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drivers: net: dsa: felix: don't restart PCS SGMII AN if not needed 

Some PHYs like VSC8234 don't like it when AN restarts on their system side
and they restart line side AN too, going into an endless link up/down loop.
Don't restart PCS AN if link is up already.

Suggested-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Alex Marginean <alexandru.marginean@nxp.com>
(cherry picked from commit b44d30035850423fda60c932e866c70a01bd1250)
5.4-rM2-2.2.x-imx-squashed
Alex Marginean 2020-01-15 15:49:11 +02:00 committed by Jason Liu
parent 7dcadb8d92
commit da7b2dcc47
1 changed files with 15 additions and 0 deletions
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15
drivers/net/dsa/ocelot/felix_vsc9959.c
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@ -648,7 +648,22 @@ static void vsc9959_pcs_init_sgmii(struct phy_device *pcs,
unsigned int link_an_mode,
const struct phylink_link_state *state)
{
int bmsr, bmcr;
if (link_an_mode == MLO_AN_INBAND) {
/* Some PHYs like VSC8234 don't like it when AN restarts on
* their system side and they restart line side AN too, going
* into an endless link up/down loop. Don't restart PCS AN if
* link is up already.
* We do check that AN is enabled just in case this is the 1st
* call, PCS detects a carrier but AN is disabled from power on
* or by boot loader.
*/
bmcr = phy_read(pcs, MII_BMCR);
bmsr = phy_read(pcs, MII_BMSR);
if ((bmcr & BMCR_ANENABLE) && (bmsr & BMSR_LSTATUS))
return;
/* SGMII spec requires tx_config_Reg[15:0] to be exactly 0x4001
* for the MAC PCS in order to acknowledge the AN.
*/