From 935774cd71fe604cc8ed24adcb507d7784255672 Mon Sep 17 00:00:00 2001 From: Brian Starkey Date: Wed, 29 Mar 2017 17:42:32 +0100 Subject: drm: Add writeback connector type Writeback connectors represent writeback engines which can write the CRTC output to a memory framebuffer. Add a writeback connector type and related support functions. Drivers should initialize a writeback connector with drm_writeback_connector_init() which takes care of setting up all the writeback-specific details on top of the normal functionality of drm_connector_init(). Writeback connectors have a WRITEBACK_FB_ID property, used to set the output framebuffer, and a WRITEBACK_PIXEL_FORMATS blob used to expose the supported writeback formats to userspace. When a framebuffer is attached to a writeback connector with the WRITEBACK_FB_ID property, it is used only once (for the commit in which it was included), and userspace can never read back the value of WRITEBACK_FB_ID. WRITEBACK_FB_ID can only be set if the connector is attached to a CRTC. Changes since v1: - Added drm_writeback.c + documentation - Added helper to initialize writeback connector in one go - Added core checks - Squashed into a single commit - Dropped the client cap - Writeback framebuffers are no longer persistent Changes since v2: Daniel Vetter: - Subclass drm_connector to drm_writeback_connector - Relax check to allow CRTC to be set without an FB - Add some writeback_ prefixes - Drop PIXEL_FORMATS_SIZE property, as it was unnecessary Gustavo Padovan: - Add drm_writeback_job to handle writeback signalling centrally Changes since v3: - Rebased - Rename PIXEL_FORMATS -> WRITEBACK_PIXEL_FORMATS Chances since v4: - Embed a drm_encoder inside the drm_writeback_connector to reduce the amount of boilerplate code required from the drivers that are using it. Changes since v5: - Added Rob Clark's atomic_commit() vfunc to connector helper funcs, so that writeback jobs are committed from atomic helpers - Updated create_writeback_properties() signature to return an error code rather than a boolean false for failure. - Free writeback job with the connector state rather than when doing the cleanup_work() Changes since v7: - fix extraneous use of out_fence that is only introduced in a subsequent patch. Changes since v8: - whitespace changes pull from subsequent patch Changes since v9: - Revert the v6 changes that free the writeback job in the connector state cleanup and return to doing it in the cleanup_work() function Signed-off-by: Brian Starkey [rebased and fixed conflicts] Signed-off-by: Mihail Atanassov [rebased and added atomic_commit() vfunc for writeback jobs] Signed-off-by: Rob Clark Signed-off-by: Liviu Dudau Reviewed-by: Eric Anholt Link: https://patchwork.freedesktop.org/patch/229037/ --- drivers/gpu/drm/drm_writeback.c | 245 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 245 insertions(+) create mode 100644 drivers/gpu/drm/drm_writeback.c (limited to 'drivers/gpu/drm/drm_writeback.c') diff --git a/drivers/gpu/drm/drm_writeback.c b/drivers/gpu/drm/drm_writeback.c new file mode 100644 index 000000000000..e5b8a4b79724 --- /dev/null +++ b/drivers/gpu/drm/drm_writeback.c @@ -0,0 +1,245 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * (C) COPYRIGHT 2016 ARM Limited. All rights reserved. + * Author: Brian Starkey + * + * This program is free software and is provided to you under the terms of the + * GNU General Public License version 2 as published by the Free Software + * Foundation, and any use by you of this program is subject to the terms + * of such GNU licence. + */ + +#include +#include +#include +#include +#include + +/** + * DOC: overview + * + * Writeback connectors are used to expose hardware which can write the output + * from a CRTC to a memory buffer. They are used and act similarly to other + * types of connectors, with some important differences: + * - Writeback connectors