Re: [PATCHv2 1/2] drivers: net: davinci_mdio: remove busy loop on wait user access

[David Miller]

From: Max Uvarov 
Date: Thu, 10 Aug 2017 10:47:46 +0300

> Polling 14 mdio devices on single mdio bus eats 30% of 1Ghz cpu time
> due to busy loop in wait(). Add small delay to relax cpu.
> 
> Signed-off-by: Max Uvarov 

Applied to net-next.

Re: [PATCHv2 1/2] drivers: net: davinci_mdio: remove busy loop on wait user access

[Grygorii Strashko]

On 08/10/2017 02:47 AM, Max Uvarov wrote:

Polling 14 mdio devices on single mdio bus eats 30% of 1Ghz cpu time
due to busy loop in wait(). Add small delay to relax cpu.

Signed-off-by: Max Uvarov 


yep. cover letter is good to have.

Reviewed-by: Grygorii Strashko 


---
  v2: fix spelling in commit description.

  drivers/net/ethernet/ti/davinci_mdio.c | 4 +++-
  1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/ti/davinci_mdio.c 
b/drivers/net/ethernet/ti/davinci_mdio.c
index 33df340..611e7cc 100644
--- a/drivers/net/ethernet/ti/davinci_mdio.c
+++ b/drivers/net/ethernet/ti/davinci_mdio.c
@@ -198,8 +198,10 @@ static inline int wait_for_user_access(struct 
davinci_mdio_data *data)
return 0;
  
  		reg = __raw_readl(>control);

-   if ((reg & CONTROL_IDLE) == 0)
+   if ((reg & CONTROL_IDLE) == 0) {
+   usleep_range(100, 200);
continue;
+   }
  
  		/*

 * An emac soft_reset may have clobbered the mdio controller's



--
regards,
-grygorii

Re: [PATCHv2 1/2] drivers: net: davinci_mdio: remove busy loop on wait user access

[Andrew Lunn]

On Thu, Aug 10, 2017 at 10:47:46AM +0300, Max Uvarov wrote:
> Polling 14 mdio devices on single mdio bus eats 30% of 1Ghz cpu time
> due to busy loop in wait(). Add small delay to relax cpu.

Hi Max

Please include a cover note when you have multiple patches in a
series.

With 14 devices, it makes sense to swap to using PHY interrupts if you
can. That should prevent the PHY state machine polling the PHYs every
second.

Reviewed-by: Andrew Lunn 

Andrew

[PATCHv2 1/2] drivers: net: davinci_mdio: remove busy loop on wait user access

[Max Uvarov]

Polling 14 mdio devices on single mdio bus eats 30% of 1Ghz cpu time
due to busy loop in wait(). Add small delay to relax cpu.

Signed-off-by: Max Uvarov 
---
 v2: fix spelling in commit description.

 drivers/net/ethernet/ti/davinci_mdio.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/ti/davinci_mdio.c 
b/drivers/net/ethernet/ti/davinci_mdio.c
index 33df340..611e7cc 100644
--- a/drivers/net/ethernet/ti/davinci_mdio.c
+++ b/drivers/net/ethernet/ti/davinci_mdio.c
@@ -198,8 +198,10 @@ static inline int wait_for_user_access(struct 
davinci_mdio_data *data)
return 0;
 
reg = __raw_readl(>control);
-   if ((reg & CONTROL_IDLE) == 0)
+   if ((reg & CONTROL_IDLE) == 0) {
+   usleep_range(100, 200);
continue;
+   }
 
/*
 * An emac soft_reset may have clobbered the mdio controller's
-- 
2.5.0