On 08/27/2018 02:55 PM, Ville Syrjälä wrote:
> On Sat, Aug 25, 2018 at 03:54:17PM -0400, Mikulas Patocka wrote:
>> 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@xxxxxxxxxx>
>>
>> ---
>> 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@xxxxxx>
Patch queued for 4.20, thanks.
Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics
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