInfo[j].details->version = NV_DISPLAYCONFIG_PATH_ADVANCED_TARGET_INFO_VER;
        }
    }

    // Retrieve the full path info
    ret = NvAPI_DISP_GetDisplayConfig(&pathCount, pathInfo);
    if (ret != NVAPI_OK)
    {
        return ret;
    }

    // swap scaling mode
    pathInfo[0].targetInfo[0].details->scaling =(pathInfo[0].targetInfo[0].details->scaling == NV_SCALING_GPU_SCANOUT_TO_NATIVE) ? NV_SCALING_GPU_SCALING_TO_NATIVE : NV_SCALING_GPU_SCANOUT_TO_NATIVE;

    ret = NvAPI_DISP_SetDisplayConfig(1, pathInfo, NV_DISPLAYCONFIG_DRIVER_RELOAD_ALLOWED); // NV_DISPLAYCONFIG_DRIVER_RELOAD_ALLOWED
    if (ret != NVAPI_OK)
    {
        printf("Failed to Set Mode... return code = 0x%x", ret);
        return 1;//Failed to Set Mode
    }

    printf("\nPress any key to exit...");
    getchar();

    return 0;
}

Maybe someone can help go deep in NvAPI_DISP_SetDisplayConfig function? I suppose that scaling modes are hidden inside the driver (not a DWM). Like hidden:
NvAPI_D3D10_ProcessCallbacks
NvAPI_D3D10_GetBufferStreamOutBytesWritten
NvAPI_D3D10_SetBufferStreamOutBytesWritten

Also i found old petition
https://www.change.org/p/nvidia-allow-di...pu-drivers
it's 3 years old