On Wed, Mar 29, 2017 at 12:16:50PM +0200, Maarten Lankhorst wrote:
> mode_valid() and get_modes() called
> from drm_helper_probe_single_connector_modes()
> may need to look at connector->state because what a valid mode is may
> depend on connector properties being set. For example some HDMI modes
> might be rejected when a connector property forces the connector
> into DVI mode.
>
> Some implementations of detect() already lock all state,
> so we have to pass an acquire_ctx to them to prevent a deadlock.
>
> This means changing the function signature of detect() slightly,
> and passing the acquire_ctx for locking multiple crtc's.
> It might be NULL, in which case expensive operations should be avoided.
>
> intel_dp.c however ignores the force flag, so still lock
> connection_mutex there if needed.
>
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Cc: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>
> Cc: Manasi Navare <manasi.d.navare@xxxxxxxxx>
Hm only noticed this now, but mixing up force with the acquire_ctx sounds
like very bad interface design. Yes, the only user of the new hook works
like that, but that's really accidental I think. I think just having the
ctx everywhere (for atomic drivers at least) would be a lot safer. This is
extremely surprising (and undocumented suprise at that).
> ---
> drivers/gpu/drm/drm_probe_helper.c | 41 ++++++++++++++++++++++++++++++------
> drivers/gpu/drm/i915/intel_crt.c | 29 +++++++++++++------------
> drivers/gpu/drm/i915/intel_display.c | 25 +++++++++++-----------
> drivers/gpu/drm/i915/intel_dp.c | 22 ++++++++++++-------
> drivers/gpu/drm/i915/intel_drv.h | 8 +++----
> drivers/gpu/drm/i915/intel_hotplug.c | 6 +++++-
> drivers/gpu/drm/i915/intel_tv.c | 24 ++++++++++-----------
> include/drm/drm_connector.h | 5 +++++
> 8 files changed, 101 insertions(+), 59 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
> index 85005d57bde6..a48cff963871 100644
> --- a/drivers/gpu/drm/drm_probe_helper.c
> +++ b/drivers/gpu/drm/drm_probe_helper.c
> @@ -169,11 +169,15 @@ void drm_kms_helper_poll_enable(struct drm_device *dev)
> EXPORT_SYMBOL(drm_kms_helper_poll_enable);
>
> static enum drm_connector_status
> -drm_connector_detect(struct drm_connector *connector, bool force)
> +drm_connector_detect(struct drm_connector *connector,
> + struct drm_modeset_acquire_ctx *ctx)
> {
> - return connector->funcs->detect ?
> - connector->funcs->detect(connector, force) :
> - connector_status_connected;
> + if (connector->funcs->detect_ctx)
> + return connector->funcs->detect_ctx(connector, ctx);
> + else if (connector->funcs->detect)
> + return connector->funcs->detect(connector, !!ctx);
> + else
> + return connector_status_connected;
> }
>
> /**
> @@ -239,15 +243,27 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
> struct drm_display_mode *mode;
> const struct drm_connector_helper_funcs *connector_funcs =
> connector->helper_private;
> - int count = 0;
> + int count = 0, ret;
> int mode_flags = 0;
> bool verbose_prune = true;
> enum drm_connector_status old_status;
> + struct drm_modeset_acquire_ctx ctx;
>
> WARN_ON(!mutex_is_locked(&dev->mode_config.mutex));
>
> + drm_modeset_acquire_init(&ctx, 0);
> +
> DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n", connector->base.id,
> connector->name);
> +
> +retry:
> + ret = drm_modeset_lock(&dev->mode_config.connection_mutex, &ctx);
> + if (ret == -EDEADLK) {
> + drm_modeset_backoff(&ctx);
> + goto retry;
> + } else
> + WARN_ON(ret < 0);
> +
> /* set all old modes to the stale state */
> list_for_each_entry(mode, &connector->modes, head)
> mode->status = MODE_STALE;
> @@ -263,7 +279,15 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
> if (connector->funcs->force)
> connector->funcs->force(connector);
> } else {
> - connector->status = drm_connector_detect(connector, true);
> + ret = drm_connector_detect(connector, &ctx);
> +
> + if (ret == -EDEADLK) {
> + drm_modeset_backoff(&ctx);
> + goto retry;
> + } else if (WARN(ret < 0, "Invalid return value %i for connector detection\n", ret))
> + ret = connector_status_unknown;
> +
> + connector->status = ret;