don't provide a way to output visually to the user. + * - Writeback connectors should always report as "disconnected" (so that + * clients which don't understand them will ignore them). + * - Writeback connectors don't have EDID. + * + * A framebuffer may only be attached to a writeback connector when the + * connector is attached to a CRTC. The WRITEBACK_FB_ID property which sets the + * framebuffer applies only to a single commit (see below). A framebuffer may + * not be attached while the CRTC is off. + * + * Writeback connectors have some additional properties, which userspace + * can use to query and control them: + * + * "WRITEBACK_FB_ID": + * Write-only object property storing a DRM_MODE_OBJECT_FB: it stores the + * framebuffer to be written by the writeback connector. This property is + * similar to the FB_ID property on planes, but will always read as zero + * and is not preserved across commits. + * Userspace must set this property to an output buffer every time it + * wishes the buffer to get filled. + * + * "WRITEBACK_PIXEL_FORMATS": + * Immutable blob property to store the supported pixel formats table. The + * data is an array of u32 DRM_FORMAT_* fourcc values. + * Userspace can use this blob to find out what pixel formats are supported + * by the connector's writeback engine. + */ + +static int create_writeback_properties(struct drm_device *dev) +{ + struct drm_property *prop; + + if (!dev->mode_config.writeback_fb_id_property) { + prop = drm_property_create_object(dev, DRM_MODE_PROP_ATOMIC, + "WRITEBACK_FB_ID", + DRM_MODE_OBJECT_FB); + if (!prop) + return -ENOMEM; + dev->mode_config.writeback_fb_id_property = prop; + } + + if (!dev->mode_config.writeback_pixel_formats_property) { + prop = drm_property_create(dev, DRM_MODE_PROP_BLOB | + DRM_MODE_PROP_ATOMIC | + DRM_MODE_PROP_IMMUTABLE, + "WRITEBACK_PIXEL_FORMATS", 0); + if (!prop) + return -ENOMEM; + dev->mode_config.writeback_pixel_formats_property = prop; + } + + return 0; +} + +static const struct drm_encoder_funcs drm_writeback_encoder_funcs = { + .destroy = drm_encoder_cleanup, +}; + +/** + * drm_writeback_connector_init - Initialize a writeback connector and its properties + * @dev: DRM device + * @wb_connector: Writeback connector to initialize + * @con_funcs: Connector funcs vtable + * @enc_helper_funcs: Encoder helper funcs vtable to be used by the internal encoder + * @formats: Array of supported pixel formats for the writeback engine + * @n_formats: Length of the formats array + * + * This function creates the writeback-connector-specific properties if they + * have not been already created, initializes the connector as + * type DRM_MODE_CONNECTOR_WRITEBACK, and correctly initializes the property + * values. It will also create an internal encoder associated with the + * drm_writeback_connector and set it to use the @enc_helper_funcs vtable for + * the encoder helper. + * + * Drivers should always use this function instead of drm_connector_init() to + * set up writeback connectors. + * + * Returns: 0 on success, or a negative error code + */ +int drm_writeback_connector_init(struct drm_device *dev, + struct drm_writeback_connector *wb_connector, + const struct drm_connector_funcs *con_funcs, + const struct drm_encoder_helper_funcs *enc_helper_funcs, + const u32 *formats, int n_formats) +{ + struct drm_property_blob *blob; + struct drm_connector *connector = &wb_connector->base; + struct drm_mode_config *config = &dev->mode_config; + int ret = create_writeback_properties(dev); + + if (ret != 0) + return ret; + + blob = drm_property_create_blob(dev, n_formats * sizeof(*formats), + formats); + if (IS_ERR(blob)) + return PTR_ERR(blob); + + drm_encoder_helper_add(&wb_connector->encoder, enc_helper_funcs); + ret = drm_encoder_init(dev, &wb_connector->encoder, + &drm_writeback_encoder_funcs, + DRM_MODE_ENCODER_VIRTUAL, NULL); + if (ret) + goto