Re: [PATCH 4/10] atyfb: set FBINFO_READS_FAST

On Thu, 23 Jan 2014, Linus Torvalds wrote:

Hmm. You're doing this for Matrix and now the aty driver.

Maybe the problem is at the fbcon level? Depending on
FBINFO_READS_FAST to decide whether you should scroll or rewrite
sounds a bit silly: even if a device doesn't have fast reads, maybe it
has a fast accelerated BLIT operation and scrolls quickly. Should the
fbcon test perhaps be for FBINFO_READS_FAST _or_ the
FBINFO_HWACCEL_COPYAREA bits?

Both mach64 and matrox have a hardware bitter that is faster than 
rewriting the console - that's why FBINFO_READS_FAST improves performance 
for them.

One could improve generic framebuffer core to benchmark the performance of 
scrolling using blitter and rewrite and select FBINFO_READS_FAST 
automatically...

Mikulas

I dunno. I didn't actually check the ->bcopy implementations, maybe
they don't use copyarea. So I'm just going by a general "this feels
wrong" feeling..

                Linus

On Thu, Jan 23, 2014 at 10:18 AM, Mikulas Patocka [off-list ref] wrote:

quoted

Set FBINFO_READS_FAST so that the console code uses scrolling instead of
rewriting. This improves scrolling speed.