> }
>
> /*
> @@ -355,6 +379,9 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
> prune:
> drm_mode_prune_invalid(dev, &connector->modes, verbose_prune);
>
> + drm_modeset_drop_locks(&ctx);
> + drm_modeset_acquire_fini(&ctx);
> +
> if (list_empty(&connector->modes))
> return 0;
>
> @@ -440,7 +467,7 @@ static void output_poll_execute(struct work_struct *work)
>
> repoll = true;
>
> - connector->status = drm_connector_detect(connector, false);
> + connector->status = drm_connector_detect(connector, NULL);
> if (old_status != connector->status) {
> const char *old, *new;
>
> diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
> index 8c82607294c6..1186c3f5fea0 100644
> --- a/drivers/gpu/drm/i915/intel_crt.c
> +++ b/drivers/gpu/drm/i915/intel_crt.c
> @@ -669,19 +669,19 @@ static const struct dmi_system_id intel_spurious_crt_detect[] = {
> { }
> };
>
> -static enum drm_connector_status
> -intel_crt_detect(struct drm_connector *connector, bool force)
> +static int
> +intel_crt_detect(struct drm_connector *connector,
> + struct drm_modeset_acquire_ctx *ctx)
> {
> struct drm_i915_private *dev_priv = to_i915(connector->dev);
> struct intel_crt *crt = intel_attached_crt(connector);
> struct intel_encoder *intel_encoder = &crt->base;
> - enum drm_connector_status status;
> + int status, ret;
> struct intel_load_detect_pipe tmp;
> - struct drm_modeset_acquire_ctx ctx;
>
> DRM_DEBUG_KMS("[CONNECTOR:%d:%s] force=%d\n",
> connector->base.id, connector->name,
> - force);
> + !!ctx);
>
> /* Skip machines without VGA that falsely report hotplug events */
> if (dmi_check_system(intel_spurious_crt_detect))
> @@ -716,15 +716,19 @@ intel_crt_detect(struct drm_connector *connector, bool force)
> goto out;
> }
>
> - if (!force) {
> + if (!ctx) {
> status = connector->status;
> goto out;
> }
>
> - drm_modeset_acquire_init(&ctx, 0);
> -
> /* for pre-945g platforms use load detect */
> - if (intel_get_load_detect_pipe(connector, NULL, &tmp, &ctx)) {
> + ret = intel_get_load_detect_pipe(connector, NULL, &tmp, ctx);
> + if (ret < 0) {
> + status = ret;
> + goto out;
> + }
> +
> + if (ret > 0) {
> if (intel_crt_detect_ddc(connector))
> status = connector_status_connected;
> else if (INTEL_GEN(dev_priv) < 4)
> @@ -734,13 +738,10 @@ intel_crt_detect(struct drm_connector *connector, bool force)
> status = connector_status_disconnected;
> else
> status = connector_status_unknown;
> - intel_release_load_detect_pipe(connector, &tmp, &ctx);
> + intel_release_load_detect_pipe(connector, &tmp, ctx);
> } else
> status = connector_status_unknown;
>
> - drm_modeset_drop_locks(&ctx);
> - drm_modeset_acquire_fini(&ctx);
> -
> out:
> intel_display_power_put(dev_priv, intel_encoder->power_domain);
> return status;
> @@ -811,7 +812,7 @@ void intel_crt_reset(struct drm_encoder *encoder)
>
> static const struct drm_connector_funcs intel_crt_connector_funcs = {
> .dpms = drm_atomic_helper_connector_dpms,
> - .detect = intel_crt_detect,
> + .detect_ctx = intel_crt_detect,
> .fill_modes = drm_helper_probe_single_connector_modes,
> .late_register = intel_connector_register,
> .early_unregister = intel_connector_unregister,
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index a79063fac951..baa8d836c8e7 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -9503,10 +9503,10 @@ static int intel_modeset_setup_plane_state(struct drm_atomic_state *state,
> return 0;
> }
>
> -bool intel_get_load_detect_pipe(struct drm_connector *connector,
> - struct drm_display_mode *mode,
> - struct intel_load_detect_pipe *old,
> - struct drm_modeset_acquire_ctx *ctx)
> +int intel_get_load_detect_pipe(struct drm_connector *connector,
> + struct drm_display_mode *mode,
> + struct intel_load_detect_pipe *old,
> + struct drm_modeset_acquire_ctx *ctx)
> {
> struct intel_crtc *intel_crtc;
> struct intel_encoder *intel_encoder =
> @@ -9529,10 +9529,7 @@ bool intel_get_load_detect_pipe(struct drm_connector *connector,
>
> old->restore_state = NULL;
>
> -retry:
> - ret = drm_modeset_lock(&config->connection_mutex, ctx);
> - if (ret)
> - goto fail;
> + WARN_ON(!drm_modeset_is_locked(&config->connection_mutex));
