Module Name:    src
Committed By:   riastradh
Date:           Sun Dec 19 12:28:27 UTC 2021

Modified Files:
        src/sys/arch/arm/rockchip: rk_drm.c rk_drm.h rk_fb.c

Log Message:
rockchip/drm: use an explicit task queue to avoid config_defer pitfalls.

Author: phone <m...@netbsd.org>
Committer: Taylor R Campbell <riastr...@netbsd.org>


To generate a diff of this commit:
cvs rdiff -u -r1.11 -r1.12 src/sys/arch/arm/rockchip/rk_drm.c
cvs rdiff -u -r1.1 -r1.2 src/sys/arch/arm/rockchip/rk_drm.h
cvs rdiff -u -r1.4 -r1.5 src/sys/arch/arm/rockchip/rk_fb.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.

Modified files:

Index: src/sys/arch/arm/rockchip/rk_drm.c
diff -u src/sys/arch/arm/rockchip/rk_drm.c:1.11 src/sys/arch/arm/rockchip/rk_drm.c:1.12
--- src/sys/arch/arm/rockchip/rk_drm.c:1.11	Sun Dec 19 11:25:48 2021
+++ src/sys/arch/arm/rockchip/rk_drm.c	Sun Dec 19 12:28:27 2021
@@ -1,4 +1,4 @@
-/* $NetBSD: rk_drm.c,v 1.11 2021/12/19 11:25:48 riastradh Exp $ */
+/* $NetBSD: rk_drm.c,v 1.12 2021/12/19 12:28:27 riastradh Exp $ */
 
 /*-
  * Copyright (c) 2019 Jared D. McNeill <jmcne...@invisible.ca>
@@ -27,7 +27,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: rk_drm.c,v 1.11 2021/12/19 11:25:48 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: rk_drm.c,v 1.12 2021/12/19 12:28:27 riastradh Exp $");
 
 #include <sys/param.h>
 #include <sys/bus.h>
@@ -82,6 +82,8 @@ static void	rk_drm_disable_vblank(struct
 static int	rk_drm_load(struct drm_device *, unsigned long);
 static void	rk_drm_unload(struct drm_device *);
 
+static void	rk_drm_task_work(struct work *, void *);
+
 static struct drm_driver rk_drm_driver = {
 	.driver_features = DRIVER_MODESET | DRIVER_GEM,
 	.dev_priv_size = 0,
@@ -131,6 +133,14 @@ rk_drm_attach(device_t parent, device_t 
 	sc->sc_dmat = faa->faa_dmat;
 	sc->sc_bst = faa->faa_bst;
 	sc->sc_phandle = faa->faa_phandle;
+	sc->sc_task_thread = NULL;
+	SIMPLEQ_INIT(&sc->sc_tasks);
+	if (workqueue_create(&sc->sc_task_wq, "rkdrm",
+	    &rk_drm_task_work, NULL, PRI_NONE, IPL_NONE, WQ_MPSAFE)) {
+		aprint_error_dev(self, "unable to create workqueue\n");
+		sc->sc_task_wq = NULL;
+		return;
+	}
 
 	aprint_naive("\n");
 
@@ -164,16 +174,40 @@ rk_drm_init(device_t dev)
 	struct drm_driver * const driver = &rk_drm_driver;
 	int error;
 
+	/*
+	 * Cause any tasks issued synchronously during attach to be
+	 * processed at the end of this function.
+	 */
+	sc->sc_task_thread = curlwp;
+
 	error = -drm_dev_register(sc->sc_ddev, 0);
 	if (error) {
 		aprint_error_dev(dev, "couldn't register DRM device: %d\n",
 		    error);
-		return;
+		goto out;
 	}
+	sc->sc_dev_registered = true;
 
 	aprint_normal_dev(dev, "initialized %s %d.%d.%d %s on minor %d\n",
 	    driver->name, driver->major, driver->minor, driver->patchlevel,
 	    driver->date, sc->sc_ddev->primary->index);
+
+	/*
+	 * Process asynchronous tasks queued synchronously during
+	 * attach.  This will be for display detection to attach a
+	 * framebuffer, so we have the opportunity for a console device
+	 * to attach before autoconf has completed, in time for init(8)
+	 * to find that console without panicking.
+	 */
+	while (!SIMPLEQ_EMPTY(&sc->sc_tasks)) {
+		struct rk_drm_task *const task = SIMPLEQ_FIRST(&sc->sc_tasks);
+
+		SIMPLEQ_REMOVE_HEAD(&sc->sc_tasks, rdt_u.queue);
+		(*task->rdt_fn)(task);
+	}
+
+out:	/* Cause any subesquent tasks to be processed by the workqueue.  */
+	atomic_store_relaxed(&sc->sc_task_thread, NULL);
 }
 
 static vmem_t *
@@ -484,3 +518,31 @@ rk_drm_port_device(struct fdt_device_por
 
 	return NULL;
 }
+
+static void
+rk_drm_task_work(struct work *work, void *cookie)
+{
+	struct rk_drm_task *task = container_of(work, struct rk_drm_task,
+	    rdt_u.work);
+
+	(*task->rdt_fn)(task);
+}
+
+void
+rk_task_init(struct rk_drm_task *task,
+    void (*fn)(struct rk_drm_task *))
+{
+
+	task->rdt_fn = fn;
+}
+
+void
+rk_task_schedule(device_t self, struct rk_drm_task *task)
+{
+	struct rk_drm_softc *sc = device_private(self);
+
+	if (atomic_load_relaxed(&sc->sc_task_thread) == curlwp)
+		SIMPLEQ_INSERT_TAIL(&sc->sc_tasks, task, rdt_u.queue);
+	else
+		workqueue_enqueue(sc->sc_task_wq, &task->rdt_u.work, NULL);
+}

