diff mbox series

[3/3] mach64: optimize wait_for_fifo

Message ID alpine.LRH.2.02.1808251551570.8284@file01.intranet.prod.int.rdu2.redhat.com (mailing list archive)
State New, archived
Headers show
Series [1/3] mach64: fix display corruption on big endian machines | expand

Commit Message

Mikulas Patocka Aug. 25, 2018, 7:54 p.m. UTC 
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(-)

Comments

Ville Syrjälä Aug. 27, 2018, 12:55 p.m. UTC | #1 
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@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>

> +	}
> +	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)
Bartlomiej Zolnierkiewicz Oct. 8, 2018, 10:38 a.m. UTC | #2 
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@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>

Patch queued for 4.20, thanks.

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics
diff mbox series

Patch

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);
+	}
+	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)