[intel] Forcibly skip PHY reset on some models

On some models (notably ICH), the PHY reset mechanism appears to be
broken.  In particular, the PHY_CTRL register will be correctly loaded
from NVM but the values will not be propagated to the "OEM bits" PHY
register.  This typically has the effect of dropping the link speed to
10Mbps.

Since the original version of this driver in commit 945e428 ("[intel]
Replace driver for Intel Gigabit NICs"), we have always worked around
this problem by skipping the PHY reset if the link is already up.
Enhance this workaround by explicitly checking for known-broken PCI
IDs.

Reported-by: Robin Smidsrød <robin@smidsrod.no>
Tested-by: Robin Smidsrød <robin@smidsrod.no>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/net/intel.c

 	writel ( ctrl, intel->regs + INTEL_CTRL );
 	mdelay ( INTEL_RESET_DELAY_MS );
 
-	/* If link is already up, do not attempt to reset the PHY.  On
-	 * some models (notably ICH), performing a PHY reset seems to
-	 * drop the link speed to 10Mbps.
+	/* On some models (notably ICH), the PHY reset mechanism
+	 * appears to be broken.  In particular, the PHY_CTRL register
+	 * will be correctly loaded from NVM but the values will not
+	 * be propagated to the "OEM bits" PHY register.  This
+	 * typically has the effect of dropping the link speed to
+	 * 10Mbps.
+	 *
+	 * Work around this problem by skipping the PHY reset if
+	 * either (a) the link is already up, or (b) this particular
+	 * NIC is known to be broken.
 	 */
 	status = readl ( intel->regs + INTEL_STATUS );
-	if ( status & INTEL_STATUS_LU ) {
-		DBGC ( intel, "INTEL %p MAC reset (ctrl %08x)\n",
-		       intel, ctrl );
+	if ( ( intel->flags & INTEL_NO_PHY_RST ) ||
+	     ( status & INTEL_STATUS_LU ) ) {
+		DBGC ( intel, "INTEL %p %sMAC reset (ctrl %08x)\n", intel,
+		       ( ( intel->flags & INTEL_NO_PHY_RST ) ? "forced " : "" ),
+		       ctrl );
 		return 0;
 	}
 
 	PCI_ROM ( 0x8086, 0x10f5, "82567lm", "82567LM", 0 ),
 	PCI_ROM ( 0x8086, 0x10f6, "82574l", "82574L", 0 ),
 	PCI_ROM ( 0x8086, 0x1501, "82567v-3", "82567V-3", INTEL_PBS_ERRATA ),
-	PCI_ROM ( 0x8086, 0x1502, "82579lm", "82579LM", 0 ),
+	PCI_ROM ( 0x8086, 0x1502, "82579lm", "82579LM", INTEL_NO_PHY_RST ),
 	PCI_ROM ( 0x8086, 0x1503, "82579v", "82579V", 0 ),
 	PCI_ROM ( 0x8086, 0x150a, "82576ns", "82576NS", 0 ),
 	PCI_ROM ( 0x8086, 0x150c, "82583v", "82583V", 0 ),
 	PCI_ROM ( 0x8086, 0x15a0, "i218lm-2", "I218-LM", 0 ),
 	PCI_ROM ( 0x8086, 0x15a1, "i218v-2", "I218-V", 0 ),
 	PCI_ROM ( 0x8086, 0x15a2, "i218lm-3", "I218-LM", 0 ),
-	PCI_ROM ( 0x8086, 0x15a3, "i218v-3", "I218-V", 0 ),
+	PCI_ROM ( 0x8086, 0x15a3, "i218v-3", "I218-V", INTEL_NO_PHY_RST ),
 	PCI_ROM ( 0x8086, 0x294c, "82566dc-2", "82566DC-2", 0 ),
 	PCI_ROM ( 0x8086, 0x2e6e, "cemedia", "CE Media Processor", 0 ),
 };

src/drivers/net/intel.h

 	INTEL_PBS_ERRATA = 0x0001,
 	/** VMware missing interrupt workaround required */
 	INTEL_VMWARE = 0x0002,
+	/** PHY reset is broken */
+	INTEL_NO_PHY_RST = 0x0004,
 };
 
 /**