Index: src/sys/arch/arm/rockchip/rk_drm.h
diff -u src/sys/arch/arm/rockchip/rk_drm.h:1.1 src/sys/arch/arm/rockchip/rk_drm.h:1.2
--- src/sys/arch/arm/rockchip/rk_drm.h:1.1	Sat Nov  9 23:30:14 2019
+++ src/sys/arch/arm/rockchip/rk_drm.h	Sun Dec 19 12:28:27 2021
@@ -1,4 +1,4 @@
-/* $NetBSD: rk_drm.h,v 1.1 2019/11/09 23:30:14 jmcneill Exp $ */
+/* $NetBSD: rk_drm.h,v 1.2 2021/12/19 12:28:27 riastradh Exp $ */
 
 /*-
  * Copyright (c) 2019 Jared D. McNeill <jmcne...@invisible.ca>
@@ -29,6 +29,7 @@
 #ifndef _ARM_RK_DRM_H
 #define _ARM_RK_DRM_H
 
+#include <sys/workqueue.h>
 #include <drm/drm_fb_helper.h>
 #include <drm/drm_gem_cma_helper.h>
 
@@ -62,6 +63,12 @@ struct rk_drm_softc {
 
 	int			sc_phandle;
 
+	struct lwp			*sc_task_thread;
+	SIMPLEQ_HEAD(, rk_drm_task)	sc_tasks;
+	struct workqueue		*sc_task_wq;
+
+	bool			sc_dev_registered;
+
 	struct rk_drm_vblank	sc_vbl[RK_DRM_MAX_CRTC];
 };
 
@@ -90,10 +97,22 @@ struct rk_drmfb_attach_args {
 	uint32_t		sfa_fb_linebytes;
 };
 
+struct rk_drm_task {
+	union {
+		SIMPLEQ_ENTRY(rk_drm_task)	queue;
+		struct work			work;
+	}		rdt_u;
+	void		(*rdt_fn)(struct rk_drm_task *);
+};
+
 #define rk_drm_private(ddev)		(ddev)->dev_private
 #define	to_rk_drm_framebuffer(x)	container_of(x, struct rk_drm_framebuffer, base)
 
 int	rk_drm_register_port(int, struct fdt_device_ports *);
 struct drm_device *rk_drm_port_device(struct fdt_device_ports *);
 
+void	rk_task_init(struct rk_drm_task *,
+	    void (*)(struct rk_drm_task *));
+void	rk_task_schedule(device_t, struct rk_drm_task *);
+
 #endif /* _ARM_RK_DRM_H */

Index: src/sys/arch/arm/rockchip/rk_fb.c
diff -u src/sys/arch/arm/rockchip/rk_fb.c:1.4 src/sys/arch/arm/rockchip/rk_fb.c:1.5
--- src/sys/arch/arm/rockchip/rk_fb.c:1.4	Sun Dec 19 11:01:10 2021
+++ src/sys/arch/arm/rockchip/rk_fb.c	Sun Dec 19 12:28:27 2021
@@ -1,4 +1,4 @@
-/* $NetBSD: rk_fb.c,v 1.4 2021/12/19 11:01:10 riastradh Exp $ */
+/* $NetBSD: rk_fb.c,v 1.5 2021/12/19 12:28:27 riastradh Exp $ */
 
 /*-
  * Copyright (c) 2015-2019 Jared McNeill <jmcne...@invisible.ca>
@@ -29,7 +29,7 @@
 #include "opt_wsdisplay_compat.h"
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: rk_fb.c,v 1.4 2021/12/19 11:01:10 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: rk_fb.c,v 1.5 2021/12/19 12:28:27 riastradh Exp $");
 
 #include <sys/param.h>
 #include <sys/bus.h>
@@ -45,6 +45,8 @@ __KERNEL_RCSID(0, "$NetBSD: rk_fb.c,v 1.
 static int	rk_fb_match(device_t, cfdata_t, void *);
 static void	rk_fb_attach(device_t, device_t, void *);
 
+static void	rk_fb_init(struct rk_drm_task *);
+
 static bool	rk_fb_shutdown(device_t, int);
 
 struct rk_fb_softc {
@@ -52,6 +54,7 @@ struct rk_fb_softc {
 	device_t		sc_dev;
 	struct rk_drm_framebuffer *sc_fb;
 	struct rk_drmfb_attach_args sc_sfa;
+	struct rk_drm_task	sc_attach_task;
 };
 
 static paddr_t	rk_fb_mmapfb(struct drmfb_softc *, off_t, int);
@@ -77,7 +80,6 @@ rk_fb_attach(device_t parent, device_t s
 {
 	struct rk_fb_softc * const sc = device_private(self);
 	struct rk_drmfb_attach_args * const sfa = aux;
-	int error;
 
 	sc->sc_dev = self;
 	sc->sc_sfa = *sfa;
@@ -92,6 +94,19 @@ rk_fb_attach(device_t parent, device_t s
 	prop_dictionary_set_bool(dict, "is_console", is_console);
 #endif
 
+	rk_task_init(&sc->sc_attach_task, &rk_fb_init);
+	rk_task_schedule(parent, &sc->sc_attach_task);
+}
+
+static void
+rk_fb_init(struct rk_drm_task *task)
+{
+	struct rk_fb_softc * const sc =
+	    container_of(task, struct rk_fb_softc, sc_attach_task);
+	device_t self = sc->sc_dev;
+	struct rk_drmfb_attach_args * const sfa = &sc->sc_sfa;
+	int error;
+
 	const struct drmfb_attach_args da = {
 		.da_dev = self,
 		.da_fb_helper = sfa->sfa_fb_helper,

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