  We calculate the angular and temperature $T$ dependencies of the upper
critical field $H_{c2}(\theta,\phi,T)$ for the $C_{4v}$ point group helical
$p$-wave states, assuming a single uniaxial ellipsoidal Fermi surface, Pauli
limiting, and strong spin-orbit coupling that locks the spin-triplet $\vec{\bf
d}$-vectors onto the layers. Good fits to the Sr$_2$RuO$_4$
$H_{c2,a}(\theta,T)$ data of Kittaka {\it et al.} [Phys. Rev. B {\bf 80},
174514 (2009)] are obtained. Helical states with $\vec{\bf d}(\vec{\bf
k})=k_x\vec{\bf x}-k_y\vec{\bf y}$ and $k_y\vec{\bf x}+k_x\vec{\bf y}$ (or
$k_x\vec{\bf x}+k_y\vec{\bf y}$ and $k_y\vec{\bf x}-k_x\vec{\bf y}$) produce
$H_{c2}(90^{\circ},\phi,T)$ that greatly exceed (or do not exhibit) the
four-fold azimuthal anisotropy magnitudes observed in Sr$_2$RuO$_4$ by Kittaka
{\it et al.} and by Mao {\it et al.} [Phys. Rev. Lett. {\bf 84}, 991 (2000)],
respectively.
