Re: [PATCH 3/3] mach64: optimize wait_for_fifo
From: Ville Syrjälä <syrjala@sci.fi>
Date: 2018-08-27 12:55:40
Also in:
dri-devel
On Sat, Aug 25, 2018 at 03:54:17PM -0400, Mikulas Patocka wrote:
quoted hunk ↗ jump to hunk
This is a simple optimization for fifo waiting that improves scrolling performance by 5%. If the queue has more free entries that what we consume, we can skip the costly register read next time. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> --- drivers/video/fbdev/aty/atyfb.h | 12 ++++++++---- drivers/video/fbdev/aty/mach64_accel.c | 4 +++- 2 files changed, 11 insertions(+), 5 deletions(-) Index: linux-stable/drivers/video/fbdev/aty/atyfb.h =================================> --- linux-stable.orig/drivers/video/fbdev/aty/atyfb.h 2018-08-25 21:49:16.000000000 +0200+++ linux-stable/drivers/video/fbdev/aty/atyfb.h 2018-08-25 21:52:51.000000000 +0200@@ -147,6 +147,7 @@ struct atyfb_par { u16 pci_id; u32 accel_flags; int blitter_may_be_busy; + unsigned fifo_space; int asleep; int lock_blank; unsigned long res_start;@@ -346,10 +347,13 @@ extern int aty_init_cursor(struct fb_inf * Hardware acceleration */ -static inline void wait_for_fifo(u16 entries, const struct atyfb_par *par) +static inline void wait_for_fifo(u16 entries, struct atyfb_par *par) { - while ((aty_ld_le32(FIFO_STAT, par) & 0xffff) > - ((u32) (0x8000 >> entries))); + unsigned fifo_space = par->fifo_space; + while (entries > fifo_space) { + fifo_space = 16 - fls(aty_ld_le32(FIFO_STAT, par) & 0xffff);
I don't recall off hand which way this register works, but based on the existing code this looks correct. Reviewed-by: Ville Syrjälä <syrjala@sci.fi>
quoted hunk ↗ jump to hunk
+ } + par->fifo_space = fifo_space - entries; } static inline void wait_for_idle(struct atyfb_par *par)@@ -359,7 +363,7 @@ static inline void wait_for_idle(struct par->blitter_may_be_busy = 0; } -extern void aty_reset_engine(const struct atyfb_par *par); +extern void aty_reset_engine(struct atyfb_par *par); extern void aty_init_engine(struct atyfb_par *par, struct fb_info *info); void atyfb_copyarea(struct fb_info *info, const struct fb_copyarea *area);Index: linux-stable/drivers/video/fbdev/aty/mach64_accel.c =================================> --- linux-stable.orig/drivers/video/fbdev/aty/mach64_accel.c 2018-08-25 21:49:16.000000000 +0200+++ linux-stable/drivers/video/fbdev/aty/mach64_accel.c 2018-08-25 21:49:16.000000000 +0200@@ -37,7 +37,7 @@ static u32 rotation24bpp(u32 dx, u32 dir return ((rotation << 8) | DST_24_ROTATION_ENABLE); } -void aty_reset_engine(const struct atyfb_par *par) +void aty_reset_engine(struct atyfb_par *par) { /* reset engine */ aty_st_le32(GEN_TEST_CNTL,@@ -50,6 +50,8 @@ void aty_reset_engine(const struct atyfb /* HOST errors */ aty_st_le32(BUS_CNTL, aty_ld_le32(BUS_CNTL, par) | BUS_HOST_ERR_ACK | BUS_FIFO_ERR_ACK, par); + + par->fifo_space = 0; } static void reset_GTC_3D_engine(const struct atyfb_par *par)
-- Ville Syrjälä syrjala@sci.fi http://www.sci.fi/~syrjala/