Re: [PATCH v2] drm/ast: Fix long time waiting on s3/s4 resume

From: Thomas Zimmermann
Date: Wed May 24 2023 - 06:41:38 EST

Hi,

sorry that this took so long.

Am 24.05.23 um 04:34 schrieb Jammy Huang:
Hi Thomas,

Could you help review this patch?

This is an issue leading to kernel panic found by Intel. Wendy has confirmed issue resolved by this patch.

On 2023/4/14 下午 03:42, Jammy Huang wrote:
In resume, DP's launch function, ast_dp_launch, could wait at most 30
seconds before timeout to check if DP is enabled.

To avoid this problem, we only check if DP enable or not at driver probe.


You should say what the problem is. Has the DP always been disabled? Is the DP only disabled after resume? Or is it a firmware bug?

If you have the name/email of "wendy.wang", you should probably mention her in a Reported-by tag here.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=217278

This should be

Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217278

Signed-off-by: Jammy Huang <jammy_huang@xxxxxxxxxxxxxx>

With these changes considered, feel free to add

Acked-by: Thomas Zimmermann <tzimmermann@xxxxxxx>

But I cannot test the patch or even verify the bugfix.

I do have comments below that you might want to consider as well.

---
  v2 changes:
   - Fix build error.
---
  drivers/gpu/drm/ast/ast_dp.c   | 55 +++++++++++-----------------------
  drivers/gpu/drm/ast/ast_drv.h  |  2 +-
  drivers/gpu/drm/ast/ast_main.c | 11 +++++--
  drivers/gpu/drm/ast/ast_post.c |  3 +-
  4 files changed, 29 insertions(+), 42 deletions(-)

diff --git a/drivers/gpu/drm/ast/ast_dp.c b/drivers/gpu/drm/ast/ast_dp.c
index 56483860306b..eee2f264c880 100644
--- a/drivers/gpu/drm/ast/ast_dp.c
+++ b/drivers/gpu/drm/ast/ast_dp.c
@@ -119,53 +119,32 @@ int ast_astdp_read_edid(struct drm_device *dev, u8 *ediddata)
  /*
   * Launch Aspeed DP
   */
-void ast_dp_launch(struct drm_device *dev, u8 bPower)
+void ast_dp_launch(struct drm_device *dev)
  {
-    u32 i = 0, j = 0, WaitCount = 1;
-    u8 bDPTX = 0;
+    u32 i = 0;
      u8 bDPExecute = 1;
-
      struct ast_private *ast = to_ast_private(dev);
-    // S3 come back, need more time to wait BMC ready.
-    if (bPower)
-        WaitCount = 300;
-
-
-    // Wait total count by different condition.
-    for (j = 0; j < WaitCount; j++) {
-        bDPTX = ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xD1, TX_TYPE_MASK);
-
-        if (bDPTX)
-            break;
+    // Wait one second then timeout.
+    while (ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xD1, COPROCESSOR_LAUNCH) !=
+        COPROCESSOR_LAUNCH) {
+        i++;
+        // wait 100 ms
          msleep(100);
-    }
-    // 0xE : ASTDP with DPMCU FW handling
-    if (bDPTX == ASTDP_DPMCU_TX) {
-        // Wait one second then timeout.
-        i = 0;
-
-        while (ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xD1, COPROCESSOR_LAUNCH) !=
-            COPROCESSOR_LAUNCH) {
-            i++;
-            // wait 100 ms
-            msleep(100);
-
-            if (i >= 10) {
-                // DP would not be ready.
-                bDPExecute = 0;
-                break;
-            }
+        if (i >= 10) {
+            // DP would not be ready.
+            bDPExecute = 0;
+            break;
          }
+    }
-        if (bDPExecute)
-            ast->tx_chip_types |= BIT(AST_TX_ASTDP);
+    if (!bDPExecute)
+        drm_err(dev, "Wait DPMCU executing timeout\n");

If waiting fails, should the function return an error? The caller could then disable the DP functionality.

-        ast_set_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xE5,
-                            (u8) ~ASTDP_HOST_EDID_READ_DONE_MASK,
-                            ASTDP_HOST_EDID_READ_DONE);
-    }
+    ast_set_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xE5,
+                   (u8) ~ASTDP_HOST_EDID_READ_DONE_MASK,
+                   ASTDP_HOST_EDID_READ_DONE);
  }
diff --git a/drivers/gpu/drm/ast/ast_drv.h b/drivers/gpu/drm/ast/ast_drv.h
index d51b81fea9c8..15e86394be4f 100644
--- a/drivers/gpu/drm/ast/ast_drv.h
+++ b/drivers/gpu/drm/ast/ast_drv.h
@@ -498,7 +498,7 @@ struct ast_i2c_chan *ast_i2c_create(struct drm_device *dev);
  /* aspeed DP */
  int ast_astdp_read_edid(struct drm_device *dev, u8 *ediddata);
-void ast_dp_launch(struct drm_device *dev, u8 bPower);
+void ast_dp_launch(struct drm_device *dev);
  void ast_dp_power_on_off(struct drm_device *dev, bool no);
  void ast_dp_set_on_off(struct drm_device *dev, bool no);
  void ast_dp_set_mode(struct drm_crtc *crtc, struct ast_vbios_mode_info *vbios_mode);
diff --git a/drivers/gpu/drm/ast/ast_main.c b/drivers/gpu/drm/ast/ast_main.c
index f83ce77127cb..8ecddf20113f 100644
--- a/drivers/gpu/drm/ast/ast_main.c
+++ b/drivers/gpu/drm/ast/ast_main.c
@@ -254,8 +254,13 @@ static int ast_detect_chip(struct drm_device *dev, bool *need_post)
          case 0x0c:
              ast->tx_chip_types = AST_TX_DP501_BIT;
          }
-    } else if (ast->chip == AST2600)
-        ast_dp_launch(&ast->base, 0);
+    } else if (ast->chip == AST2600) {
+        if (ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xD1, TX_TYPE_MASK) ==
+            ASTDP_DPMCU_TX) {
+            ast->tx_chip_types = AST_TX_ASTDP_BIT;
+            ast_dp_launch(&ast->base);

Here, if ast_dp_launch() would return an error, we would not set the chip type. The driver would then disable further support. That appears to be preferable to me. (?)

Best regards
Thomas

+        }
+    }
      /* Print stuff for diagnostic purposes */
      if (ast->tx_chip_types & AST_TX_NONE_BIT)
@@ -264,6 +269,8 @@ static int ast_detect_chip(struct drm_device *dev, bool *need_post)
          drm_info(dev, "Using Sil164 TMDS transmitter\n");
      if (ast->tx_chip_types & AST_TX_DP501_BIT)
          drm_info(dev, "Using DP501 DisplayPort transmitter\n");
+    if (ast->tx_chip_types & AST_TX_ASTDP_BIT)
+        drm_info(dev, "Using ASPEED DisplayPort transmitter\n");
      return 0;
  }
diff --git a/drivers/gpu/drm/ast/ast_post.c b/drivers/gpu/drm/ast/ast_post.c
index 82fd3c8adee1..90e40f59aff7 100644
--- a/drivers/gpu/drm/ast/ast_post.c
+++ b/drivers/gpu/drm/ast/ast_post.c
@@ -380,7 +380,8 @@ void ast_post_gpu(struct drm_device *dev)
      ast_set_def_ext_reg(dev);
      if (ast->chip == AST2600) {
-        ast_dp_launch(dev, 1);
+        if (ast->tx_chip_types & AST_TX_ASTDP_BIT)
+            ast_dp_launch(dev);
      } else if (ast->config_mode == ast_use_p2a) {
          if (ast->chip == AST2500)
              ast_post_chip_2500(dev);

base-commit: e62252bc55b6d4eddc6c2bdbf95a448180d6a08d


--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)

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