/* * gpio_backlight.c - Simple GPIO-controlled backlight * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include #include #include #include #include #include #include #include #include #include #include #include struct gpio_backlight { struct device *dev; struct device *fbdev; int gpio; int active; int def_value; }; static int gpio_backlight_update_status(struct backlight_device *bl) { struct gpio_backlight *gbl = bl_get_data(bl); int brightness = bl->props.brightness; if (bl->props.power != FB_BLANK_UNBLANK || bl->props.fb_blank != FB_BLANK_UNBLANK || bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK)) brightness = 0; gpio_set_value_cansleep(gbl->gpio, brightness ? gbl->active : !gbl->active); return 0; } static int gpio_backlight_check_fb(struct backlight_device *bl, struct fb_info *info) { struct gpio_backlight *gbl = bl_get_data(bl); return gbl->fbdev == NULL || gbl->fbdev == info->dev; } static const struct backlight_ops gpio_backlight_ops = { .options = BL_CORE_SUSPENDRESUME, .update_status = gpio_backlight_update_status, .check_fb = gpio_backlight_check_fb, }; static int gpio_backlight_probe_dt(struct platform_device *pdev, struct gpio_backlight *gbl) { struct device_node *np = pdev->dev.of_node; enum of_gpio_flags gpio_flags; gbl->gpio = of_get_gpio_flags(np, 0, &gpio_flags); if (!gpio_is_valid(gbl->gpio)) { if (gbl->gpio != -EPROBE_DEFER) { dev_err(&pdev->dev, "Error: The gpios parameter is missing or invalid.\n"); } return gbl->gpio; } gbl->active = (gpio_flags & OF_GPIO_ACTIVE_LOW) ? 0 : 1; gbl->def_value = of_property_read_bool(np, "default-on"); return 0; } static int gpio_backlight_probe(struct platform_device *pdev) { struct gpio_backlight_platform_data *pdata = dev_get_platdata(&pdev->dev); struct backlight_properties props; struct backlight_device *bl; struct gpio_backlight *gbl; struct device_node *np = pdev->dev.of_node; unsigned long flags = GPIOF_DIR_OUT; int ret; if (!pdata && !np) { dev_err(&pdev->dev, "failed to find platform data or device tree node.\n"); return -ENODEV; } gbl = devm_kzalloc(&pdev->dev, sizeof(*gbl), GFP_KERNEL); if (gbl == NULL) return -ENOMEM; gbl->dev = &pdev->dev; if (np) { ret = gpio_backlight_probe_dt(pdev, gbl); if (ret) return ret; } else { gbl->fbdev = pdata->fbdev; gbl->gpio = pdata->gpio; gbl->active = pdata->active_low ? 0 : 1; gbl->def_value = pdata->def_value; } if (gbl->active) flags |= gbl->def_value ? GPIOF_INIT_HIGH : GPIOF_INIT_LOW; else flags |= gbl->def_value ? GPIOF_INIT_LOW : GPIOF_INIT_HIGH; ret = devm_gpio_request_one(gbl->dev, gbl->gpio, flags, pdata ? pdata->name : "backlight"); if (ret < 0) { dev_err(&pdev->dev, "unable to request GPIO\n"); return ret; } memset(&props, 0, sizeof(props)); props.type = BACKLIGHT_RAW; props.max_brightness = 1; bl = devm_backlight_device_register(&pdev->dev, dev_name(&pdev->dev), &pdev->dev, gbl, &gpio_backlight_ops, &props); if (IS_ERR(bl)) { dev_err(&pdev->dev, "failed to register backlight\n"); return PTR_ERR(bl); } bl->props.brightness = gbl->def_value; backlight_update_status(bl); platform_set_drvdata(pdev, bl); return 0; } #ifdef CONFIG_OF static struct of_device_id gpio_backlight_of_match[] = { { .compatible = "gpio-backlight" }, { /* sentinel */ } }; MODULE_DEVICE_TABLE(of, gpio_backlight_of_match); #endif static struct platform_driver gpio_backlight_driver = { .driver = { .name = "gpio-backlight", .of_match_table = of_match_ptr(gpio_backlight_of_match), }, .probe = gpio_backlight_probe, }; module_platform_driver(gpio_backlight_driver); MODULE_AUTHOR("Laurent Pinchart "); MODULE_DESCRIPTION("GPIO-based Backlight Driver"); MODULE_LICENSE("GPL"); MODULE_ALIAS("platform:gpio-backlight"); s='ctrl'>
authorLinus Torvalds <torvalds@linux-foundation.org>2017-01-29 13:50:06 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-01-29 13:50:06 -0800
commit39cb2c9a316e77f6dfba96c543e55b6672d5a37e (patch)
tree98fe974ee4e20121253de7f61fc8d01bdb3821c1 /sound/soc/intel/atom
parent2c5d9555d6d937966d79d4c6529a5f7b9206e405 (diff)
drm/i915: Check for NULL i915_vma in intel_unpin_fb_obj()
I've seen this trigger twice now, where the i915_gem_object_to_ggtt() call in intel_unpin_fb_obj() returns NULL, resulting in an oops immediately afterwards as the (inlined) call to i915_vma_unpin_fence() tries to dereference it. It seems to be some race condition where the object is going away at shutdown time, since both times happened when shutting down the X server. The call chains were different: - VT ioctl(KDSETMODE, KD_TEXT): intel_cleanup_plane_fb+0x5b/0xa0 [i915] drm_atomic_helper_cleanup_planes+0x6f/0x90 [drm_kms_helper] intel_atomic_commit_tail+0x749/0xfe0 [i915] intel_atomic_commit+0x3cb/0x4f0 [i915] drm_atomic_commit+0x4b/0x50 [drm] restore_fbdev_mode+0x14c/0x2a0 [drm_kms_helper] drm_fb_helper_restore_fbdev_mode_unlocked+0x34/0x80 [drm_kms_helper] drm_fb_helper_set_par+0x2d/0x60 [drm_kms_helper] intel_fbdev_set_par+0x18/0x70 [i915] fb_set_var+0x236/0x460 fbcon_blank+0x30f/0x350 do_unblank_screen+0xd2/0x1a0 vt_ioctl+0x507/0x12a0 tty_ioctl+0x355/0xc30 do_vfs_ioctl+0xa3/0x5e0 SyS_ioctl+0x79/0x90 entry_SYSCALL_64_fastpath+0x13/0x94 - i915 unpin_work workqueue: intel_unpin_work_fn+0x58/0x140 [i915] process_one_work+0x1f1/0x480 worker_thread+0x48/0x4d0 kthread+0x101/0x140 and this patch purely papers over the issue by adding a NULL pointer check and a WARN_ON_ONCE() to avoid the oops that would then generally make the machine unresponsive. Other callers of i915_gem_object_to_ggtt() seem to also check for the returned pointer being NULL and warn about it, so this clearly has happened before in other places. [ Reported it originally to the i915 developers on Jan 8, applying the ugly workaround on my own now after triggering the problem for the second time with no feedback. This is likely to be the same bug reported as https://bugs.freedesktop.org/show_bug.cgi?id=98829 https://bugs.freedesktop.org/show_bug.cgi?id=99134 which has a patch for the underlying problem, but it hasn't gotten to me, so I'm applying the workaround. ] Cc: Daniel Vetter <daniel.vetter@intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: Imre Deak <imre.deak@intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'sound/soc/intel/atom')