mirror of
https://github.com/RT-Thread/rt-thread.git
synced 2025-02-21 01:07:18 +08:00
When the driver request a API gets RT_NULL which return value is ptr, they could not know why get a RT_NULL. some API return RT_NULL, is not error internal maybe, it just not supported for this platform, but the driver still could work ok, the API can return (RT_NULL + -RT_EEMPTY) to driver. on the other hand, the driver can do more behaviors by error no. When the API return the -RT_EBUSY, driver can wait for a moment and retry. When the API return the -RT_ENOSYS, driver can try the next mode or request's name. Signed-off-by: GuEe-GUI <wusongjie@rt-thread.com>