Performance regression in ast drm driver

[Jean Delvare]

Hi David,

The following commit:

commit 7cf321d118a825c1541b43ca45294126fd474efa
Author: Dave Airlie
Date:   Mon Oct 24 15:37:48 2016 +1000

    drm/drivers: add support for using the arch wc mapping API.

is causing a huge performance regression for the ast drm driver. In a
text console, if I call "cat" on a large text file, it takes almost
twice as much time to be displayed and scrolled completely.

Can you please check that the ast driver portion of that commit is both
correct and complete?

Thanks,
-- 
Jean Delvare
SUSE L3 Support