>
> /*
> * Algorithm gets a little messy:
> @@ -9682,10 +9679,8 @@ bool intel_get_load_detect_pipe(struct drm_connector *connector,
> restore_state = NULL;
> }
>
> - if (ret == -EDEADLK) {
> - drm_modeset_backoff(ctx);
> - goto retry;
> - }
> + if (ret == -EDEADLK)
> + return ret;
>
> return false;
> }
> @@ -15112,6 +15107,7 @@ static void intel_enable_pipe_a(struct drm_device *dev)
> struct drm_connector *crt = NULL;
> struct intel_load_detect_pipe load_detect_temp;
> struct drm_modeset_acquire_ctx *ctx = dev->mode_config.acquire_ctx;
> + int ret;
>
> /* We can't just switch on the pipe A, we need to set things up with a
> * proper mode and output configuration. As a gross hack, enable pipe A
> @@ -15128,7 +15124,10 @@ static void intel_enable_pipe_a(struct drm_device *dev)
> if (!crt)
> return;
>
> - if (intel_get_load_detect_pipe(crt, NULL, &load_detect_temp, ctx))
> + ret = intel_get_load_detect_pipe(crt, NULL, &load_detect_temp, ctx);
> + WARN(ret < 0, "All modeset mutexes are locked, but intel_get_load_detect_pipe failed\n");
> +
> + if (ret > 0)
> intel_release_load_detect_pipe(crt, &load_detect_temp, ctx);
> }
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index fd96a6cf7326..10b3727b7381 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -4567,7 +4567,8 @@ intel_dp_unset_edid(struct intel_dp *intel_dp)
> }
>
> static enum drm_connector_status
> -intel_dp_long_pulse(struct intel_connector *intel_connector)
> +intel_dp_long_pulse(struct intel_connector *intel_connector,
> + struct drm_modeset_acquire_ctx *ctx)
> {
> struct drm_connector *connector = &intel_connector->base;
> struct intel_dp *intel_dp = intel_attached_dp(connector);
> @@ -4640,9 +4641,13 @@ intel_dp_long_pulse(struct intel_connector *intel_connector)
> * check links status, there has been known issues of
> * link loss triggerring long pulse!!!!
> */
> - drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
> + if (!ctx)
> + drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
> +
> intel_dp_check_link_status(intel_dp);
> - drm_modeset_unlock(&dev->mode_config.connection_mutex);
> +
> + if (!ctx)
> + drm_modeset_unlock(&dev->mode_config.connection_mutex);
> goto out;
> }
>
> @@ -4682,18 +4687,19 @@ intel_dp_long_pulse(struct intel_connector *intel_connector)
> return status;
> }
>
> -static enum drm_connector_status
> -intel_dp_detect(struct drm_connector *connector, bool force)
> +static int
> +intel_dp_detect(struct drm_connector *connector,
> + struct drm_modeset_acquire_ctx *ctx)
> {
> struct intel_dp *intel_dp = intel_attached_dp(connector);
> - enum drm_connector_status status = connector->status;
> + int status = connector->status;
>
> DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n",
> connector->base.id, connector->name);
>
> /* If full detect is not performed yet, do a full detect */
> if (!intel_dp->detect_done)
> - status = intel_dp_long_pulse(intel_dp->attached_connector);
> + status = intel_dp_long_pulse(intel_dp->attached_connector, ctx);
>
> intel_dp->detect_done = false;
>
> @@ -5014,7 +5020,7 @@ void intel_dp_encoder_reset(struct drm_encoder *encoder)
>
> static const struct drm_connector_funcs intel_dp_connector_funcs = {
> .dpms = drm_atomic_helper_connector_dpms,
> - .detect = intel_dp_detect,
> + .detect_ctx = intel_dp_detect,
> .force = intel_dp_force,
> .fill_modes = drm_helper_probe_single_connector_modes,
> .set_property = intel_dp_set_property,
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index e24641b559e2..6ea8b9cd68c5 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1362,10 +1362,10 @@ int ironlake_get_lanes_required(int target_clock, int link_bw, int bpp);
> void vlv_wait_port_ready(struct drm_i915_private *dev_priv,
> struct intel_digital_port *dport,
> unsigned int expected_mask);
> -bool intel_get_load_detect_pipe(struct drm_connector *connector,
> - struct drm_display_mode *mode,
> - struct intel_load_detect_pipe *old,
> - struct drm_modeset_acquire_ctx *ctx);
> +int intel_get_load_detect_pipe(struct drm_connector *connector,
> + struct drm_display_mode *mode,