fail; + + connector->interlace_allowed = 0; + + ret = drm_connector_init(dev, connector, con_funcs, + DRM_MODE_CONNECTOR_WRITEBACK); + if (ret) + goto connector_fail; + + ret = drm_mode_connector_attach_encoder(connector, + &wb_connector->encoder); + if (ret) + goto attach_fail; + + INIT_LIST_HEAD(&wb_connector->job_queue); + spin_lock_init(&wb_connector->job_lock); + + drm_object_attach_property(&connector->base, + config->writeback_fb_id_property, 0); + + drm_object_attach_property(&connector->base, + config->writeback_pixel_formats_property, + blob->base.id); + wb_connector->pixel_formats_blob_ptr = blob; + + return 0; + +attach_fail: + drm_connector_cleanup(connector); +connector_fail: + drm_encoder_cleanup(&wb_connector->encoder); +fail: + drm_property_blob_put(blob); + return ret; +} +EXPORT_SYMBOL(drm_writeback_connector_init); + +/** + * drm_writeback_queue_job - Queue a writeback job for later signalling + * @wb_connector: The writeback connector to queue a job on + * @job: The job to queue + * + * This function adds a job to the job_queue for a writeback connector. It + * should be considered to take ownership of the writeback job, and so any other + * references to the job must be cleared after calling this function. + * + * Drivers must ensure that for a given writeback connector, jobs are queued in + * exactly the same order as they will be completed by the hardware (and + * signaled via drm_writeback_signal_completion). + * + * For every call to drm_writeback_queue_job() there must be exactly one call to + * drm_writeback_signal_completion() + * + * See also: drm_writeback_signal_completion() + */ +void drm_writeback_queue_job(struct drm_writeback_connector *wb_connector, + struct drm_writeback_job *job) +{ + unsigned long flags; + + spin_lock_irqsave(&wb_connector->job_lock, flags); + list_add_tail(&job->list_entry, &wb_connector->job_queue); + spin_unlock_irqrestore(&wb_connector->job_lock, flags); +} +EXPORT_SYMBOL(drm_writeback_queue_job); + +/* + * @cleanup_work: deferred cleanup of a writeback job + * + * The job cannot be cleaned up directly in drm_writeback_signal_completion, + * because it may be called in interrupt context. Dropping the framebuffer + * reference can sleep, and so the cleanup is deferred to a workqueue. + */ +static void cleanup_work(struct work_struct *work) +{ + struct drm_writeback_job *job = container_of(work, + struct drm_writeback_job, + cleanup_work); + drm_framebuffer_put(job->fb); + kfree(job); +} + + +/** + * drm_writeback_signal_completion - Signal the completion of a writeback job + * @wb_connector: The writeback connector whose job is complete + * + * Drivers should call this to signal the completion of a previously queued + * writeback job. It should be called as soon as possible after the hardware + * has finished writing, and may be called from interrupt context. + * It is the driver's responsibility to ensure that for a given connector, the + * hardware completes writeback jobs in the same order as they are queued. + * + * Unless the driver is holding its own reference to the framebuffer, it must + * not be accessed after calling this function. + * + * See also: drm_writeback_queue_job() + */ +void +drm_writeback_signal_completion(struct drm_writeback_connector *wb_connector) +{ + unsigned long flags; + struct drm_writeback_job *job; + + spin_lock_irqsave(&wb_connector->job_lock, flags); + job = list_first_entry_or_null(&wb_connector->job_queue, + struct drm_writeback_job, + list_entry); + if (job) + list_del(&job->list_entry); + spin_unlock_irqrestore(&wb_connector->job_lock, flags); + + if (WARN_ON(!job)) + return; + + INIT_WORK(&job->cleanup_work, cleanup_work); + queue_work(system_long_wq, &job->cleanup_work); +} +EXPORT_SYMBOL(drm_writeback_signal_completion); -- cgit v1.2.2 From b13cc8dd588434e2aec781e6d12224e4c408ac18 Mon Sep 17 00:00:00 2001 From: Brian Starkey Date: Wed, 