From: Matthew Auld <matthew.auld@intel.com>
To: intel-xe@lists.freedesktop.org
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>, dri-devel@lists.freedesktop.org
Subject: [PATCH 01/20] drm/drm_managed: try to improve the drmm DOC
Date: Fri, 10 May 2024 19:12:14 +0100 [thread overview]
Message-ID: <20240510181212.264622-23-matthew.auld@intel.com> (raw)
In-Reply-To: <20240510181212.264622-22-matthew.auld@intel.com>
Hopefully make it clearer when to use devm vs drmm.
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: dri-devel@lists.freedesktop.org
---
drivers/gpu/drm/drm_managed.c | 42 +++++++++++++++++++++++++++++++++++
1 file changed, 42 insertions(+)
diff --git a/drivers/gpu/drm/drm_managed.c b/drivers/gpu/drm/drm_managed.c
index 7646f67bda4e..20d705bbc0a3 100644
--- a/drivers/gpu/drm/drm_managed.c
+++ b/drivers/gpu/drm/drm_managed.c
@@ -34,6 +34,48 @@
* during the lifetime of the driver, all the functions are fully concurrent
* safe. But it is recommended to use managed resources only for resources that
* change rarely, if ever, during the lifetime of the &drm_device instance.
+ *
+ * Note that the distinction between devm and drmm is important to get right.
+ * Consider some hotunplug scenarios, where it is valid for there to be multiple
+ * unplugged struct &drm_device instances each being kept alive by an open
+ * driver fd. The driver needs a clean separation between what needs to happen
+ * when the struct &device is removed and what needs to happen when a given
+ * struct &drm_device instance is released, as well as in some cases a more
+ * finer grained marking of critical sections that require hardware interaction.
+ * See below.
+ *
+ * devm
+ * ~~~~
+ * In general use devm for cleaning up anything hardware related. So removing
+ * pci mmaps, releasing interrupt handlers, basically anything hw related. The
+ * devm release actions are called when the struct &device is removed, shortly
+ * after calling into the drivers struct &pci_driver.remove() callback, if this
+ * is a pci device.
+ *
+ * devm can be thought of as an alternative to putting all the hw related
+ * cleanup directly in the struct &pci_driver.remove() callback, where the
+ * correct ordering of the unwind steps needs to be manually done in the error
+ * path of the struct &pci_driver.probe() and again on the remove side. With
+ * devm this is all done automatically.
+ *
+ * drmm
+ * ~~~~
+ * In general use this for cleaning up anything software related. So data
+ * structures and the like which are tied to the lifetime of a particular struct
+ * &drm_device instance.
+ *
+ * drmm can be thought of as an alternative to putting all the software related
+ * cleanup directly in the struct &drm_driver.release() callback, where again
+ * the correct ordering of the unwind steps needs to be done manually. As with
+ * devm this is instead done automatically.
+ *
+ * Sometimes there is no clean separation between software and hardware, which
+ * is where drm_dev_enter() comes in. For example, a driver might have some
+ * state tied to a struct &drm_device instance, for which the same cleanup path
+ * is called for both a plugged and unplugged device, and the cleanup itself
+ * might require talking to the device if it's still attached to this particular
+ * struct &drm_device. For that we instead mark the device sections. See
+ * drm_dev_enter(), drm_dev_exit() and drm_dev_unplug().
*/
struct drmres_node {
--
2.45.0
next prev parent reply other threads:[~2024-05-10 18:12 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-10 18:12 [PATCH 00/20] core_hotunplug improvements Matthew Auld
2024-05-10 18:12 ` Matthew Auld [this message]
2024-05-13 7:06 ` [PATCH 01/20] drm/drm_managed: try to improve the drmm DOC Andrzej Hajda
2024-05-13 15:38 ` Rodrigo Vivi
2024-05-10 18:12 ` [PATCH 02/20] drm/amdgpu: don't trample pdev drvdata Matthew Auld
2024-05-13 11:54 ` Christian König
2024-05-10 18:12 ` [PATCH 03/20] drm/xe/pci: remove broken driver_release Matthew Auld
2024-05-13 7:14 ` Andrzej Hajda
2024-05-10 18:12 ` [PATCH 04/20] drm/xe: covert sysfs over to devm Matthew Auld
2024-05-10 18:12 ` [PATCH 05/20] drm/xe/ggtt: use drm_dev_enter to mark device section Matthew Auld
2024-05-13 7:16 ` Andrzej Hajda
2024-05-13 19:34 ` Randhawa, Jagmeet
2024-05-10 18:12 ` [PATCH 06/20] drm/xe/guc: move guc_fini over to devm Matthew Auld
2024-05-10 18:12 ` [PATCH 07/20] drm/xe/guc: s/guc_fini/guc_fini_hw/ Matthew Auld
2024-05-13 7:30 ` Andrzej Hajda
2024-05-10 18:12 ` [PATCH 08/20] drm/xe/guc_pc: move pc_fini to devm Matthew Auld
2024-05-10 18:12 ` [PATCH 09/20] drm/xe/guc_pc: s/pc_fini/pc_fini_hw/ Matthew Auld
2024-05-11 9:19 ` kernel test robot
2024-05-13 7:37 ` Andrzej Hajda
2024-05-10 18:12 ` [PATCH 10/20] drm/xe/irq: move irq_uninstall over to devm Matthew Auld
2024-05-10 18:12 ` [PATCH 11/20] drm/xe/device: move flr " Matthew Auld
2024-05-10 18:12 ` [PATCH 12/20] drm/xe/device: move xe_device_sanitize over " Matthew Auld
2024-05-10 18:12 ` [PATCH 13/20] drm/xe/coredump: move " Matthew Auld
2024-05-13 7:38 ` Andrzej Hajda
2024-05-10 18:12 ` [PATCH 14/20] drm/xe/gt: break out gt_fini into sw vs hw state Matthew Auld
2024-05-13 7:50 ` Andrzej Hajda
2024-05-13 8:37 ` Matthew Auld
2024-05-13 9:19 ` Andrzej Hajda
2024-05-10 18:12 ` [PATCH 15/20] drm/xe: make gt_remove use devm Matthew Auld
2024-05-13 7:58 ` Andrzej Hajda
2024-05-10 18:12 ` [PATCH 16/20] drm/xe/mmio: move mmio_fini over to devm Matthew Auld
2024-05-13 8:00 ` Andrzej Hajda
2024-05-10 18:12 ` [PATCH 17/20] drm/xe: reset mmio mappings with devm Matthew Auld
2024-05-13 8:12 ` Andrzej Hajda
2024-05-10 18:12 ` [PATCH 18/20] drm/xe/display: move display fini stuff to devm Matthew Auld
2024-05-13 8:13 ` Andrzej Hajda
2024-05-10 18:12 ` [PATCH 19/20] drm/xe/display: stop calling domains_driver_remove twice Matthew Auld
2024-05-13 8:19 ` Andrzej Hajda
2024-05-13 8:27 ` Matthew Auld
2024-05-13 9:17 ` Andrzej Hajda
2024-05-10 18:12 ` [PATCH 20/20] drm/xe/display: move device_remove over to drmm Matthew Auld
2024-05-11 10:33 ` kernel test robot
2024-05-11 10:43 ` kernel test robot
2024-05-13 8:22 ` Andrzej Hajda
2024-05-10 18:17 ` ✓ CI.Patch_applied: success for core_hotunplug improvements Patchwork
2024-05-10 18:18 ` ✗ CI.checkpatch: warning " Patchwork
2024-05-10 18:18 ` ✗ CI.KUnit: failure " Patchwork
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