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[realtek] Work around hardware bug on RTL8211B 

The RTL8211B seems to have a bug that prevents the link from coming up
unless the MII_MMD_DATA register is cleared.

The Linux kernel driver applies this workaround (in rtl8211b_resume())
only to the specific RTL8211B PHY model, along with a matching
workaround to set bit 9 of MII_MMD_DATA when suspending the PHY.
Since we have no need to ever suspend the PHY, and since writing a
zero ought to be harmless, we just clear the register unconditionally.

Debugged-by: Nikolay Pertsev <nikolay.p@cos.flag.org>
Tested-by: Nikolay Pertsev <nikolay.p@cos.flag.org>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
pull/397/head
Michael Brown 2021-06-22 14:48:10 +01:00
parent 0688114ea6
commit 5622575c5e
2 changed files with 12 additions and 0 deletions
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10
src/drivers/net/realtek.c
View File

@ -420,6 +420,16 @@ static int realtek_phy_reset ( struct realtek_nic *rtl ) {
*/
}
/* Some cards (e.g. RTL8211B) have a hardware errata that
* requires the MII_MMD_DATA register to be cleared before the
* link will come up.
*/
if ( ( rc = mii_write ( &rtl->mii, MII_MMD_DATA, 0 ) ) != 0 ) {
/* Ignore failures, since the register may not be
* present on all PHYs.
*/
}
/* Restart autonegotiation */
if ( ( rc = mii_restart ( &rtl->mii ) ) != 0 ) {
DBGC ( rtl, "REALTEK %p could not restart MII: %s\n",

2
src/include/mii.h
View File

@ -23,6 +23,8 @@ FILE_LICENCE ( GPL2_ONLY );
#define MII_EXPANSION 0x06 /* Expansion register */
#define MII_CTRL1000 0x09 /* 1000BASE-T control */
#define MII_STAT1000 0x0a /* 1000BASE-T status */
#define MII_MMD_CTRL 0x0d /* MMD Access Control Register */
#define MII_MMD_DATA 0x0e /* MMD Access Data Register */
#define MII_ESTATUS 0x0f /* Extended Status */
#define MII_DCOUNTER 0x12 /* Disconnect counter */
#define MII_FCSCOUNTER 0x13 /* False carrier counter */