New patch to review for coreboot: 696dc0b Fixes to enable RC6 on IvyBridge

[Stefan Reinauer]

Stefan Reinauer ([e-mail]) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/1268

-gerrit

commit 696dc0b6d66d34d0c15798f365387ff8f1436e17
Author: Duncan Laurie 
Date:   Fri May 25 10:04:17 2012 -0700

Fixes to enable RC6 on IvyBridge

- The unneeded poll on non-MT force-wake bit was timing out
    and causing the gma_pm_init_pre_vbios() function to exit
    early so it was not preparing PM registers properly.
    I changed the gtt_poll() calls to not return on timeout
    unless it can't proceed so we don't see half-initialized
    registers.

- RC6+ (Deep Render Standby) is not working reliably so we
    can just enable RC6 in the BIOS and let the kernel decide
    if it wants to enable RC6+ later.

This Kernel message is new in kernel 3.4:
    [drm] Enabling RC6 states: RC6 on, RC6p off, RC6pp off

Change-Id: I69d005ba56be8c7684a4ea1133a1d761f7c07acc
    Signed-off-by: Duncan Laurie 
---
 src/northbridge/intel/sandybridge/gma.c |   59 +++++++++++--------------------
 1 files changed, 21 insertions(+), 38 deletions(-)

diff --git a/src/northbridge/intel/sandybridge/gma.c b/src/northbridge/intel/sandybridge/gma.c
index 499f347..9a8b631 100644
--- a/src/northbridge/intel/sandybridge/gma.c
+++ b/src/northbridge/intel/sandybridge/gma.c
@@ -374,19 +374,11 @@ static void gma_pm_init_pre_vbios(struct device *dev)
    if (bridge_silicon_revision() < IVB_STEP_C0) {
    	/* 1: Enable force wake */
    	gtt_write(0xa18c, 0x00000001);
-		if (!gtt_poll(0x130090, (1 << 0), (1 << 0)))
-			return;
+		gtt_poll(0x130090, (1 << 0), (1 << 0));
    } else {
    	gtt_write(0xa180, 1 << 5);
    	gtt_write(0xa188, 0xffff0001);
-		if (!gtt_poll(0x130040, (1 << 0), (1 << 0)))
-			return;
-		/*
-		 * HACK: also poll on 0x130090, for some reason graphics does
-		 * not work on all SKUs unless this register is polled at boot.
-		 */
-		if (!gtt_poll(0x130090, (1 << 0), (1 << 0)))
-			return;
+		gtt_poll(0x130040, (1 << 0), (1 << 0));
    }

if ((bridge_silicon_revision() & BASE_REV_MASK) == BASE_REV_SNB) {
@@ -432,7 +424,7 @@ static void gma_pm_init_pre_vbios(struct device *dev)
    			gtt_write_powermeter(ivb_pm_gt2_17w);
    		} else if ((tdp >= 25) && (tdp <= 35)) {
    			/* 25W-35W */
-				printk(BIOS_DEBUG, "IVB GT2 35W "
+				printk(BIOS_DEBUG, "IVB GT2 25W-35W "
    			       "Power Meter Weights\n");
    			gtt_write_powermeter(ivb_pm_gt2_35w);
    		} else {
@@ -472,8 +464,7 @@ static void gma_pm_init_pre_vbios(struct device *dev)
    	reg32 &= 0xf;
    	reg32 |= (1 << 1);
    	gtt_write(0x941c, reg32);
-		if (!gtt_poll(0x941c, (1 << 1), (0 << 1)))
-			return;
+		gtt_poll(0x941c, (1 << 1), (0 << 1));
    }

if ((bridge_silicon_revision() & BASE_REV_MASK) == BASE_REV_IVB) {
@@ -489,15 +480,13 @@ static void gma_pm_init_pre_vbios(struct device *dev)
    }

/* 7 */
-	if (!gtt_poll(0x138124, (1 << 31), (0 << 31)))
-		return;
-	gtt_write(0x138128, 0x00000029); /* Mailbox Data */
-	gtt_write(0x138124, 0x80000004); /* Mailbox Cmd for RC6 VID */
-	if (!gtt_poll(0x138124, (1 << 31), (0 << 31)))
-		return;
-	gtt_write(0x138124, 0x8000000a); /* Mailbox Cmd to clear RC6 count */
-	if (!gtt_poll(0x138124, (1 << 31), (0 << 31)))
-		return;
+	if (gtt_poll(0x138124, (1 << 31), (0 << 31))) {
+		gtt_write(0x138128, 0x00000029); /* Mailbox Data */
+		gtt_write(0x138124, 0x80000004); /* Mailbox Cmd for RC6 VID */
+		if (gtt_poll(0x138124, (1 << 31), (0 << 31)))
+			gtt_write(0x138124, 0x8000000a);
+		gtt_poll(0x138124, (1 << 31), (0 << 31));
+	}

/* 8 */
    gtt_write(0xa090, 0x00000000); /* RC Control */
@@ -530,8 +519,13 @@ static void gma_pm_init_pre_vbios(struct device *dev)

/* 11a: Enable Render Standby (RC6) */
    if ((bridge_silicon_revision() & BASE_REV_MASK) == BASE_REV_IVB) {
-		/* on IVB: also enable DeepRenderStandby */
-		gtt_write(0xa090, 0x88060000); /* HW RC Control */
+		/*
+		 * IvyBridge should also support DeepRenderStandby.
+		 *
+		 * Unfortunately it does not work reliably on all SKUs so
+		 * disable it here and it can be enabled by the kernel.
+		 */
+		gtt_write(0xa090, 0x88040000); /* HW RC Control */
    } else {
    	gtt_write(0xa090, 0x88040000); /* HW RC Control */
    }
@@ -566,22 +560,11 @@ static void gma_pm_init_post_vbios(struct device *dev)
    /* 15: Deassert Force Wake */
    if (bridge_silicon_revision() < IVB_STEP_C0) {
    	gtt_write(0xa18c, gtt_read(0xa18c) & ~1);
-		if (!gtt_poll(0x130090, (1 << 0), (0 << 0))) {
-			return;
-		}
+		gtt_poll(0x130090, (1 << 0), (0 << 0));
    } else {
    	gtt_write(0xa188, 0x1fffe);
-		if (!gtt_poll(0x130040, (1 << 0), (0 << 0))) {
-			return;
-		}
-		/*
-		 * HACK: also poll on 0x130090, for some reason graphics does
-		 * not work on all SKUs unless this register is polled at boot.
-		 */
-		if (!gtt_poll(0x130090, (1 << 0), (0 << 0))) {
-			return;
-		}
-		gtt_write(0xa188, gtt_read(0xa188) | 1);
+		if (gtt_poll(0x130040, (1 << 0), (0 << 0)))
+			gtt_write(0xa188, gtt_read(0xa188) | 1);
    }

/* 16: SW RC Control */