drm/ast: POST chip at probe time if VGA not enabled

We need to do it on machines without a BIOS such as POWER8. Also
for detection to work without triggering PCIe errors, we need
to enable VGA early on, inside ast_detect_chip().

While touching those files, replace a few hard coded register
numbers with the corresponding symbolic constant.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 45 insertions, 2 deletions

diff --git a/drivers/gpu/drm/ast/ast_main.c b/drivers/gpu/drm/ast/ast_main.c
index c2ff7933a90e..556d065590cc 100644
--- a/drivers/gpu/drm/ast/ast_main.c
+++ b/drivers/gpu/drm/ast/ast_main.c
@@ -63,7 +63,7 @@ uint8_t ast_get_index_reg_mask(struct ast_private *ast,
 }
 
 
-static int ast_detect_chip(struct drm_device *dev)
+static int ast_detect_chip(struct drm_device *dev, bool *need_post)
 {
         struct ast_private *ast = dev->dev_private;
         uint32_t data, jreg;
@@ -109,6 +109,21 @@ static int ast_detect_chip(struct drm_device *dev)
                 }
         }
 
+        /*
+         * If VGA isn't enabled, we need to enable now or subsequent
+         * access to the scratch registers will fail. We also inform
+         * our caller that it needs to POST the chip
+         * (Assumption: VGA not enabled -> need to POST)
+         */
+        if (!ast_is_vga_enabled(dev)) {
+                ast_enable_vga(dev);
+                ast_enable_mmio(dev);
+                DRM_INFO("VGA not enabled on entry, requesting chip POST\n");
+                *need_post = true;
+        } else
+                *need_post = false;
+
+        /* Check if we support wide screen */
         switch (ast->chip) {
         case AST1180:
                 ast->support_wide_screen = true;
@@ -124,6 +139,7 @@ static int ast_detect_chip(struct drm_device *dev)
                         ast->support_wide_screen = true;
                 else {
                         ast->support_wide_screen = false;
+                        /* Read SCU7c (silicon revision register) */
                         ast_write32(ast, 0xf004, 0x1e6e0000);
                         ast_write32(ast, 0xf000, 0x1);
                         data = ast_read32(ast, 0x1207c);
@@ -136,11 +152,23 @@ static int ast_detect_chip(struct drm_device *dev)
                 break;
         }
 
+        /* Check 3rd Tx option (digital output afaik) */
         ast->tx_chip_type = AST_TX_NONE;
+
+        /*
+         * VGACRA3 Enhanced Color Mode Register, check if DVO is already
+         * enabled, in that case, assume we have a SIL164 TMDS transmitter
+         */
         jreg = ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xa3, 0xff);
         if (jreg & 0x80)
                 ast->tx_chip_type = AST_TX_SIL164;
+
         if ((ast->chip == AST2300) || (ast->chip == AST2400)) {
+                /*
+                 * On AST2300 and 2400, look the configuration set by the SoC in
+                 * the SOC scratch register #1 bits 11:8 (interestingly marked
+                 * as "reserved" in the spec
+                 */
                 jreg = ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xd1, 0xff);
                 switch (jreg) {
                 case 0x04:
@@ -161,6 +189,17 @@ static int ast_detect_chip(struct drm_device *dev)
                 }
         }
 
+        /* Print stuff for diagnostic purposes */
+        switch(ast->tx_chip_type) {
+        case AST_TX_SIL164:
+                DRM_INFO("Using Sil164 TMDS transmitter\n");
+                break;
+        case AST_TX_DP501:
+                DRM_INFO("Using DP501 DisplayPort transmitter\n");
+                break;
+        default:
+                DRM_INFO("Analog VGA only\n");
+        }
         return 0;
 }
 
@@ -345,6 +384,7 @@ static u32 ast_get_vram_info(struct drm_device *dev)
 int ast_driver_load(struct drm_device *dev, unsigned long flags)
 {
         struct ast_private *ast;
+        bool need_post;
         int ret = 0;
 
         ast = kzalloc(sizeof(struct ast_private), GFP_KERNEL);
@@ -379,7 +419,7 @@ int ast_driver_load(struct drm_device *dev, unsigned long flags)
                 }
         }
 
-        ast_detect_chip(dev);
+        ast_detect_chip(dev, &need_post);
 
         if (ast->chip != AST1180) {
                 ast_get_dram_info(dev);
@@ -387,6 +427,9 @@ int ast_driver_load(struct drm_device *dev, unsigned long flags)
                 DRM_INFO("dram %d %d %d %08x\n", ast->mclk, ast->dram_type, ast->dram_bus_width, ast->vram_size);
         }
 
+        if (need_post)
+                ast_post_gpu(dev);
+
         ret = ast_mm_init(ast);
         if (ret)
                 goto out_free;