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[v3,1/2] net: dp83822: disable false carrier interrupt

Message ID 20220623134645.1858361-2-enguerrand.de-ribaucourt@savoirfairelinux.com (mailing list archive)
State Accepted
Commit c96614eeab663646f57f67aa591e015abd8bd0ba
Delegated to: Netdev Maintainers
Headers show
Series net: dp83822: fix interrupt floods | expand

Checks

Context Check Description
netdev/tree_selection success Guessed tree name to be net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix warning Target tree name not specified in the subject
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/cc_maintainers fail 3 blamed authors not CCed: afd@ti.com f.fainelli@gmail.com dmurphy@ti.com; 6 maintainers not CCed: f.fainelli@gmail.com dmurphy@ti.com afd@ti.com pabeni@redhat.com kuba@kernel.org edumazet@google.com
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 7 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Enguerrand de Ribaucourt June 23, 2022, 1:46 p.m. UTC 
When unplugging an Ethernet cable, false carrier events were produced by
the PHY at a very high rate. Once the false carrier counter full, an
interrupt was triggered every few clock cycles until the cable was
replugged. This resulted in approximately 10k/s interrupts.

Since the false carrier counter (FCSCR) is never used, we can safely
disable this interrupt.

In addition to improving performance, this also solved MDIO read
timeouts I was randomly encountering with an i.MX8 fec MAC because of
the interrupt flood. The interrupt count and MDIO timeout fix were
tested on a v5.4.110 kernel.

Signed-off-by: Enguerrand de Ribaucourt <enguerrand.de-ribaucourt@savoirfairelinux.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Fixes: 87461f7a58ab ("net: phy: DP83822 initial driver submission")
---
 drivers/net/phy/dp83822.c | 1 -
 1 file changed, 1 deletion(-)

Comments

Andrew Lunn June 23, 2022, 6:27 p.m. UTC | #1 
On Thu, Jun 23, 2022 at 03:46:44PM +0200, Enguerrand de Ribaucourt wrote:
> When unplugging an Ethernet cable, false carrier events were produced by
> the PHY at a very high rate. Once the false carrier counter full, an
> interrupt was triggered every few clock cycles until the cable was
> replugged. This resulted in approximately 10k/s interrupts.
> 
> Since the false carrier counter (FCSCR) is never used, we can safely
> disable this interrupt.
> 
> In addition to improving performance, this also solved MDIO read
> timeouts I was randomly encountering with an i.MX8 fec MAC because of
> the interrupt flood. The interrupt count and MDIO timeout fix were
> tested on a v5.4.110 kernel.
> 
> Signed-off-by: Enguerrand de Ribaucourt <enguerrand.de-ribaucourt@savoirfairelinux.com>
> Reviewed-by: Andrew Lunn <andrew@lunn.ch>
> Fixes: 87461f7a58ab ("net: phy: DP83822 initial driver submission")

For future reference, you should put these in the opposite order. Your
Signed-off-by should come last. Fixes generally comes first.

No need to resend for this patchset.

   Andrew
diff mbox series

Patch

diff --git a/drivers/net/phy/dp83822.c b/drivers/net/phy/dp83822.c
index e6ad3a494d32..95ef507053a6 100644
--- a/drivers/net/phy/dp83822.c
+++ b/drivers/net/phy/dp83822.c
@@ -230,7 +230,6 @@  static int dp83822_config_intr(struct phy_device *phydev)
 			return misr_status;
 
 		misr_status |= (DP83822_RX_ERR_HF_INT_EN |
-				DP83822_FALSE_CARRIER_HF_INT_EN |
 				DP83822_LINK_STAT_INT_EN |
 				DP83822_ENERGY_DET_INT_EN |
 				DP83822_LINK_QUAL_INT_EN);