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[108.49.102.102]) by smtp.gmail.com with ESMTPSA id o20sm637191qtk.56.2020.07.08.11.46.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Jul 2020 11:46:56 -0700 (PDT) Message-ID: <1b6c5646a4bd7810386163e4b6f1c5f3f1ac122b.camel@redhat.com> Subject: Re: [PATCH 1/2] drm/probe_helper: Add drm_connector_helper_funcs.mode_valid_ctx From: Lyude Paul To: imre.deak@intel.com Date: Wed, 08 Jul 2020 14:46:55 -0400 In-Reply-To: <20200708184521.GC21536@ideak-desk.fi.intel.com> References: <20200526182313.4005-1-lyude@redhat.com> <20200526182313.4005-2-lyude@redhat.com> <20200707224036.GA22747@ideak-desk.fi.intel.com> <20200708184521.GC21536@ideak-desk.fi.intel.com> Organization: Red Hat User-Agent: Evolution 3.36.3 (3.36.3-1.fc32) MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=lyude@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: lyude@redhat.com Cc: David Airlie , Thomas Zimmermann , Lee Shawn C , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Wed, 2020-07-08 at 21:45 +0300, Imre Deak wrote: > On Wed, Jul 08, 2020 at 01:25:14PM -0400, Lyude Paul wrote: > > JFYI - found an issue with this patch that wouldn't have shown up on i915, > > info > > down below: > > > > On Wed, 2020-07-08 at 01:40 +0300, Imre Deak wrote: > > > Sorry for the delay, the review as I promised: > > > > > > On Tue, May 26, 2020 at 02:23:09PM -0400, Lyude Paul wrote: > > > > This is just an atomic version of mode_valid, which is intended to be > > > > used for situations where a driver might need to check the atomic state > > > > of objects other than the connector itself. One such example is with > > > > MST, where the maximum possible bandwidth on a connector can change > > > > dynamically irregardless of the display configuration. > > > > > > > > Signed-off-by: Lyude Paul > > > > Cc: Lee Shawn C > > > > Tested-by: Lee Shawn C > > > > --- > > > > drivers/gpu/drm/drm_crtc_helper_internal.h | 6 +- > > > > drivers/gpu/drm/drm_probe_helper.c | 65 ++++++++++++++-------- > > > > include/drm/drm_modeset_helper_vtables.h | 41 ++++++++++++++ > > > > 3 files changed, 88 insertions(+), 24 deletions(-) > > > > > > > > diff --git a/drivers/gpu/drm/drm_crtc_helper_internal.h > > > > b/drivers/gpu/drm/drm_crtc_helper_internal.h > > > > index f0a66ef47e5ad..ca767cba6094d 100644 > > > > --- a/drivers/gpu/drm/drm_crtc_helper_internal.h > > > > +++ b/drivers/gpu/drm/drm_crtc_helper_internal.h > > > > @@ -73,8 +73,10 @@ enum drm_mode_status drm_crtc_mode_valid(struct > > > > drm_crtc > > > > *crtc, > > > > const struct drm_display_mode > > > > *mode); > > > > enum drm_mode_status drm_encoder_mode_valid(struct drm_encoder > > > > *encoder, > > > > const struct > > > > drm_display_mode > > > > *mode); > > > > -enum drm_mode_status drm_connector_mode_valid(struct drm_connector > > > > *connector, > > > > - struct drm_display_mode > > > > *mode); > > > > +enum drm_mode_status > > > > +drm_connector_mode_valid(struct drm_connector *connector, > > > > + struct drm_display_mode *mode, > > > > + struct drm_modeset_acquire_ctx *ctx); > > > > > > > > struct drm_encoder * > > > > drm_connector_get_single_encoder(struct drm_connector *connector); > > > > diff --git a/drivers/gpu/drm/drm_probe_helper.c > > > > b/drivers/gpu/drm/drm_probe_helper.c > > > > index 466dfbba82564..3132784736841 100644 > > > > --- a/drivers/gpu/drm/drm_probe_helper.c > > > > +++ b/drivers/gpu/drm/drm_probe_helper.c > > > > @@ -86,16 +86,17 @@ drm_mode_validate_flag(const struct drm_display_mode > > > > *mode, > > > > return MODE_OK; > > > > } > > > > > > > > -static enum drm_mode_status > > > > +static int > > > > drm_mode_validate_pipeline(struct drm_display_mode *mode, > > > > - struct drm_connector *connector) > > > > + struct drm_connector *connector, > > > > + struct drm_modeset_acquire_ctx *ctx) > > > > { > > > > struct drm_device *dev = connector->dev; > > > > - enum drm_mode_status ret = MODE_OK; > > > > struct drm_encoder *encoder; > > > > + int ret = MODE_OK; > > > > > > > > /* Step 1: Validate against connector */ > > > > - ret = drm_connector_mode_valid(connector, mode); > > > > + ret = drm_connector_mode_valid(connector, mode, ctx); > > > > if (ret != MODE_OK) > > > > return ret; > > > > > > > > @@ -196,16 +197,23 @@ enum drm_mode_status drm_encoder_mode_valid(struct > > > > drm_encoder *encoder, > > > > return encoder_funcs->mode_valid(encoder, mode); > > > > } > > > > > > > > -enum drm_mode_status drm_connector_mode_valid(struct drm_connector > > > > *connector, > > > > - struct drm_display_mode > > > > *mode) > > > > +int > > > > +drm_connector_mode_valid(struct drm_connector *connector, > > > > + struct drm_display_mode *mode, > > > > + struct drm_modeset_acquire_ctx *ctx) > > > > { > > > > const struct drm_connector_helper_funcs *connector_funcs = > > > > connector->helper_private; > > > > > > > > - if (!connector_funcs || !connector_funcs->mode_valid) > > > > + if (!connector_funcs) > > > > return MODE_OK; > > > > > > > > - return connector_funcs->mode_valid(connector, mode); > > > > + if (connector_funcs->mode_valid_ctx) > > > > + return connector_funcs->mode_valid_ctx(connector, mode, > > > > ctx); > > > > + else if (connector_funcs->mode_valid) > > > > + return connector_funcs->mode_valid(connector, mode); > > > > + else > > > > + return MODE_OK; > > > > } > > > > > > > > #define DRM_OUTPUT_POLL_PERIOD (10*HZ) > > > > @@ -375,8 +383,9 @@ EXPORT_SYMBOL(drm_helper_probe_detect); > > > > * (if specified) > > > > * - drm_mode_validate_flag() checks the modes against basic > > > > connector > > > > * capabilities > > > > (interlace_allowed,doublescan_allowed,stereo_allowed) > > > > - * - the optional &drm_connector_helper_funcs.mode_valid helper can > > > > perform > > > > - * driver and/or sink specific checks > > > > + * - the optional &drm_connector_helper_funcs.mode_valid or > > > > + * &drm_connector_helper_funcs.mode_valid_ctx helpers can perform > > > > driver > > > > + * and/or sink specific checks > > > > * - the optional &drm_crtc_helper_funcs.mode_valid, > > > > * &drm_bridge_funcs.mode_valid and > > > > &drm_encoder_helper_funcs.mode_valid > > > > * helpers can perform driver and/or source specific checks which > > > > are > > > > also > > > > @@ -507,22 +516,34 @@ int drm_helper_probe_single_connector_modes(struct > > > > drm_connector *connector, > > > > mode_flags |= DRM_MODE_FLAG_3D_MASK; > > > > > > > > list_for_each_entry(mode, &connector->modes, head) { > > > > - if (mode->status == MODE_OK) > > > > - mode->status = drm_mode_validate_driver(dev, > > > > mode); > > > > + if (mode->status != MODE_OK) > > > > + continue; > > > > + > > > > + mode->status = drm_mode_validate_driver(dev, mode); > > > > + if (mode->status != MODE_OK) > > > > + continue; > > > > > > > > - if (mode->status == MODE_OK) > > > > - mode->status = drm_mode_validate_size(mode, > > > > maxX, maxY); > > > > + mode->status = drm_mode_validate_size(mode, maxX, maxY); > > > > + if (mode->status != MODE_OK) > > > > + continue; > > > > > > > > - if (mode->status == MODE_OK) > > > > - mode->status = drm_mode_validate_flag(mode, > > > > mode_flags); > > > > + mode->status = drm_mode_validate_flag(mode, mode_flags); > > > > + if (mode->status != MODE_OK) > > > > + continue; > > > > > > > > - if (mode->status == MODE_OK) > > > > - mode->status = drm_mode_validate_pipeline(mode, > > > > - connec > > > > tor); > > > > + ret = drm_mode_validate_pipeline(mode, connector, &ctx); > > > > + if (ret == -EDEADLK) { > > > > + drm_modeset_backoff(&ctx); > > > > + goto retry; > > > > + } else if (WARN_ON_ONCE(ret < 0)) { > > > > + mode->status = MODE_BAD; > > > > This check is wrong actually. We define negative values for drm_mode_status > > (MODE_BAD, MODE_ERROR, MODE_STALE) which, at least with how drivers > > currently > > seem to use them, are something we want to treat as not-unexpected errors > > and > > not WARN_ON. > > Ah, yes, missed that. > > > This is a bit annoying because it does mean there's some overlap between > > drm_mode_status and some legitimate errno values (EPERM, ENOENT, ESRCH). > > Luckily > > I can't see any reason why drivers would want to return those, but