29 Mar 2017 17:42:33 +0100 Subject: drm: writeback: Add out-fences for writeback connectors Add the WRITEBACK_OUT_FENCE_PTR property to writeback connectors, to enable userspace to get a fence which will signal once the writeback is complete. It is not allowed to request an out-fence without a framebuffer attached to the connector. A timeline is added to drm_writeback_connector for use by the writeback out-fences. In the case of a commit failure or DRM_MODE_ATOMIC_TEST_ONLY, the fence is set to -1. Changes from v2: - Rebase onto Gustavo Padovan's v9 explicit sync series - Change out_fence_ptr type to s32 __user * - Set *out_fence_ptr to -1 in drm_atomic_connector_set_property - Store fence in drm_writeback_job Gustavo Padovan: - Move out_fence_ptr out of connector_state - Signal fence from drm_writeback_signal_completion instead of in driver directly Changes from v3: - Rebase onto commit 7e9081c5aac7 ("drm/fence: fix memory overwrite when setting out_fence fd") (change out_fence_ptr to s32 __user *, for real this time.) - Update documentation around WRITEBACK_OUT_FENCE_PTR Signed-off-by: Brian Starkey [rebased and fixed conflicts] Signed-off-by: Mihail Atanassov Signed-off-by: Liviu Dudau Reviewed-by: Eric Anholt Reviewed-by: Sean Paul Link: https://patchwork.freedesktop.org/patch/229036/ --- drivers/gpu/drm/drm_writeback.c | 109 +++++++++++++++++++++++++++++++++++++++- 1 file changed, 107 insertions(+), 2 deletions(-) (limited to 'drivers/gpu/drm/drm_writeback.c') diff --git a/drivers/gpu/drm/drm_writeback.c b/drivers/gpu/drm/drm_writeback.c index e5b8a4b79724..827395071f0b 100644 --- a/drivers/gpu/drm/drm_writeback.c +++ b/drivers/gpu/drm/drm_writeback.c @@ -14,6 +14,7 @@ #include #include #include +#include /** * DOC: overview @@ -31,6 +32,16 @@ * framebuffer applies only to a single commit (see below). A framebuffer may * not be attached while the CRTC is off. * + * Unlike with planes, when a writeback framebuffer is removed by userspace DRM + * makes no attempt to remove it from active use by the connector. This is + * because no method is provided to abort a writeback operation, and in any + * case making a new commit whilst a writeback is ongoing is undefined (see + * WRITEBACK_OUT_FENCE_PTR below). As soon as the current writeback is finished, + * the framebuffer will automatically no longer be in active use. As it will + * also have already been removed from the framebuffer list, there will be no + * way for any userspace application to retrieve a reference to it in the + * intervening period. + * * Writeback connectors have some additional properties, which userspace * can use to query and control them: * @@ -47,8 +58,54 @@ * data is an array of u32 DRM_FORMAT_* fourcc values. * Userspace can use this blob to find out what pixel formats are supported * by the connector's writeback engine. + * + * "WRITEBACK_OUT_FENCE_PTR": + * Userspace can use this property to provide a pointer for the kernel to + * fill with a sync_file file descriptor, which will signal once the + * writeback is finished. The value should be the address of a 32-bit + * signed integer, cast to a u64. + * Userspace should wait for this fence to signal before making another + * commit affecting any of the same CRTCs, Planes or Connectors. + * **Failure to do so will result in undefined behaviour.