Re: [Intel-wired-lan] [PATCH iwl-net v1 1/1] e1000e: change usleep_range to udelay in PHY mdic access

[Paul Menzel]

Dear Vitaly,


Thank you for the patch.


Am 17.04.24 um 21:03 schrieb Vitaly Lifshits:

This is a partial revert of commit 6dbdd4de0362 ("e1000e: Workaround
for sporadic MDI error on Meteor Lake systems"). The referenced commit
introduced an issue on vPro systems, where disconnecting and reconnecting
the LAN cable might result in a kernel panic.

Please paste the panic, and document the test system.

This was root caused to the usage of usleep_range in an atomic content

conte*x*t?

while trying to access the PHY. Change back the usleep_range calls to
udelay.

Please explain, why this is an atomic context.

Fixes: 6dbdd4de0362 ("e1000e: Workaround for sporadic MDI error on Meteor Lake 
systems")
Co-developed-by: Sasha Neftin <sasha.nef...@intel.com>
Signed-off-by: Sasha Neftin <sasha.nef...@intel.com>
Signed-off-by: Vitaly Lifshits <vitaly.lifsh...@intel.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 93544f1cc2a5..f7ae0e0aa4a4 100644
--- a/drivers/net/ethernet/intel/e1000e/phy.c
+++ b/drivers/net/ethernet/intel/e1000e/phy.c
@@ -157,7 +157,7 @@ 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++) {
-                       usleep_range(50, 60);
+                       udelay(50);
                        mdic = er32(MDIC);
                        if (mdic & E1000_MDIC_READY)
                                break;
@@ -181,7 +181,7 @@ 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)
-                       usleep_range(100, 150);
+                       udelay(100);

if (success) {

                        *data = (u16)mdic;
@@ -237,7 +237,7 @@ 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++) {
-                       usleep_range(50, 60);
+                       udelay(50);
                        mdic = er32(MDIC);
                        if (mdic & E1000_MDIC_READY)
                                break;
@@ -261,7 +261,7 @@ 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)
-                       usleep_range(100, 150);
+                       udelay(100);

if (success)

                        return 0;

It’d also be interested where the delay values are specified.


Kind regards,

Paul