From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maxime Ripard Subject: Re: [PATCH v4 5/6] serial: 8250_dw: Add support for deferred probing Date: Tue, 15 Jul 2014 09:00:33 +0200 Message-ID: <20140715070033.GF3745@lukather> References: <1404892479-12222-1-git-send-email-wens@csie.org> <1404892479-12222-6-git-send-email-wens@csie.org> Reply-To: linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="QXO0/MSS4VvK6f+D" Return-path: Content-Disposition: inline In-Reply-To: <1404892479-12222-6-git-send-email-wens-jdAy2FN1RRM@public.gmane.org> List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , To: Chen-Yu Tsai Cc: Lee Jones , Samuel Ortiz , Rob Herring , Greg Kroah-Hartman , Emilio Lopez , Mike Turquette , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-serial-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org List-Id: devicetree@vger.kernel.org --QXO0/MSS4VvK6f+D Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jul 09, 2014 at 03:54:38PM +0800, Chen-Yu Tsai wrote: > The 8250_dw driver fails to probe if the specified clock isn't > registered at probe time. Even if a clock frequency is given, > the required clock might be gated because it wasn't properly > enabled. >=20 > This happened to me when the device is registered through DT, > and the clock was part of an MFD, the PRCM found on A31 and A23 > SoCs. Unlike core clocks that are registered with OF_CLK_DECLARE, > which happen almost immediately after the kernel starts, the > clocks are registered as sub-devices of the PRCM MFD platform > device. Even though devices are registered in the order they are > found in the DT, the drivers are registered in a different, > arbitrary order. It is possible that the 8250_dw driver is > registered, and thus associated with the device and probed, before > the clock driver is registered and probed. >=20 > 8250_dw then reports unable to get the clock, and fails. Without > a working console, the kernel panics. >=20 > This patch adds support for deferred probe handling for the clock > and reset controller. >=20 > Signed-off-by: Chen-Yu Tsai Acked-by: Maxime Ripard Thanks! Maxime --=20 Maxime Ripard, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com --QXO0/MSS4VvK6f+D Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJTxNGRAAoJEBx+YmzsjxAgPw8QAIN0tPNzUK9p+PH0UZ14T813 g6BCLztYWJueJ/tCsa3ZepX/JljL3kMFHp0SSOydckg6U6grIcj09nLomiCo/kK1 jhyoTpzBWu1qlDJF9ljURdfNcMj90R+LJmjXyg8ri7LOuLqcVNOkUk8iwGVPtAmx Py1zteSEX4nuEXaCl34P9JdiFxbGfGZ2q7z0/6qTpDci2ATWoqg8THnrCh7+HcSW as55hkJC5aMwrc3z3tGCkpf0ekNiCyhRv8ir4ULE06oc8NrPXt+PfWkwXv186J/s TewFmhQ1Pt+GqgQTysAJIta7ViUlFRvShOJlvFwhQsOuZH5GILvQzDOnTabzw9nc KVAKQoKrefKgd4IsDxK+X2P9XlPopCYKq55yXHPL8p4H/6xbravG3gIo8pHtz1bl +Drlsmrc9AcTx1kXDXedQchl49r33bGyaVchVnVDdHBQpZnm64x00gpj22ilxQoQ rFW+uf8J/Yy/PEH73hUHOklWk+Q1ga1MHS90bHth3AE3VCMm3rldjBlNBRW/pR1a CvYJnakKKwrTbsOamaZVshL/kfsuNkjPp6/LzOVIQmKwWCuw8NAEdrikZNIjB2+Q uoHpyft6vOJacAgn7037SU5J7Zs765LTmb/A+S5bipyNRIMNTcXZSDgDfQXD9HYe Ac+ftTj2TApLNDJYpiCx =HtMF -----END PGP SIGNATURE----- --QXO0/MSS4VvK6f+D--