Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S943018AbcJ0Ozn (ORCPT ); Thu, 27 Oct 2016 10:55:43 -0400 Received: from foss.arm.com ([217.140.101.70]:38782 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936546AbcJ0Ozi (ORCPT ); Thu, 27 Oct 2016 10:55:38 -0400 Date: Thu, 27 Oct 2016 11:07:37 +0100 From: Brian Starkey To: Gustavo Padovan , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org Subject: Re: [RFC PATCH v2 8/9] drm: writeback: Add out-fences for writeback connectors Message-ID: <20161027100736.GB18708@e106950-lin.cambridge.arm.com> References: <1477472108-27222-1-git-send-email-brian.starkey@arm.com> <1477472108-27222-9-git-send-email-brian.starkey@arm.com> <20161026214029.GG12629@joana> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20161026214029.GG12629@joana> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 13891 Lines: 379 Hi Gustavo, On Wed, Oct 26, 2016 at 07:40:29PM -0200, Gustavo Padovan wrote: >2016-10-26 Brian Starkey : > >> Add the OUT_FENCE_PTR property to writeback connectors, to enable >> userspace to get a fence which will signal once the writeback is >> complete. >> >> A timeline is added to drm_connector for use by the writeback >> out-fences. It is up to drivers to check for a fence in the >> connector_state and signal the it appropriately when their writeback has >> finished. >> >> It is not allowed to request an out-fence without a framebuffer attached >> to the connector. >> >> Signed-off-by: Brian Starkey >> --- >> drivers/gpu/drm/drm_atomic.c | 60 +++++++++++++++++++++++--- >> drivers/gpu/drm/drm_atomic_helper.c | 5 ++- >> drivers/gpu/drm/drm_writeback.c | 80 +++++++++++++++++++++++++++++++++++ >> include/drm/drm_connector.h | 14 ++++++ >> include/drm/drm_writeback.h | 2 + >> 5 files changed, 155 insertions(+), 6 deletions(-) >> >> diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c >> index 3f8fc97..061ea13 100644 >> --- a/drivers/gpu/drm/drm_atomic.c >> +++ b/drivers/gpu/drm/drm_atomic.c >> @@ -30,6 +30,7 @@ >> #include >> #include >> #include >> +#include >> #include >> >> #include "drm_crtc_internal.h" >> @@ -646,6 +647,12 @@ static int drm_atomic_connector_check(struct drm_connector *connector, >> return -EINVAL; >> } >> >> + if (state->out_fence && !state->fb) { >> + DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] requesting out-fence without framebuffer\n", >> + connector->base.id, connector->name); >> + return -EINVAL; >> + } >> + >> return 0; >> } >> >> @@ -1047,6 +1054,8 @@ int drm_atomic_connector_set_property(struct drm_connector *connector, >> drm_atomic_set_fb_for_connector(state, fb); >> if (fb) >> drm_framebuffer_unreference(fb); >> + } else if (property == config->prop_out_fence_ptr) { >> + state->out_fence_ptr = u64_to_user_ptr(val); > >We need to move this out of the conn_state. For my v6 on CRTC out fences >I added drm_atomic_set_out_fence_for_crtc() and >drm_atomic_get_out_fence_for_crtc(). See padovan/fences. > Yep, will do. I was expecting this to change >> } else if (connector->funcs->atomic_set_property) { >> return connector->funcs->atomic_set_property(connector, >> state, property, val); >> @@ -1088,6 +1097,8 @@ drm_atomic_connector_get_property(struct drm_connector *connector, >> } else if (property == config->writeback_fb_id_property) { >> /* Writeback framebuffer is one-shot, write and forget */ >> *val = 0; >> + } else if (property == config->prop_out_fence_ptr) { >> + *val = 0; >> } else if (connector->funcs->atomic_get_property) { >> return connector->funcs->atomic_get_property(connector, >> state, property, val); >> @@ -1736,6 +1747,39 @@ static int setup_out_fence(struct drm_out_fence_state *fence_state, >> return 0; >> } >> >> +static int setup_connector_out_fences(struct drm_atomic_state *state, >> + struct drm_out_fence_state *fence_state, >> + int *fence_idx) >> +{ >> + struct drm_connector *conn; >> + struct drm_connector_state *conn_state; >> + int i, ret; >> + >> + for_each_connector_in_state(state, conn, conn_state, i) { >> + struct fence *fence; >> + >> + if (!conn_state->out_fence_ptr) >> + continue; >> + >> + fence = drm_writeback_get_out_fence(conn, conn_state); >> + if (!fence) >> + return -ENOMEM; >> + >> + ret = setup_out_fence(&fence_state[(*fence_idx)++], >> + conn_state->out_fence_ptr, >> + fence); >> + if (ret) { >> + fence_put(fence); >> + return ret; >> + } >> + >> + /* One-time usage only */ >> + conn_state->out_fence_ptr = NULL; >> + } >> + >> + return 0; >> +} >> + >> int drm_mode_atomic_ioctl(struct drm_device *dev, >> void *data, struct drm_file *file_priv) >> { >> @@ -1868,8 +1912,8 @@ retry: >> drm_mode_object_unreference(obj); >> } >> >> - fence_state = kcalloc(dev->mode_config.num_crtc, sizeof(*fence_state), >> - GFP_KERNEL); >> + fence_state = kcalloc(dev->mode_config.num_crtc + state->num_connector, >> + sizeof(*fence_state), GFP_KERNEL); >> if (!fence_state) { >> ret = -ENOMEM; >> goto out; >> @@ -1929,10 +1973,16 @@ retry: >> * Below we call drm_atomic_state_free for it. >> */ >> ret = drm_atomic_check_only(state); >> - } else if (arg->flags & DRM_MODE_ATOMIC_NONBLOCK) { >> - ret = drm_atomic_nonblocking_commit(state); >> } else { >> - ret = drm_atomic_commit(state); >> + ret = setup_connector_out_fences(state, fence_state, >> + &fence_idx); >> + if (ret) >> + goto out; > >I'd do this before this block. At the DRM_MODE_ATOMIC_TEST_ONLY or we >check or we commit. Moreover you should check if out_fences >are not set with TEST_ONLY. > I don't quite follow the second sentence; you mean you'd rather I was finished setting things up before the TEST_ONLY check? That sounds OK. For TEST_ONLY I actually think we shouldn't reject commits with OUT_FENCE_PTRs and TEST_ONLY. I thought the idea of TEST_ONLY was for userspace to build a commit, then see if it can work, then commit it for real. By rejecting TEST_ONLY + OUT_FENCE_PTRs you're saying userspace can never test what it actually intends to commit. It has to test, then add the out-fences, then commit and hope for the best. How about always setting the out-fences to -1 for TEST_ONLY? Thanks for the review, -Brian >> + >> + if (arg->flags & DRM_MODE_ATOMIC_NONBLOCK) >> + ret = drm_atomic_nonblocking_commit(state); >> + else >> + ret = drm_atomic_commit(state); >> } >> >> if (!ret) >> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c >> index bba8672..88da299 100644 >> --- a/drivers/gpu/drm/drm_atomic_helper.c >> +++ b/drivers/gpu/drm/drm_atomic_helper.c >> @@ -3234,8 +3234,9 @@ __drm_atomic_helper_connector_duplicate_state(struct drm_connector *connector, >> if (state->crtc) >> drm_connector_reference(connector); >> >> - /* Don't copy over framebuffers, they are used only once */ >> + /* Don't copy over framebuffers or fences, they are used only once */ >> state->fb = NULL; >> + state->out_fence = NULL; >> } >> EXPORT_SYMBOL(__drm_atomic_helper_connector_duplicate_state); >> >> @@ -3365,6 +3366,8 @@ __drm_atomic_helper_connector_destroy_state(struct drm_connector_state *state) >> drm_connector_unreference(state->connector); >> if (state->fb) >> drm_framebuffer_unreference(state->fb); >> + >> + fence_put(state->out_fence); >> } >> EXPORT_SYMBOL(__drm_atomic_helper_connector_destroy_state); >> >> diff --git a/drivers/gpu/drm/drm_writeback.c b/drivers/gpu/drm/drm_writeback.c >> index 5a6e0ad..4a6ef30 100644 >> --- a/drivers/gpu/drm/drm_writeback.c >> +++ b/drivers/gpu/drm/drm_writeback.c >> @@ -11,6 +11,7 @@ >> #include >> #include >> #include >> +#include >> >> /** >> * DOC: overview >> @@ -32,6 +33,16 @@ >> * explicitly cleared in order to make a subsequent commit which doesn't use >> * writeback. >> * >> + * 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 >> + * 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 several additional properties, which userspace >> * can use to query and control them: >> * >> @@ -52,8 +63,48 @@ >> * "PIXEL_FORMATS_SIZE": >> * Immutable unsigned range property storing the number of entries in the >> * PIXEL_FORMATS array. >> + * >> + * "OUT_FENCE_PTR": >> + * Userspace can provide the address of a 64-bit integer in this property, >> + * which will be filled with a sync_file file descriptor by the kernel. >> + * The sync_file will signal when the associated writeback has finished. >> + * 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_connector(x) container_of(x->lock, struct drm_connector, fence_lock) >> + >> +static const char *drm_writeback_fence_get_driver_name(struct fence *fence) >> +{ >> + struct drm_connector *connector = fence_to_connector(fence); >> + >> + return connector->dev->driver->name; >> +} >> + >> +static