From mboxrd@z Thu Jan 1 00:00:00 1970 From: maxime.ripard@free-electrons.com (Maxime Ripard) Date: Tue, 15 Jul 2014 09:00:33 +0200 Subject: [PATCH v4 5/6] serial: 8250_dw: Add support for deferred probing In-Reply-To: <1404892479-12222-6-git-send-email-wens@csie.org> References: <1404892479-12222-1-git-send-email-wens@csie.org> <1404892479-12222-6-git-send-email-wens@csie.org> Message-ID: <20140715070033.GF3745@lukather> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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. > > 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. > > 8250_dw then reports unable to get the clock, and fails. Without > a working console, the kernel panics. > > This patch adds support for deferred probe handling for the clock > and reset controller. > > Signed-off-by: Chen-Yu Tsai Acked-by: Maxime Ripard Thanks! Maxime -- Maxime Ripard, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 819 bytes Desc: Digital signature URL: