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Wed, 2 Feb 2022 03:59:37 -0500 (EST) Date: Wed, 2 Feb 2022 09:59:36 +0100 From: Maxime Ripard To: Jagan Teki Cc: Chen-Yu Tsai , Laurent Pinchart , Neil Armstrong , Robert Foss , Sam Ravnborg , dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-sunxi@googlegroups.com, linux-amarula@amarulasolutions.com Subject: Re: [PATCH v6 1/6] drm: sun4i: dsi: Drop DRM bind race with bridge attach Message-ID: <20220202085936.ogxhpl7u42lubhdd@houat> References: <20211210111711.2072660-1-jagan@amarulasolutions.com> <20211210111711.2072660-2-jagan@amarulasolutions.com> <20211213170223.fx5656vjk3fwizbg@houat> MIME-Version: 1.0 In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220202_005944_900901_4579E7D1 X-CRM114-Status: GOOD ( 20.68 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: multipart/mixed; boundary="===============0742434945360607808==" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org --===============0742434945360607808== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="dwa3ea6vcaiywqfz" Content-Disposition: inline --dwa3ea6vcaiywqfz Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Jan 17, 2022 at 09:12:37PM +0530, Jagan Teki wrote: > On Mon, Dec 13, 2021 at 10:32 PM Maxime Ripard wrote: > > > > On Fri, Dec 10, 2021 at 04:47:06PM +0530, Jagan Teki wrote: > > > Existing host driver will keep looking for DRM pointer in > > > sun6i_dsi_attach and defers even if the particular DSI device > > > is found for the first time. Meanwhile it triggers the bind > > > callback and gets the DRM pointer and then continues the > > > sun6i_dsi_attach. > > > > > > This makes a deadlock situation if sun6i_dsi_attach is trying > > > to find the bridge. > > > > I'm not sure what you mean by deadlock here, there's no lock involved? >=20 > deadlock parse here for general understanding, where bind is trying to > attach bridge but drm pointer is not available that point and drm > pointer will available only when bind done. This is what I'm calling > as deadlock here. Have you read: https://www.kernel.org/doc/html/latest/gpu/drm-kms-helpers.html#special-car= e-with-mipi-dsi-bridges Maxime --dwa3ea6vcaiywqfz Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQRcEzekXsqa64kGDp7j7w1vZxhRxQUCYfpH+AAKCRDj7w1vZxhR xWfCAQD4MFLtNZKDYyk7aRzUt9x2u0oqC6PSBAxdUVwIJBgHjgD/Tn7i8wku0mnd T6Kr0Z9f0VN/3OjiJp0VJrjsWhKJcgg= =RQlU -----END PGP SIGNATURE----- --dwa3ea6vcaiywqfz-- --===============0742434945360607808== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel --===============0742434945360607808==--