const char *drm_writeback_fence_get_timeline_name(struct fence *fence) >> +{ >> + struct drm_connector *connector = fence_to_connector(fence); >> + >> + return connector->timeline_name; >> +} >> + >> +static bool drm_writeback_fence_enable_signaling(struct fence *fence) >> +{ >> + return true; >> +} >> + >> +static const struct 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 = fence_default_wait, >> +}; >> + >> /** >> * create_writeback_properties - Create writeback connector-specific properties >> * @dev: DRM device >> @@ -136,6 +187,14 @@ int drm_writeback_connector_init(struct drm_device *dev, >> if (ret) >> goto fail; >> >> + connector->fence_context = fence_context_alloc(1); >> + spin_lock_init(&connector->fence_lock); >> + snprintf(connector->timeline_name, sizeof(connector->timeline_name), >> + "CONNECTOR:%d", connector->base.id); >> + >> + drm_object_attach_property(&connector->base, >> + config->prop_out_fence_ptr, 0); >> + >> drm_object_attach_property(&connector->base, >> config->writeback_fb_id_property, 0); >> >> @@ -155,3 +214,24 @@ fail: >> return ret; >> } >> EXPORT_SYMBOL(drm_writeback_connector_init); >> + >> +struct fence *drm_writeback_get_out_fence(struct drm_connector *connector, >> + struct drm_connector_state *conn_state) >> +{ >> + struct fence *fence; >> + >> + if (WARN_ON(connector->connector_type != DRM_MODE_CONNECTOR_WRITEBACK)) >> + return NULL; >> + >> + fence = kzalloc(sizeof(*fence), GFP_KERNEL); >> + if (!fence) >> + return NULL; >> + >> + fence_init(fence, &drm_writeback_fence_ops, &connector->fence_lock, >> + connector->fence_context, ++connector->fence_seqno); >> + >> + conn_state->out_fence = fence_get(fence); >> + >> + return fence; >> +} >> +EXPORT_SYMBOL(drm_writeback_get_out_fence); >> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h >> index a5e3778..7d40537 100644 >> --- a/include/drm/drm_connector.h >> +++ b/include/drm/drm_connector.h >> @@ -199,6 +199,7 @@ int drm_display_info_set_bus_formats(struct drm_display_info *info, >> * @best_encoder: can be used by helpers and drivers to select the encoder >> * @state: backpointer to global drm_atomic_state >> * @fb: Writeback framebuffer, for DRM_MODE_CONNECTOR_WRITEBACK >> + * @out_fence: Fence which will clear when the framebuffer write has finished >> */ >> struct drm_connector_state { >> struct drm_connector *connector; >> @@ -216,6 +217,9 @@ struct drm_connector_state { >> struct drm_atomic_state *state; >> >> struct drm_framebuffer *fb; /* do not write directly, use drm_atomic_set_fb_for_connector() */ >> + >> + struct fence *out_fence; >> + u64 __user *out_fence_ptr; >> }; >> >> /** >> @@ -546,6 +550,10 @@ struct drm_cmdline_mode { >> * @tile_v_loc: vertical location of this tile >> * @tile_h_size: horizontal size of this tile. >> * @tile_v_size: vertical size of this tile. >> + * @fence_context: context for fence signalling >> + * @fence_lock: fence lock for the fence context >> + * @fence_seqno: seqno variable to create fences >> + * @timeline_name: fence timeline name >> * >> * Each connector may be connected to one or more CRTCs, or may be clonable by >> * another connector if they can share a CRTC. Each connector also has a specific >> @@ -694,6 +702,12 @@ struct drm_connector { >> uint8_t num_h_tile, num_v_tile; >> uint8_t tile_h_loc, tile_v_loc; >> uint16_t tile_h_size, tile_v_size; >> + >> + /* fence timelines info for DRM out-fences */ >> + unsigned int fence_context; >> + spinlock_t fence_lock; >> + unsigned long fence_seqno; >> + char timeline_name[32]; >> }; >> >> #define obj_to_connector(x) container_of(x, struct drm_connector, base) >> diff --git a/include/drm/drm_writeback.h b/include/drm/drm_writeback.h >> index afdc2742..01f33bc 100644 >> --- a/include/drm/drm_writeback.h >> +++ b/include/drm/drm_writeback.h >> @@ -16,4 +16,6 @@ int drm_writeback_connector_init(struct drm_device *dev, >> const struct drm_connector_funcs *funcs, >> u32 *formats, int n_formats); >> >> +struct fence *drm_writeback_get_out_fence(struct drm_connector *connector, >> + struct drm_connector_state *conn_state); >> #endif >> -- >> 1.7.9.5 >> >> _______________________________________________ >> dri-devel mailing list >> dri-devel@lists.freedesktop.org >> https://lists.freedesktop.org/mailman/listinfo/dri-devel >