[SRU][Trusty][PATCH 1/1] drm/ast: Fixed system hanged if disable P2A

[Juerg Haefliger]

From: "Y.C. Chen" <yc_chen at aspeedtech.com>

BugLink: https://bugs.launchpad.net/bugs/1788817

The original ast driver will access some BMC configuration through P2A bridge
that can be disabled since AST2300 and after.
It will cause system hanged if P2A bridge is disabled.
Here is the update to fix it.

Signed-off-by: Y.C. Chen <yc_chen at aspeedtech.com>
Signed-off-by: Dave Airlie <airlied at redhat.com>

(backported from commit 6c971c09f38704513c426ba6515f22fb3d6c87d5)
[juergh: Adjusted context.]
Signed-off-by: Juerg Haefliger <juergh at canonical.com>
---
 drivers/gpu/drm/ast/ast_drv.h  |   1 +
 drivers/gpu/drm/ast/ast_main.c | 134 +++++++++++++++++----------------
 drivers/gpu/drm/ast/ast_post.c |  10 ++-
 3 files changed, 77 insertions(+), 68 deletions(-)

diff --git a/drivers/gpu/drm/ast/ast_drv.h b/drivers/gpu/drm/ast/ast_drv.h
index 3fc122306f1f..96d1e21e0a6a 100644
--- a/drivers/gpu/drm/ast/ast_drv.h
+++ b/drivers/gpu/drm/ast/ast_drv.h
@@ -102,6 +102,7 @@ struct ast_private {
 	 * we have. */
 	struct ttm_bo_kmap_obj cache_kmap;
 	int next_cursor;
+	bool DisableP2A;
 };
 
 int ast_driver_load(struct drm_device *dev, unsigned long flags);
diff --git a/drivers/gpu/drm/ast/ast_main.c b/drivers/gpu/drm/ast/ast_main.c
index dc4da6ac131d..7748abfd8afa 100644
--- a/drivers/gpu/drm/ast/ast_main.c
+++ b/drivers/gpu/drm/ast/ast_main.c
@@ -66,6 +66,7 @@ uint8_t ast_get_index_reg_mask(struct ast_private *ast,
 static int ast_detect_chip(struct drm_device *dev)
 {
 	struct ast_private *ast = dev->dev_private;
+	uint32_t data;
 	ast_open_key(ast);
 
 	if (dev->pdev->device == PCI_CHIP_AST1180) {
@@ -76,7 +77,6 @@ static int ast_detect_chip(struct drm_device *dev)
 			ast->chip = AST2300;
 			DRM_INFO("AST 2300 detected\n");
 		} else if (dev->pdev->revision >= 0x10) {
-			uint32_t data;
 			ast_write32(ast, 0xf004, 0x1e6e0000);
 			ast_write32(ast, 0xf000, 0x1);
 
@@ -105,6 +105,13 @@ static int ast_detect_chip(struct drm_device *dev)
 			DRM_INFO("AST 2000 detected\n");
 		}
 	}
+
+	/* Check P2A Access */
+	ast->DisableP2A = true;
+	data = ast_read32(ast, 0xf004);
+	if (data != 0xFFFFFFFF)
+		ast->DisableP2A = false;
+
 	return 0;
 }
 
@@ -114,79 +121,78 @@ static int ast_get_dram_info(struct drm_device *dev)
 	uint32_t data, data2;
 	uint32_t denum, num, div, ref_pll;
 
-	ast_write32(ast, 0xf004, 0x1e6e0000);
-	ast_write32(ast, 0xf000, 0x1);
-
+	if (ast->DisableP2A) {
+		ast->dram_bus_width = 16;
+		ast->dram_type = AST_DRAM_1Gx16;
+		ast->mclk = 396;
+	} else {
+		ast_write32(ast, 0xf004, 0x1e6e0000);
+		ast_write32(ast, 0xf000, 0x1);
+		data = ast_read32(ast, 0x10004);
 
-	ast_write32(ast, 0x10000, 0xfc600309);
+		if (data & 0x40)
+			ast->dram_bus_width = 16;
+		else
+			ast->dram_bus_width = 32;
 
-	do {
-		;
-	} while (ast_read32(ast, 0x10000) != 0x01);
-	data = ast_read32(ast, 0x10004);
+		if (ast->chip == AST2300) {
+			switch (data & 0x03) {
+			case 0:
+				ast->dram_type = AST_DRAM_512Mx16;
+				break;
+			default:
+			case 1:
+				ast->dram_type = AST_DRAM_1Gx16;
+				break;
+			case 2:
+				ast->dram_type = AST_DRAM_2Gx16;
+				break;
+			case 3:
+				ast->dram_type = AST_DRAM_4Gx16;
+				break;
+			}
+		} else {
+			switch (data & 0x0c) {
+			case 0:
+			case 4:
+				ast->dram_type = AST_DRAM_512Mx16;
+				break;
+			case 8:
+				if (data & 0x40)
+					ast->dram_type = AST_DRAM_1Gx16;
+				else
+					ast->dram_type = AST_DRAM_512Mx32;
+				break;
+			case 0xc:
+				ast->dram_type = AST_DRAM_1Gx32;
+				break;
+			}
+		}
 
-	if (data & 0x40)
-		ast->dram_bus_width = 16;
-	else
-		ast->dram_bus_width = 32;
+		data = ast_read32(ast, 0x10120);
+		data2 = ast_read32(ast, 0x10170);
+		if (data2 & 0x2000)
+			ref_pll = 14318;
+		else
+			ref_pll = 12000;
 
-	if (ast->chip == AST2300) {
-		switch (data & 0x03) {
-		case 0:
-			ast->dram_type = AST_DRAM_512Mx16;
-			break;
-		default:
-		case 1:
-			ast->dram_type = AST_DRAM_1Gx16;
-			break;
-		case 2:
-			ast->dram_type = AST_DRAM_2Gx16;
-			break;
+		denum = data & 0x1f;
+		num = (data & 0x3fe0) >> 5;
+		data = (data & 0xc000) >> 14;
+		switch (data) {
 		case 3:
-			ast->dram_type = AST_DRAM_4Gx16;
+			div = 0x4;
 			break;
-		}
-	} else {
-		switch (data & 0x0c) {
-		case 0:
-		case 4:
-			ast->dram_type = AST_DRAM_512Mx16;
-			break;
-		case 8:
-			if (data & 0x40)
-				ast->dram_type = AST_DRAM_1Gx16;
-			else
-				ast->dram_type = AST_DRAM_512Mx32;
+		case 2:
+		case 1:
+			div = 0x2;
 			break;
-		case 0xc:
-			ast->dram_type = AST_DRAM_1Gx32;
+		default:
+			div = 0x1;
 			break;
 		}
+		ast->mclk = ref_pll * (num + 2) / (denum + 2) * (div * 1000);
 	}
-
-	data = ast_read32(ast, 0x10120);
-	data2 = ast_read32(ast, 0x10170);
-	if (data2 & 0x2000)
-		ref_pll = 14318;
-	else
-		ref_pll = 12000;
-
-	denum = data & 0x1f;
-	num = (data & 0x3fe0) >> 5;
-	data = (data & 0xc000) >> 14;
-	switch (data) {
-	case 3:
-		div = 0x4;
-		break;
-	case 2:
-	case 1:
-		div = 0x2;
-		break;
-	default:
-		div = 0x1;
-		break;
-	}
-	ast->mclk = ref_pll * (num + 2) / (denum + 2) * (div * 1000);
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/ast/ast_post.c b/drivers/gpu/drm/ast/ast_post.c
index 977cfb35837a..511e1ba78fb1 100644
--- a/drivers/gpu/drm/ast/ast_post.c
+++ b/drivers/gpu/drm/ast/ast_post.c
@@ -365,10 +365,12 @@ void ast_post_gpu(struct drm_device *dev)
 	ast_open_key(ast);
 	ast_set_def_ext_reg(dev);
 
-	if (ast->chip == AST2300)
-		ast_init_dram_2300(dev);
-	else
-		ast_init_dram_reg(dev);
+	if (ast->DisableP2A == false) {
+		if (ast->chip == AST2300)
+			ast_init_dram_2300(dev);
+		else
+			ast_init_dram_reg(dev);
+	}
 }
 
 /* AST 2300 DRAM settings */
-- 
2.17.1