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 <muva...@gmail.com>

yep. cover letter is good to have.

Reviewed-by: Grygorii Strashko <grygorii.stras...@ti.com>

---
  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(&regs->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