On 8/23/2017 18:59, Matthew Tan wrote:
Calls to udelay are not preemtable by userspace so userspace
applications experience a large (~200us) latency when running on core
0. Instead usleep_range can be used to be more friendly to userspace
since it is preemtable. This is due to udelay using busy-wait loops
while usleep_rang uses hrtimers instead. It is recommended to use
udelay when the delay is <10us since at that precision overhead of
usleep_range hrtimer setup causes issues. However, the replaced calls
are for 50us and 100us so this should not be not an issue.
Signed-off-by: Matthew Tan <matthew.ta...@nxp.com>
---
drivers/net/ethernet/intel/e1000e/phy.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/net/ethernet/intel/e1000e/phy.c
b/drivers/net/ethernet/intel/e1000e/phy.c
index de13aea..e318fdc 100644
--- a/drivers/net/ethernet/intel/e1000e/phy.c
+++ b/drivers/net/ethernet/intel/e1000e/phy.c
@@ -158,7 +158,7 @@ s32 e1000e_read_phy_reg_mdic(struct e1000_hw *hw, u32
offset, u16 *data)
* the lower time out
*/
for (i = 0; i < (E1000_GEN_POLL_TIMEOUT * 3); i++) {
- udelay(50);
+ usleep_range(40, 60);
mdic = er32(MDIC);
if (mdic & E1000_MDIC_READY)
break;
@@ -183,7 +183,7 @@ s32 e1000e_read_phy_reg_mdic(struct e1000_hw *hw, u32
offset, u16 *data)
* reading duplicate data in the next MDIC transaction.
*/
if (hw->mac.type == e1000_pch2lan)
- udelay(100);
+ usleep_range(90, 100);
return 0;
}
@@ -222,7 +222,7 @@ s32 e1000e_write_phy_reg_mdic(struct e1000_hw *hw, u32
offset, u16 data)
* the lower time out
*/
for (i = 0; i < (E1000_GEN_POLL_TIMEOUT * 3); i++) {
- udelay(50);
+ usleep_range(40, 60);
mdic = er32(MDIC);
if (mdic & E1000_MDIC_READY)
break;
@@ -246,7 +246,7 @@ s32 e1000e_write_phy_reg_mdic(struct e1000_hw *hw, u32
offset, u16 data)
* reading duplicate data in the next MDIC transaction.
*/
if (hw->mac.type == e1000_pch2lan)
- udelay(100);
+ usleep_range(90, 110);
return 0;
}
Reasonable. Do you have any open bug or other reference describe this
problem?
