linux-stable/drivers/gpu/drm/drm_encoder.c

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/*
* Copyright (c) 2016 Intel Corporation
*
* Permission to use, copy, modify, distribute, and sell this software and its
* documentation for any purpose is hereby granted without fee, provided that
* the above copyright notice appear in all copies and that both that copyright
* notice and this permission notice appear in supporting documentation, and
* that the name of the copyright holders not be used in advertising or
* publicity pertaining to distribution of the software without specific,
* written prior permission. The copyright holders make no representations
* about the suitability of this software for any purpose. It is provided "as
* is" without express or implied warranty.
*
* THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
* EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
* DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
* TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
* OF THIS SOFTWARE.
*/
#include <linux/export.h>
#include <drm/drmP.h>
#include <drm/drm_encoder.h>
#include "drm_crtc_internal.h"
/**
* DOC: overview
*
* Encoders represent the connecting element between the CRTC (as the overall
* pixel pipeline, represented by &struct drm_crtc) and the connectors (as the
* generic sink entity, represented by &struct drm_connector). An encoder takes
* pixel data from a CRTC and converts it to a format suitable for any attached
* connector. Encoders are objects exposed to userspace, originally to allow
* userspace to infer cloning and connector/CRTC restrictions. Unfortunately
* almost all drivers get this wrong, making the uabi pretty much useless. On
* top of that the exposed restrictions are too simple for today's hardware, and
* the recommended way to infer restrictions is by using the
* DRM_MODE_ATOMIC_TEST_ONLY flag for the atomic IOCTL.
*
* Otherwise encoders aren't used in the uapi at all (any modeset request from
* userspace directly connects a connector with a CRTC), drivers are therefore
* free to use them however they wish. Modeset helper libraries make strong use
* of encoders to facilitate code sharing. But for more complex settings it is
* usually better to move shared code into a separate &drm_bridge. Compared to
* encoders, bridges also have the benefit of being purely an internal
* abstraction since they are not exposed to userspace at all.
*
* Encoders are initialized with drm_encoder_init() and cleaned up using
* drm_encoder_cleanup().
*/
static const struct drm_prop_enum_list drm_encoder_enum_list[] = {
{ DRM_MODE_ENCODER_NONE, "None" },
{ DRM_MODE_ENCODER_DAC, "DAC" },
{ DRM_MODE_ENCODER_TMDS, "TMDS" },
{ DRM_MODE_ENCODER_LVDS, "LVDS" },
{ DRM_MODE_ENCODER_TVDAC, "TV" },
{ DRM_MODE_ENCODER_VIRTUAL, "Virtual" },
{ DRM_MODE_ENCODER_DSI, "DSI" },
{ DRM_MODE_ENCODER_DPMST, "DP MST" },
{ DRM_MODE_ENCODER_DPI, "DPI" },
};
int drm_encoder_register_all(struct drm_device *dev)
{
struct drm_encoder *encoder;
int ret = 0;
drm_for_each_encoder(encoder, dev) {
if (encoder->funcs->late_register)
ret = encoder->funcs->late_register(encoder);
if (ret)
return ret;
}
return 0;
}
void drm_encoder_unregister_all(struct drm_device *dev)
{
struct drm_encoder *encoder;
drm_for_each_encoder(encoder, dev) {
if (encoder->funcs->early_unregister)
encoder->funcs->early_unregister(encoder);
}
}
/**
* drm_encoder_init - Init a preallocated encoder
* @dev: drm device
* @encoder: the encoder to init
* @funcs: callbacks for this encoder
* @encoder_type: user visible type of the encoder
* @name: printf style format string for the encoder name, or NULL for default name
*
* Initialises a preallocated encoder. Encoder should be subclassed as part of
* driver encoder objects. At driver unload time drm_encoder_cleanup() should be
* called from the driver's &drm_encoder_funcs.destroy hook.
*
* Returns:
* Zero on success, error code on failure.
*/
int drm_encoder_init(struct drm_device *dev,
struct drm_encoder *encoder,
const struct drm_encoder_funcs *funcs,
int encoder_type, const char *name, ...)
{
int ret;
ret = drm_mode_object_add(dev, &encoder->base, DRM_MODE_OBJECT_ENCODER);
if (ret)
return ret;
encoder->dev = dev;
encoder->encoder_type = encoder_type;
encoder->funcs = funcs;
if (name) {
va_list ap;
va_start(ap, name);
encoder->name = kvasprintf(GFP_KERNEL, name, ap);
va_end(ap);
} else {
encoder->name = kasprintf(GFP_KERNEL, "%s-%d",
drm_encoder_enum_list[encoder_type].name,
encoder->base.id);
}
if (!encoder->name) {
ret = -ENOMEM;
goto out_put;
}
list_add_tail(&encoder->head, &dev->mode_config.encoder_list);
encoder->index = dev->mode_config.num_encoder++;
out_put:
if (ret)
drm_mode_object_unregister(dev, &encoder->base);
return ret;
}
EXPORT_SYMBOL(drm_encoder_init);
/**
* drm_encoder_cleanup - cleans up an initialised encoder
* @encoder: encoder to cleanup
*
* Cleans up the encoder but doesn't free the object.
*/
void drm_encoder_cleanup(struct drm_encoder *encoder)
{
struct drm_device *dev = encoder->dev;
/* Note that the encoder_list is considered to be static; should we
* remove the drm_encoder at runtime we would have to decrement all
* the indices on the drm_encoder after us in the encoder_list.
*/
if (encoder->bridge) {
struct drm_bridge *bridge = encoder->bridge;
struct drm_bridge *next;
while (bridge) {
next = bridge->next;
drm_bridge_detach(bridge);
bridge = next;
}
}
drm_mode_object_unregister(dev, &encoder->base);
kfree(encoder->name);
list_del(&encoder->head);
dev->mode_config.num_encoder--;
memset(encoder, 0, sizeof(*encoder));
}
EXPORT_SYMBOL(drm_encoder_cleanup);
static struct drm_crtc *drm_encoder_get_crtc(struct drm_encoder *encoder)
{
struct drm_connector *connector;
struct drm_device *dev = encoder->dev;
bool uses_atomic = false;
drm: locking&new iterators for connector_list The requirements for connector_list locking are a bit tricky: - We need to be able to jump over zombie conectors (i.e. with refcount == 0, but not yet removed from the list). If instead we require that there's no zombies on the list then the final kref_put must happen under the list protection lock, which means that locking context leaks all over the place. Not pretty - better to deal with zombies and wrap the locking just around the list_del in the destructor. - When we walk the list we must _not_ hold the connector list lock. We walk the connector list at an absolutely massive amounts of places, if all those places can't ever call drm_connector_unreference the code would get unecessarily complicated. - connector_list needs it own lock, again too many places that walk it that we could reuse e.g. mode_config.mutex without resulting in inversions. - Lots of code uses these loops to look-up a connector, i.e. they want to be able to call drm_connector_reference. But on the other hand we want connectors to stay on that list until they're dead (i.e. connector_list can't hold a full reference), which means despite the "can't hold lock for the loop body" rule we need to make sure a connector doesn't suddenly become a zombie. At first Dave&I discussed various horror-show approaches using srcu, but turns out it's fairly easy: - For the loop body we always hold an additional reference to the current connector. That means it can't zombify, and it also means it'll stay on the list, which means we can use it as our iterator to find the next connector. - When we try to find the next connector we only have to jump over zombies. To make sure we don't chase bad pointers that entire loop is protected with the new connect_list_lock spinlock. And because we know that we're starting out with a non-zombie (need to drop our reference for the old connector only after we have our new one), we're guranteed to still be on the connector_list and either find the next non-zombie or complete the iteration. - Only downside is that we need to make sure that the temporary reference for the loop body doesn't leak. iter_get/put() functions + lockdep make sure that's the case. - To avoid a flag day the new iterator macro has an _iter postfix. We can rename it back once all the users of the unsafe version are gone (there's about 100 list walkers for the connector_list). For now this patch only converts all the list walking in the core, leaving helpers and drivers for later patches. The nice thing is that we can now finally remove 2 FIXME comments from the register/unregister functions. v2: - use irqsafe spinlocks, so that we can use this in drm_state_dump too. - nuke drm_modeset_lock_all from drm_connector_init, now entirely cargo-culted nonsense. v3: - do {} while (!kref_get_unless_zero), makes for a tidier loop (Dave). - pretty kerneldoc - add EXPORT_SYMBOL, helpers&drivers are supposed to use this. v4: Change lockdep annotations to only check whether we release the iter fake lock again (i.e. make sure that iter_put is called), but not check any locking dependecies itself. That seams to require a recursive read lock in trylock mode. Cc: Dave Airlie <airlied@gmail.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Sean Paul <seanpaul@chromium.org> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20161213230814.19598-6-daniel.vetter@ffwll.ch
