The Accretion-Ejection Instability and a "Magnetic Flood" scenario for GRS 1915+105

I present a global view of recent results on the Accretion-Ejection Instability (AEI), described in more details in other contributions to this workshop. These results address essentially the characteristics of the AEI as a good candidate to explain the low-frequency QPO of X-ray binaries, in particular (at $\sim 1-10$ Hz) of micro-quasars. I then discuss how, if the AEI is considered as the source of the QPO, a possible scenario can be considered where the $\sim 30$ mn. cycles of GRS 1915+105 are controlled by the evolution of magnetic flux in the disk.