** + * For this reason it is strongly recommended that all userspace + * applications making use of writeback connectors *always* retrieve an + * out-fence for the commit and use it appropriately. + * From userspace, this property will always read as zero. */ +#define fence_to_wb_connector(x) container_of(x->lock, \ + struct drm_writeback_connector, \ + fence_lock) + +static const char *drm_writeback_fence_get_driver_name(struct dma_fence *fence) +{ + struct drm_writeback_connector *wb_connector = + fence_to_wb_connector(fence); + + return wb_connector->base.dev->driver->name; +} + +static const char * +drm_writeback_fence_get_timeline_name(struct dma_fence *fence) +{ + struct drm_writeback_connector *wb_connector = + fence_to_wb_connector(fence); + + return wb_connector->timeline_name; +} + +static bool drm_writeback_fence_enable_signaling(struct dma_fence *fence) +{ + return true; +} + +static const struct dma_fence_ops drm_writeback_fence_ops = { + .get_driver_name = drm_writeback_fence_get_driver_name, + .get_timeline_name = drm_writeback_fence_get_timeline_name, + .enable_signaling = drm_writeback_fence_enable_signaling, + .wait = dma_fence_default_wait, +}; + static int create_writeback_properties(struct drm_device *dev) { struct drm_property *prop; @@ -72,6 +129,15 @@ static int create_writeback_properties(struct drm_device *dev) dev->mode_config.writeback_pixel_formats_property = prop; } + if (!dev->mode_config.writeback_out_fence_ptr_property) { + prop = drm_property_create_range(dev, DRM_MODE_PROP_ATOMIC, + "WRITEBACK_OUT_FENCE_PTR", 0, + U64_MAX); + if (!prop) + return -ENOMEM; + dev->mode_config.writeback_out_fence_ptr_property = prop; + } + return 0; } @@ -141,6 +207,15 @@ int drm_writeback_connector_init(struct drm_device *dev, INIT_LIST_HEAD(&wb_connector->job_queue); spin_lock_init(&wb_connector->job_lock); + wb_connector->fence_context = dma_fence_context_alloc(1); + spin_lock_init(&wb_connector->fence_lock); + snprintf(wb_connector->timeline_name, + sizeof(wb_connector->timeline_name), + "CONNECTOR:%d-%s", connector->base.id, connector->name); + + drm_object_attach_property(&connector->base, + config->writeback_out_fence_ptr_property, 0); + drm_object_attach_property(&connector->base, config->writeback_fb_id_property, 0); @@ -210,6 +285,7 @@ static void cleanup_work(struct work_struct *work) /** * drm_writeback_signal_completion - Signal the completion of a writeback job * @wb_connector: The writeback connector whose job is complete + * @status: Status code to set in the writeback out_fence (0 for success) * * Drivers should call this to signal the completion of a previously queued * writeback job. It should be called as soon as possible after the hardware @@ -223,7 +299,8 @@ static void cleanup_work(struct work_struct *work) * See also: drm_writeback_queue_job() */ void -drm_writeback_signal_completion(struct drm_writeback_connector *wb_connector) +drm_writeback_signal_completion(struct drm_writeback_connector *wb_connector, + int status) { unsigned long flags; struct drm_writeback_job *job; @@ -232,8 +309,15 @@ drm_writeback_signal_completion(struct drm_writeback_connector *wb_connector) job = list_first_entry_or_null(&wb_connector->job_queue, struct drm_writeback_job, list_entry); - if (job) + if (job) { list_del(&job->list_entry); + if (job->out_fence) { + if (status) + dma_fence_set_error(job->out_fence, status); + dma_fence_signal(job->out_fence); + dma_fence_put(job->out_fence); + } + } spin_unlock_irqrestore(&wb_connector->job_lock, flags); if (WARN_ON(!job)) @@ -243,3 +327,24 @@ drm_writeback_signal_completion(struct drm_writeback_connector *wb_connector) queue_work(system_long_wq, &job->cleanup_work); } EXPORT_SYMBOL(drm_writeback_signal_completion); + +struct dma_fence * +drm_writeback_get_out_fence(struct drm_writeback_connector *wb_connector) +{ + struct dma_fence *fence; + + if (WARN_ON(wb_connector->base.connector_type != + DRM_MODE_CONNECTOR_WRITEBACK)) + return NULL; + + fence = kzalloc(sizeof(*fence), GFP_KERNEL); + if (!fence) + return NULL; + + dma_fence_init(fence, &drm_writeback_fence_ops, + &wb_connector->fence_lock, wb_connector->fence_context, + ++wb_connector->fence_seqno); + + return fence; +} +EXPORT_SYMBOL(drm_writeback_get_out_fence); -- cgit v1.2.2 From 73915b2b1f2581cbce5a511550c2cac2e2b42595 Mon Sep 17 00:00:00 2001 From: Boris Brezillon Date: Tue, 3 Jul 2018 19:40:46 +0200 Subject: drm/writeback: Fix the "overview" section of the doc Fix the bullet list declaration in the overview section. Signed-off-by: Boris Brezillon Reported-by: Daniel Vetter Fixes: 935774cd71fe ("drm: Add writeback connector type") Acked-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20180703174046.22396-1-boris.brezillon@bootlin.com --- drivers/gpu/drm/drm_writeback.