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bh=un1sepzSSrQyyA7E1EuGMdvogzWZ9PqXPPCQRmW27Io=; b=Al0JkPmXCMyWKJwSKMD/zgMi561P28OTCGtw1w/ulS8iOmM1CI/GUhAcysU+67PDUIL+Vd uwo3RZ01D/S8pUF1px+RS6314PIns7DAUyk0suG62RlPxpE6Xf2SNLAOC/jYGiAHxIsgVX jbGTH5pQtzbTzn8eoqT2GDntvXwjEejIuSGRVGlshP5o3eT4yeAzEn1/FCSg3JzLns5WXf qqgXXqls8zI8Zadt1RADniTCbnCU7G5ARScilubNhH//63BovGULrHoKFAqCuax09s3KsX UKO4WijJBM6WKXBOsct0awVkg62RcMVCinNok49h2EsKRDt1e/TmAxU3H5+FGQ== Message-ID: Date: Mon, 7 Apr 2025 11:50:43 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v9 0/5] drm/bridge: add devm_drm_bridge_alloc() with bridge refcount To: Luca Ceresoli , Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Marek Vasut , Stefan Agner , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , Inki Dae , Jagan Teki , Marek Szyprowski Cc: Thomas Petazzoni , Anusha Srivatsa , Paul Kocialkowski , Dmitry Baryshkov , =?UTF-8?Q?Herv=C3=A9_Codina?= , Hui Pu , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org References: <20250326-drm-bridge-refcount-v9-0-5e0661fe1f84@bootlin.com> Content-Language: en-US From: Louis Chauvet Autocrypt: addr=louis.chauvet@bootlin.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-GND-State: clean X-GND-Score: -100 X-GND-Cause: gggruggvucftvghtrhhoucdtuddrgeefvddrtddtgdduleelkeejucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecuifetpfffkfdpucggtfgfnhhsuhgsshgtrhhisggvnecuuegrihhlohhuthemuceftddunecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpefkffggfgfuvfevfhfhjggtgfesthekredttddvjeenucfhrhhomhepnfhouhhishcuvehhrghuvhgvthcuoehlohhuihhsrdgthhgruhhvvghtsegsohhothhlihhnrdgtohhmqeenucggtffrrghtthgvrhhnpeejgeejgedutdekhfffgfegudeutdetgfeuveegteeftddtfeevueffgfevgfevkeenucffohhmrghinhepkhgvrhhnvghlrdhorhhgpdgsohhothhlihhnrdgtohhmnecukfhppeeltddrkeelrdduieefrdduvdejnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehinhgvthepledtrdekledrudeifedruddvjedphhgvlhhopegludelvddrudeikedrtddrvddvkegnpdhmrghilhhfrhhomheplhhouhhishdrtghhrghuvhgvthessghoohhtlhhinhdrtghomhdpnhgspghrtghpthhtohepfedupdhrtghpthhtoheplhhutggrrdgtvghrvghsohhlihessghoohhtlhhinhdrtghomhdprhgtphhtthhopegrnhgurhiivghjrdhhrghjuggrsehinhhtvghlrdgtohhmpdhrtghpthhtohepnhgvihhlrdgrrhhmshhtrhhonhhgsehlihhnrghrohdrohhrghdprhgtphhtthhopehrfhhoshhssehkv ghrnhgvlhdrohhrghdprhgtphhtthhopefnrghurhgvnhhtrdhpihhntghhrghrthesihguvggrshhonhgsohgrrhgurdgtohhmpdhrtghpthhtohepjhhonhgrsheskhifihgsohhordhsvgdprhgtphhtthhopehjvghrnhgvjhdrshhkrhgrsggvtgesghhmrghilhdrtghomhdprhgtphhtthhopehmrggrrhhtvghnrdhlrghnkhhhohhrshhtsehlihhnuhigrdhinhhtvghlrdgtohhm X-GND-Sasl: louis.chauvet@bootlin.com Le 26/03/2025 à 18:47, Luca Ceresoli a écrit : > This series improves the way DRM bridges are allocated and initialized and > makes them reference-counted. The goal of reference counting is to avoid > use-after-free by drivers which got a pointer to a bridge and keep it > stored and used even after the bridge has been deallocated. > > The overall goal is supporting Linux devices with a DRM pipeline whose > final components can be hot-plugged and hot-unplugged, including one or > more bridges. For more details see the big picture [0]. > > DRM bridge drivers will have to be adapted to the new API -- the change is > trivial for most cases. This series converts two of them to serve as an > example. The remaining ones will be done as a follow-up after this first > part is merged. > > After that, refcounting will have to be added on the two sides: all > functions returning a bridge pointer and all code obtaining such a > pointer. A few examples have been sent in v7 (link below), they are OK, but > I removed them since v8 because they must be merged only after converting > all bridges. > > Here's the grand plan: > > A. add new alloc API and refcounting (this series, at least patches 1-3) > B. after (A), convert all bridge drivers to new API > C. after (A), add documentation and kunit tests > D. after (B), add get/put to drm_bridge_add/remove() + attach/detech() > (patches 3-4 in the v7 series) > E. after (B), convert accessors (including patches 5-9 in the v7 series > which convert drm_bridge_chain_get_first_bridge() and its users); > this is a large work and can be done in chunks > F. after (A), debugfs: show refcount, show removed bridges > > Layout of this: > > 1. Add the new API and refcounting: > > drm/bridge: add devm_drm_bridge_alloc() > drm/bridge: add support for refcounting > drm/bridge: deprecate old-style bridge allocation > > 2. convert a few bridge drivers (bridge providers) to the new API: > > drm/bridge: ti-sn65dsi83: use dynamic lifetime management > drm/bridge: samsung-dsim: use dynamic lifetime management > > [0] https://lore.kernel.org/dri-devel/20250206-hotplug-drm-bridge-v6-0-9d6f2c9c3058@bootlin.com/ > > Signed-off-by: Luca Ceresoli Applied on drm-misc-next, thanks! -- Louis Chauvet, Bootlin Embedded Linux and Kernel engineering https://bootlin.com