Programming PCI SD card reader

Question

I am trying to read a sector from SD card inserted into Realtek 5260 card reader. The card reader is a PCI device attached to the laptop. I issue READ_SINGLE_BLOCK (17) by writing the command and its parameters to the command buffer. The command instructs the reader to use ping pong buffer for the data.

    //read single block
    init_cmd(hDev);

    add_cmd(hDev, WRITE_REG, 0xFDA9, 0xFFu, 0x51u); //SD_CMD0 0x11 | 0x40
    add_cmd(hDev, WRITE_REG, 0xFDAA, 0xFFu, 0); //SD_CMD1
    add_cmd(hDev, WRITE_REG, 0xFDAB, 0xFFu, 0); //SD_CMD2
    add_cmd(hDev, WRITE_REG, 0xFDAC, 0xFFu, 0); //SD_CMD3
    add_cmd(hDev, WRITE_REG, 0xFDAD, 0xFFu, 0); //SD_CMD4

    add_cmd(hDev, WRITE_REG, 0xFDAF, 0xFFu, 0x0); //SD_BYTE_CNT_L
    add_cmd(hDev, WRITE_REG, 0xFDB0, 0xFFu, 0x2); //SD_BYTE_CNT_H
    add_cmd(hDev, WRITE_REG, 0xFDB1, 0xFFu, 0x1); //SD_BLOCK_CNT_L
    add_cmd(hDev, WRITE_REG, 0xFDB2, 0xFFu, 0x0); //SD_BLOCK_CNT_H

    add_cmd(hDev, WRITE_REG, 0xFDA0, 0x3u, 0x1); //SD_CFG1 : bus width

    add_cmd(hDev, WRITE_REG, 0xFDA1, 0xFFu, 0x1); //SD_CFG2 : RSP_TYPE_R1
    add_cmd(hDev, WRITE_REG, 0xFD5B, 1, 1); //CARD_DATA_SOURCE : 1 : RTSX_PINGPONG_BUFFER

    add_cmd(hDev, WRITE_REG, 0xFDB3, 0xFFu, 0x80 | 0xC); //SD_TRANSFER : RTSX_TM_NORMAL_READ
    add_cmd(hDev, CHECK_REG, 0xFDB3, 0x40u, 0x40); //SD_TRANSFER : SD_TRANSFER_END

    send_cmd(hDev);

After issuing READ_SINGLE_BLOCK I program the controller to move data from the ping pong buffer to the command buffer:

    //read ping pong buffer
    init_cmd(hDev);
    DWORD reg = 0xFA00;
    for (DWORD i = 0; i < 0x100; i++)
    {
        add_cmd(hDev, READ_REG, reg, 0, 0);
        reg++;
    }
    send_cmd(hDev);

The problem is that after sending the command and waiting for the interrupt from the device I observe 0s in the command buffer, like if read failed. What can be the reason of the fail? How do I approach such an issue?

Thanks!