> + struct intel_load_detect_pipe *old,
> + struct drm_modeset_acquire_ctx *ctx);
> void intel_release_load_detect_pipe(struct drm_connector *connector,
> struct intel_load_detect_pipe *old,
> struct drm_modeset_acquire_ctx *ctx);
> diff --git a/drivers/gpu/drm/i915/intel_hotplug.c b/drivers/gpu/drm/i915/intel_hotplug.c
> index 7d210097eefa..d2d2af7ef305 100644
> --- a/drivers/gpu/drm/i915/intel_hotplug.c
> +++ b/drivers/gpu/drm/i915/intel_hotplug.c
> @@ -243,7 +243,11 @@ static bool intel_hpd_irq_event(struct drm_device *dev,
> WARN_ON(!mutex_is_locked(&dev->mode_config.mutex));
> old_status = connector->status;
>
> - connector->status = connector->funcs->detect(connector, false);
> + if (connector->funcs->detect_ctx)
> + connector->status = connector->funcs->detect_ctx(connector, NULL);
> + else
> + connector->status = connector->funcs->detect(connector, false);
> +
> if (old_status == connector->status)
> return false;
>
> diff --git a/drivers/gpu/drm/i915/intel_tv.c b/drivers/gpu/drm/i915/intel_tv.c
> index 6ed1a3ce47b7..d2c0120048b2 100644
> --- a/drivers/gpu/drm/i915/intel_tv.c
> +++ b/drivers/gpu/drm/i915/intel_tv.c
> @@ -1315,8 +1315,9 @@ static void intel_tv_find_better_format(struct drm_connector *connector)
> * Currently this always returns CONNECTOR_STATUS_UNKNOWN, as we need to be sure
> * we have a pipe programmed in order to probe the TV.
> */
> -static enum drm_connector_status
> -intel_tv_detect(struct drm_connector *connector, bool force)
> +static int
> +intel_tv_detect(struct drm_connector *connector,
> + struct drm_modeset_acquire_ctx *ctx)
> {
> struct drm_display_mode mode;
> struct intel_tv *intel_tv = intel_attached_tv(connector);
> @@ -1325,27 +1326,26 @@ intel_tv_detect(struct drm_connector *connector, bool force)
>
> DRM_DEBUG_KMS("[CONNECTOR:%d:%s] force=%d\n",
> connector->base.id, connector->name,
> - force);
> + !!ctx);
>
> mode = reported_modes[0];
>
> - if (force) {
> + if (ctx) {
> struct intel_load_detect_pipe tmp;
> - struct drm_modeset_acquire_ctx ctx;
> + int ret;
>
> - drm_modeset_acquire_init(&ctx, 0);
> + ret = intel_get_load_detect_pipe(connector, &mode, &tmp, ctx);
> + if (ret < 0)
> + return ret;
>
> - if (intel_get_load_detect_pipe(connector, &mode, &tmp, &ctx)) {
> + if (ret > 0) {
> type = intel_tv_detect_type(intel_tv, connector);
> - intel_release_load_detect_pipe(connector, &tmp, &ctx);
> + intel_release_load_detect_pipe(connector, &tmp, ctx);
> status = type < 0 ?
> connector_status_disconnected :
> connector_status_connected;
> } else
> status = connector_status_unknown;
> -
> - drm_modeset_drop_locks(&ctx);
> - drm_modeset_acquire_fini(&ctx);
> } else
> return connector->status;
>
> @@ -1516,7 +1516,7 @@ intel_tv_set_property(struct drm_connector *connector, struct drm_property *prop
>
> static const struct drm_connector_funcs intel_tv_connector_funcs = {
> .dpms = drm_atomic_helper_connector_dpms,
> - .detect = intel_tv_detect,
> + .detect_ctx = intel_tv_detect,
> .late_register = intel_connector_register,
> .early_unregister = intel_connector_unregister,
> .destroy = intel_tv_destroy,
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> index 941f57f311aa..834d1ba709ea 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -32,6 +32,7 @@
> struct drm_device;
>
> struct drm_connector_helper_funcs;
> +struct drm_modeset_acquire_ctx;
> struct drm_device;
> struct drm_crtc;
> struct drm_encoder;
> @@ -385,6 +386,10 @@ struct drm_connector_funcs {
> enum drm_connector_status (*detect)(struct drm_connector *connector,
> bool force);
>
> + /* ctx = NULL <> detect(force = false), but may also return -EDEADLK. */
At least copy-paste the kernel-doc for the existing hook. And run make
hmtldocs to check it ...
When doing that you'll also notice that there's a FIXME telling you the
hook should probably be in drm_connector_helper_funcs.
Thanks, Daniel
> + int (*detect_ctx)(struct drm_connector *connector,
> + struct drm_modeset_acquire_ctx *ctx);
> +
> /**
> * @force:
> *
> --
> 2.7.4
>
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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