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) (limited to 'drivers/gpu/drm/drm_writeback.c') diff --git a/drivers/gpu/drm/drm_writeback.c b/drivers/gpu/drm/drm_writeback.c index 827395071f0b..69e7a63cfcc3 100644 --- a/drivers/gpu/drm/drm_writeback.c +++ b/drivers/gpu/drm/drm_writeback.c @@ -22,10 +22,13 @@ * Writeback connectors are used to expose hardware which can write the output * from a CRTC to a memory buffer. They are used and act similarly to other * types of connectors, with some important differences: - * - Writeback connectors don't provide a way to output visually to the user. - * - Writeback connectors should always report as "disconnected" (so that - * clients which don't understand them will ignore them). - * - Writeback connectors don't have EDID. + * + * * Writeback connectors don't provide a way to output visually to the user. + * + * * Writeback connectors should always report as "disconnected" (so that + * clients which don't understand them will ignore them). + * + * * Writeback connectors don't have EDID. * * A framebuffer may only be attached to a writeback connector when the * connector is attached to a CRTC. The WRITEBACK_FB_ID property which sets the -- cgit v1.2.2 From cde4c44d8769c1be16074c097592c46c7d64092b Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Mon, 9 Jul 2018 10:40:07 +0200 Subject: drm: drop _mode_ from drm_mode_connector_attach_encoder Again to align with the usual prefix of just drm_connector_. Again done with sed + manual fixup for indent issues. Reviewed-by: Sean Paul Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20180709084016.23750-7-daniel.vetter@ffwll.ch --- drivers/gpu/drm/drm_writeback.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/gpu/drm/drm_writeback.c') diff --git a/drivers/gpu/drm/drm_writeback.c b/drivers/gpu/drm/drm_writeback.c index 69e7a63cfcc3..169746f6b567 100644 --- a/drivers/gpu/drm/drm_writeback.c +++ b/drivers/gpu/drm/drm_writeback.c @@ -202,7 +202,7 @@ int drm_writeback_connector_init(struct drm_device *dev, if (ret) goto connector_fail; - ret = drm_mode_connector_attach_encoder(connector, + ret = drm_connector_attach_encoder(connector, &wb_connector->encoder); if (ret) goto attach_fail; -- cgit v1.2.2 From 71a5cb3eb758b5b3735709c7fca577522eda43d4 Mon Sep 17 00:00:00 2001 From: Alexandru Gheorghe Date: Fri, 13 Jul 2018 16:10:58 +0100 Subject: drm: writeback: Fix doc that says connector should be disconnected During iteration process one of the proposed mechanism for not breaking existing userspace was to report writeback connectors as disconnected, however the final version used DRM_CLIENT_CAP_WRITEBACK_CONNECTORS for that purpose. Change-Id: I2319d099f7669094c8530f1521abdbca08e76486 Signed-off-by: Alexandru Gheorghe Reviewed-by: Sean Paul Acked-by: Liviu Dudau Link: https://patchwork.freedesktop.org/patch/238399/ --- drivers/gpu/drm/drm_writeback.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/gpu/drm/drm_writeback.c') diff --git a/drivers/gpu/drm/drm_writeback.c b/drivers/gpu/drm/drm_writeback.c index 169746f6b567..c20e6fe00cb3 100644 --- a/drivers/gpu/drm/drm_writeback.c +++ b/drivers/gpu/drm/drm_writeback.c @@ -25,8 +25,8 @@ * * * Writeback connectors don't provide a way to output visually to the user. * - * * Writeback connectors should always report as "disconnected" (so that - * clients which don't understand them will ignore them). + * * Writeback connectors are visible to userspace only when the client sets + * DRM_CLIENT_CAP_WRITEBACK_CONNECTORS. * * * Writeback connectors don't have EDID. * -- cgit v1.2.2