vga_switcheroo_lock_ddc — temporarily switch DDC lines to a given client
int vga_switcheroo_lock_ddc ( | struct pci_dev * pdev) ; |
Temporarily switch DDC lines to the client identified by pdev
(but leave the outputs otherwise switched to where they are).
This allows the inactive client to probe EDID. The DDC lines must
afterwards be switched back by calling vga_switcheroo_unlock_ddc
,
even if this function returns an error.
Previous DDC owner on success or a negative int on error.
Specifically, -ENODEV
if no handler has registered or if the handler
does not support switching the DDC lines. Also, a negative value
returned by the handler is propagated back to the caller.
The return value has merely an informational purpose for any caller
which might be interested in it. It is acceptable to ignore the return
value and simply rely on the result of the subsequent EDID probe,
which will be NULL
if DDC switching failed.