  We performed non-LTE calculations for O I with the plane-parallel model
atmospheres for a set of stellar parameters corresponding to A-K type stars.
The model atom of Przybilla et al. (2000) was updated using the best
theoretical and experimental atomic data available so far. Non-LTE leads to
strengthening the O I lines, and the difference between the non-LTE and LTE
abundances (non-LTE correction) is negative. The departures from LTE grow
toward higher effective temperature and lower surface gravity. In the entire
temperature range and log g = 4, the non-LTE correction does not exceed 0.05
dex in absolute value for O I lines in the visible spectral range. The non-LTE
corrections are significantly larger for the infrared O I 7771-5 A lines and
reach -1.9 dex in the model atmosphere with Teff = 10000 K and log g = 2. To
differentiate the effects of inelastic collisions with electrons and neutral
hydrogen atoms on the statistical equilibrium (SE) of O I, we derived the
oxygen abundance for the three well studied A-type stars Vega, Sirius, and HD
32115. For each star, non-LTE leads to smaller difference between the infrared
and visible lines. For example, for Vega, this difference reduces from 1.17 dex
in LTE down to 0.14 dex when ignoring LTE. To remove the difference between the
infrared and visible lines in A-type stars completely, one needs to reduce the
used electron-impact excitation rates by Barklem (2007) by a factor of 4. In
the case of Procyon and the Sun, inelastic collisions with H I affect the SE of
O I, and agreement between the abundances from different lines is achieved when
using the Drawin's formalism to compute collisional rates. The solar mean
oxygen abundance from the O I 6300, 6158, 7771-5, and 8446 A lines is log
epsilon = 8.74+-0.05, when using the MAFAGS-OS solar model atmosphere and log
epsilon = 8.78+-0.03, when applying the 3D corrections from the literature.
