[PATCH net-next] net: pcs: lynx: fix lynx_pcs_link_up_sgmii() not doing anything in fixed-link mode

[PATCH net-next] net: pcs: lynx: fix lynx_pcs_link_up_sgmii() not doing anything in fixed-link mode

[Vladimir Oltean]

lynx_pcs_link_up_sgmii() is supposed to update the PCS speed and duplex
for the non-inband operating modes, and prior to the blamed commit, it
did just that, but a mistake sneaked into the conversion and reversed
the condition.

It is easy for this to go undetected on platforms that also initialize
the PCS in the bootloader, because Linux doesn't reset it (although
maybe it should). The nature of the bug is that phylink will not touch
the IF_MODE_HALF_DUPLEX | IF_MODE_SPEED_MSK fields when it should, and
it will apparently keep working if the previous values set by the
bootloader were correct.

Fixes: c689a6528c22 ("net: pcs: lynx: update PCS driver to use neg_mode")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
 drivers/net/pcs/pcs-lynx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/pcs/pcs-lynx.c b/drivers/net/pcs/pcs-lynx.c
index 9021b96d4f9d..dc3962b2aa6b 100644
--- a/drivers/net/pcs/pcs-lynx.c
+++ b/drivers/net/pcs/pcs-lynx.c
@@ -216,7 +216,7 @@ static void lynx_pcs_link_up_sgmii(struct mdio_device *pcs,
 	/* The PCS needs to be configured manually only
 	 * when not operating on in-band mode
 	 */
-	if (neg_mode != PHYLINK_PCS_NEG_INBAND_ENABLED)
+	if (neg_mode == PHYLINK_PCS_NEG_INBAND_ENABLED)
 		return;
 
 	if (duplex == DUPLEX_HALF)
-- 
2.34.1

Re: [PATCH net-next] net: pcs: lynx: fix lynx_pcs_link_up_sgmii() not doing anything in fixed-link mode

[Russell King (Oracle)]

On Fri, Aug 11, 2023 at 02:53:52PM +0300, Vladimir Oltean wrote:
> lynx_pcs_link_up_sgmii() is supposed to update the PCS speed and duplex
> for the non-inband operating modes, and prior to the blamed commit, it
> did just that, but a mistake sneaked into the conversion and reversed
> the condition.

Yes, it certainly looks that way, thanks for catching this.

> It is easy for this to go undetected on platforms that also initialize
> the PCS in the bootloader, because Linux doesn't reset it (although
> maybe it should). The nature of the bug is that phylink will not touch
> the IF_MODE_HALF_DUPLEX | IF_MODE_SPEED_MSK fields when it should, and
> it will apparently keep working if the previous values set by the
> bootloader were correct.
> 
> Fixes: c689a6528c22 ("net: pcs: lynx: update PCS driver to use neg_mode")
> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>

Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

Thanks!

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Re: [PATCH net-next] net: pcs: lynx: fix lynx_pcs_link_up_sgmii() not doing anything in fixed-link mode

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by David S. Miller <davem@davemloft.net>:

On Fri, 11 Aug 2023 14:53:52 +0300 you wrote:
> lynx_pcs_link_up_sgmii() is supposed to update the PCS speed and duplex
> for the non-inband operating modes, and prior to the blamed commit, it
> did just that, but a mistake sneaked into the conversion and reversed
> the condition.
> 
> It is easy for this to go undetected on platforms that also initialize
> the PCS in the bootloader, because Linux doesn't reset it (although
> maybe it should). The nature of the bug is that phylink will not touch
> the IF_MODE_HALF_DUPLEX | IF_MODE_SPEED_MSK fields when it should, and
> it will apparently keep working if the previous values set by the
> bootloader were correct.
> 
> [...]

Here is the summary with links:
  - [net-next] net: pcs: lynx: fix lynx_pcs_link_up_sgmii() not doing anything in fixed-link mode
    https://git.kernel.org/netdev/net-next/c/2f4503f94c5d

You are awesome, thank you!
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