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b=KuUvxrCsOWLFOWrpuYLTa6ONwajPti3MPpaqogjxRB28dmnc/lEu2WFkSg6pzty52 e5uyjWS5qTNVoHlFudoM9Fmz4vgVh4P9ue1K5FqHuGtJNRqUYjLjvpsQy7lc8fX9KN u0EDNXsfRZGr6PxrpvBGQ9m/N/qFow+c9cSo3IsE= Date: Tue, 5 Nov 2024 11:47:08 +0200 From: Laurent Pinchart To: Herve Codina Cc: Maxime Ripard , Andrzej Hajda , Neil Armstrong , Robert Foss , Jonas Karlman , Jernej Skrabec , David Airlie , Simona Vetter , Maarten Lankhorst , Thomas Zimmermann , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Marek Vasut , dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Luca Ceresoli , Thomas Petazzoni Subject: Re: [PATCH 2/2] drm: bridge: ti-sn65dsi83: Add error recovery mechanism Message-ID: <20241105094708.GK27775@pendragon.ideasonboard.com> References: <20241024095539.1637280-1-herve.codina@bootlin.com> <20241024095539.1637280-3-herve.codina@bootlin.com> <20241027162350.GA15853@pendragon.ideasonboard.com> <20241028091331.6f67e29e@bootlin.com> <20241028112857.GF24052@pendragon.ideasonboard.com> <20241028-nebulous-yellow-dragon-2cfb5f@houat> <20241028132858.GE6081@pendragon.ideasonboard.com> <20241028-great-charming-flounder-23fc9b@houat> <20241028140913.GG6081@pendragon.ideasonboard.com> <20241105091503.48f69586@bootlin.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20241105091503.48f69586@bootlin.com> On Tue, Nov 05, 2024 at 09:15:03AM +0100, Herve Codina wrote: > On Mon, 28 Oct 2024 16:09:13 +0200 Laurent Pinchart wrote: > > On Mon, Oct 28, 2024 at 02:55:47PM +0100, Maxime Ripard wrote: > > > On Mon, Oct 28, 2024 at 03:28:58PM +0200, Laurent Pinchart wrote: > > > > On Mon, Oct 28, 2024 at 01:21:45PM +0100, Maxime Ripard wrote: > > > > > On Mon, Oct 28, 2024 at 01:28:57PM +0200, Laurent Pinchart wrote: > > > > > > On Mon, Oct 28, 2024 at 09:13:31AM +0100, Herve Codina wrote: > > > > > > > On Sun, 27 Oct 2024 18:23:50 +0200 Laurent Pinchart wrote: > > > > > > > > > > > > > > [...] > > > > > > > > > +static int sn65dsi83_reset_pipeline(struct sn65dsi83 *sn65dsi83) > > > > > > > > > +{ > > > > > > > > > + struct drm_device *dev = sn65dsi83->bridge.dev; > > > > > > > > > + struct drm_modeset_acquire_ctx ctx; > > > > > > > > > + struct drm_atomic_state *state; > > > > > > > > > + int err; > > > > > > > > > + > > > > > > > > > + /* Use operation done in drm_atomic_helper_suspend() followed by > > > > > > > > > + * operation done in drm_atomic_helper_resume() but without releasing > > > > > > > > > + * the lock between suspend()/resume() > > > > > > > > > + */ > > > > > > > > > + > > > > > > > > > + DRM_MODESET_LOCK_ALL_BEGIN(dev, ctx, 0, err); > > > > > > > > > + > > > > > > > > > + state = drm_atomic_helper_duplicate_state(dev, &ctx); > > > > > > > > > + if (IS_ERR(state)) { > > > > > > > > > + err = PTR_ERR(state); > > > > > > > > > + goto unlock; > > > > > > > > > + } > > > > > > > > > + > > > > > > > > > + err = drm_atomic_helper_disable_all(dev, &ctx); > > > > > > > > > + if (err < 0) > > > > > > > > > + goto unlock; > > > > > > > > > + > > > > > > > > > + drm_mode_config_reset(dev); > > > > > > > > > + > > > > > > > > > + err = drm_atomic_helper_commit_duplicated_state(state, &ctx); > > > > > > > > > > > > > > > > Committing a full atomic state from a bridge driver in an asynchronous > > > > > > > > way seems quite uncharted territory, and it worries me. It's also a very > > > > > > > > heavyweight, you disable all outputs here, instead of focussing on the > > > > > > > > output connected to the bridge. Can you either implement something more > > > > > > > > local, resetting the bridge only, or create a core helper to handle this > > > > > > > > kind of situation, on a per-output basis ? > > > > > > > > > > > > > > A full restart of the bridge (power off/on) is needed and so we need to > > > > > > > redo the initialization sequence. This initialization sequence has to be > > > > > > > done with the DSI data lanes (bridge inputs) driven in LP11 state and so > > > > > > > without any video stream. Only focussing on bridge outputs will not be > > > > > > > sufficient. That's why I brought the pipeline down and restarted it. > > > > > > > > > > > > Fair point. > > > > > > > > > > > > > Of course, I can copy/paste sn65dsi83_reset_pipeline() to a core helper > > > > > > > function. Is drm_atomic_helper_reset_all() could be a good candidate? > > > > > > > > > > > > The helper should operate on a single output, unrelated outputs should > > > > > > not be affected. > > > > > > > > > > Also, you don't want to reset anything, you just want the last commit to > > > > > be replayed. > > > > > > > > I'm not sure about that. If the last commit is just a page flip, that > > > > won't help, will it ? > > > > > > The alternative would be that you start anew with a blank state, which > > > effectively drops every configuration that has been done by userspace. > > > This is terrible. > > > > > > And a page flip wouldn't have affected the connector and > > > connector->state would still be to the last state that affected it, so > > > it would work. > > > > Ah right, you didn't mean replaying the last commit then, but first > > disabling the output and then restoring the current state ? That should > > work. > > Thanks for the feedback. > > If I understand correctly, I should try to disable the output. > What is the 'output' exactly, the connector? Yes, the output maps to the connector. > How can I disable it? Can you give me some pointers? By creating a commit that disables it :-) Conceptually that's about setting the same properties you would from userspace. Maybe look at drm_atomic_helper_disable_all() to see if you can make a version that operates on a single output. > Further more, is disabling the "output" disable the whole path where the > bridge is located? It should yes. > I mean, I need to power off/on the bridge and re-init it with its input DSI > lines in LP11. -- Regards, Laurent Pinchart