[Intel-gfx] [RFC] i915: make the probe asynchronous

[Feng Tang]

Hi Jani/Chris/Takashi, 

On Wed, Jun 06, 2018 at 11:21:43AM +0300, Jani Nikula wrote:
> >> 
> >> http://patchwork.freedesktop.org/patch/msgid/20180323083048.13327-1-chris@chris-wilson.co.uk
> >
> > IIUC, you are waiting for the HDA audio driver to first handle the
> > i915 sync probel case?
> 
> I wouldn't hold my breath waiting. If you want to do i915 async probe,
> you'll probably have to figure hda out as well.

I made the following patch based on 4.18-rc1, and tested on my machine,
which basically works fine with Async probe taking effect (I tried
builtin and modules way).

Please review this initial version, and I'll separate to clean patches
if you think it's OK. thanks!

- Feng


------
diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c
index 4364922..16a59ae 100644
--- a/drivers/gpu/drm/i915/i915_pci.c
+++ b/drivers/gpu/drm/i915/i915_pci.c
@@ -671,6 +671,21 @@ static const struct pci_device_id pciidlist[] = {
 };
 MODULE_DEVICE_TABLE(pci, pciidlist);
 
+static struct completion i915_probe_done;
+
+int wait_i915_probe_done(int timeout)
+{
+	int ret;
+
+	ret = wait_for_completion_interruptible_timeout(&i915_probe_done, timeout);
+	if (ret <= 0)
+		return -ENODEV;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(wait_i915_probe_done);
+
+
 static void i915_pci_remove(struct pci_dev *pdev)
 {
 	struct drm_device *dev = pci_get_drvdata(pdev);
@@ -717,6 +732,7 @@ static int i915_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 		return err > 0 ? -ENOTTY : err;
 	}
 
+	complete_all(&i915_probe_done);
 	return 0;
 }
 
@@ -726,6 +742,7 @@ static struct pci_driver i915_pci_driver = {
 	.probe = i915_pci_probe,
 	.remove = i915_pci_remove,
 	.driver.pm = &i915_pm_ops,
+	.driver.probe_type = PROBE_PREFER_ASYNCHRONOUS,
 };
 
 static int __init i915_init(void)
@@ -755,6 +772,8 @@ static int __init i915_init(void)
 		return 0;
 	}
 
+	init_completion(&i915_probe_done);
+
 	return pci_register_driver(&i915_pci_driver);
 }
 
diff --git a/include/drm/i915_drm.h b/include/drm/i915_drm.h
index c9e5a66..adae172 100644
--- a/include/drm/i915_drm.h
+++ b/include/drm/i915_drm.h
@@ -36,6 +36,12 @@ extern bool i915_gpu_lower(void);
 extern bool i915_gpu_busy(void);
 extern bool i915_gpu_turbo_disable(void);
 
+/*
+ * For use by HDA driver for now
+ * Return 0 on i915 probe is done, and -ENODEV on error
+ */
+extern int wait_i915_probe_done(int timeout);
+
 /* Exported from arch/x86/kernel/early-quirks.c */
 extern struct resource intel_graphics_stolen_res;
 
diff --git a/sound/hda/hdac_i915.c b/sound/hda/hdac_i915.c
index cbe818e..48e5039 100644
--- a/sound/hda/hdac_i915.c
+++ b/sound/hda/hdac_i915.c
@@ -17,6 +17,7 @@
 #include <linux/pci.h>
 #include <linux/component.h>
 #include <drm/i915_component.h>
+#include <drm/i915_drm.h>
 #include <sound/core.h>
 #include <sound/hdaudio.h>
 #include <sound/hda_i915.h>
@@ -357,6 +358,7 @@ static bool i915_gfx_present(void)
  *
  * Returns zero for success or a negative error code.
  */
+#define HDAC_WAIT_I915_LOAD_MS	3000
 int snd_hdac_i915_init(struct hdac_bus *bus)
 {
 	struct component_match *match = NULL;
@@ -386,7 +388,11 @@ int snd_hdac_i915_init(struct hdac_bus *bus)
 	 * Atm, we don't support deferring the component binding, so make sure
 	 * i915 is loaded and that the binding successfully completes.
 	 */
-	request_module("i915");
+	ret = wait_i915_probe_done(HDAC_WAIT_I915_LOAD_MS);
+	if (ret) {
+		dev_info(dev, "failed to wait for i915 probe done\n");
+		goto out_master_del;
+	}
 
 	if (!acomp->ops) {
 		ret = -ENODEV;