2016-12-13 23:08:06 +00:00
struct drm_connector_list_iter conn_iter;
/* For atomic drivers only state objects are synchronously updated and
* protected by modeset locks, so check those first. */
drm_connector_list_iter_begin(dev, &conn_iter);
drm: locking&new iterators for connector_list The requirements for connector_list locking are a bit tricky: - We need to be able to jump over zombie conectors (i.e. with refcount == 0, but not yet removed from the list). If instead we require that there's no zombies on the list then the final kref_put must happen under the list protection lock, which means that locking context leaks all over the place. Not pretty - better to deal with zombies and wrap the locking just around the list_del in the destructor. - When we walk the list we must _not_ hold the connector list lock. We walk the connector list at an absolutely massive amounts of places, if all those places can't ever call drm_connector_unreference the code would get unecessarily complicated. - connector_list needs it own lock, again too many places that walk it that we could reuse e.g. mode_config.mutex without resulting in inversions. - Lots of code uses these loops to look-up a connector, i.e. they want to be able to call drm_connector_reference. But on the other hand we want connectors to stay on that list until they're dead (i.e. connector_list can't hold a full reference), which means despite the "can't hold lock for the loop body" rule we need to make sure a connector doesn't suddenly become a zombie. At first Dave&I discussed various horror-show approaches using srcu, but turns out it's fairly easy: - For the loop body we always hold an additional reference to the current connector. That means it can't zombify, and it also means it'll stay on the list, which means we can use it as our iterator to find the next connector. - When we try to find the next connector we only have to jump over zombies. To make sure we don't chase bad pointers that entire loop is protected with the new connect_list_lock spinlock. And because we know that we're starting out with a non-zombie (need to drop our reference for the old connector only after we have our new one), we're guranteed to still be on the connector_list and either find the next non-zombie or complete the iteration. - Only downside is that we need to make sure that the temporary reference for the loop body doesn't leak. iter_get/put() functions + lockdep make sure that's the case. - To avoid a flag day the new iterator macro has an _iter postfix. We can rename it back once all the users of the unsafe version are gone (there's about 100 list walkers for the connector_list). For now this patch only converts all the list walking in the core, leaving helpers and drivers for later patches. The nice thing is that we can now finally remove 2 FIXME comments from the register/unregister functions. v2: - use irqsafe spinlocks, so that we can use this in drm_state_dump too. - nuke drm_modeset_lock_all from drm_connector_init, now entirely cargo-culted nonsense. v3: - do {} while (!kref_get_unless_zero), makes for a tidier loop (Dave). - pretty kerneldoc - add EXPORT_SYMBOL, helpers&drivers are supposed to use this. v4: Change lockdep annotations to only check whether we release the iter fake lock again (i.e. make sure that iter_put is called), but not check any locking dependecies itself. That seams to require a recursive read lock in trylock mode. Cc: Dave Airlie <airlied@gmail.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Sean Paul <seanpaul@chromium.org> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20161213230814.19598-6-daniel.vetter@ffwll.ch
2016-12-13 23:08:06 +00:00
drm_for_each_connector_iter(connector, &conn_iter) {
if (!connector->state)
continue;
uses_atomic = true;
if (connector->state->best_encoder != encoder)
continue;
drm_connector_list_iter_end(&conn_iter);
return connector->state->crtc;
}
drm_connector_list_iter_end(&conn_iter);
/* Don't return stale data (e.g. pending async disable). */
if (uses_atomic)
return NULL;
return encoder->crtc;
}
int drm_mode_getencoder(struct drm_device *dev, void *data,
struct drm_file *file_priv)
{
struct drm_mode_get_encoder *enc_resp = data;
struct drm_encoder *encoder;
struct drm_crtc *crtc;
if (!drm_core_check_feature(dev, DRIVER_MODESET))
return -EINVAL;
encoder = drm_encoder_find(dev, enc_resp->encoder_id);
if (!encoder)
return -ENOENT;
drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
crtc = drm_encoder_get_crtc(encoder);
if (crtc)
enc_resp->crtc_id = crtc->base.id;
else
enc_resp->crtc_id = 0;
drm_modeset_unlock(&dev->mode_config.connection_mutex);
enc_resp->encoder_type = encoder->encoder_type;
enc_resp->encoder_id = encoder->base.id;
enc_resp->possible_crtcs = encoder->possible_crtcs;
enc_resp->possible_clones = encoder->possible_clones;
return 0;
}