I think > > we > > should probably print a debugging message when we get any errno values just > > so > > developers don't get confused (also going to add a IS_ERR() equivalent for > > drm_mode_status, but with a different name) > > Maybe I'm missing something, but having negative values in > drm_mode_status doesn't make sense to me, as all the non-zero values > there just mean the mode is incorrect for some reason and should be > pruned. > > Would it make sense to better separate the mode-status value and any > error return value from mode_valid_ctx(), by adding a drm_mode_status * > parameter to the hook and drm_mode_validate_pipeline()? yeah-that would probably make more sense. I will go ahead and do that > > > > > + } else { > > > > + mode->status = ret; > > > > + } > > > > > > > > - if (mode->status == MODE_OK) > > > > - mode->status = drm_mode_validate_ycbcr420(mode, > > > > - connec > > > > tor); > > > > + if (mode->status != MODE_OK) > > > > + continue; > > > > + mode->status = drm_mode_validate_ycbcr420(mode, > > > > connector); > > > > } > > > > > > > > prune: > > > > diff --git a/include/drm/drm_modeset_helper_vtables.h > > > > b/include/drm/drm_modeset_helper_vtables.h > > > > index 421a30f084631..8f020c3424b2b 100644 > > > > --- a/include/drm/drm_modeset_helper_vtables.h > > > > +++ b/include/drm/drm_modeset_helper_vtables.h > > > > @@ -968,6 +968,47 @@ struct drm_connector_helper_funcs { > > > > */ > > > > enum drm_mode_status (*mode_valid)(struct drm_connector > > > > *connector, > > > > struct drm_display_mode > > > > *mode); > > > > + > > > > + /** > > > > + * @mode_valid_ctx: > > > > + * > > > > + * Callback to validate a mode for a connector, irrespective of > > > > the > > > > + * specific display configuration. > > > > + * > > > > + * This callback is used by the probe helpers to filter the mode > > > > list > > > > + * (which is usually derived from the EDID data block from the > > > > sink). > > > > + * See e.g. drm_helper_probe_single_connector_modes(). > > > > + * > > > > + * This function is optional, and is the atomic version of > > > > + * &drm_connector_funcs.mode_valid. > > > > + * > > > > + * To allow for accessing the atomic state of modesetting > > > > objects, the > > > > + * helper libraries always call this with ctx set to a valid > > > > context, > > > > + * and &drm_mode_config.connection_mutex will always be locked > > > > with > > > > + * the ctx parameter set to @ctx. This allows for taking > > > > additional > > > > + * locks as required. > > > > + * > > > > + * Even though additional locks may be acquired, this callback > > > > is > > > > + * still expected not to take any constraints into account which > > > > would > > > > + * be influenced by the currently set display state - such > > > > constraints > > > > + * should be handled in the driver's atomic check. For example, > > > > if a > > > > + * connector shares display bandwidth with other connectors then > > > > it > > > > + * would be ok to validate a mode uses against the maximum > > > > possible > > > ^mode against? > > > > > > Reviewed-by: Imre Deak > > > > > > > + * bandwidth of the connector. But it wouldn't be ok to take the > > > > + * current bandwidth usage of other connectors into account, as > > > > this > > > > + * would change depending on the display state. > > > > + * > > > > + * Returns: > > > > + * > > > > + * Either &drm_mode_status.MODE_OK, one of the failure reasons > > > > in > > > > + * &enum drm_mode_status, or -EDEADLK if a deadlock would have > > > > + * occurred and we need to backoff. > > > > + * > > > > + */ > > > > + int (*mode_valid_ctx)(struct drm_connector *connector, > > > > + struct drm_display_mode *mode, > > > > + struct drm_modeset_acquire_ctx *ctx); > > > > + > > > > /** > > > > * @best_encoder: > > > > * > > > > -- > > > > 2.26.2 > > > > > > > > _______________________________________________ > > > > dri-devel mailing list > > > > dri-devel@lists.freedesktop.org > > > > https://lists.freedesktop.org/mailman/listinfo/dri-devel _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel