From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King - ARM Linux Subject: Re: [PATCH 0/3] Deterministic UART numbering on Samsung SoCs Date: Thu, 26 Jun 2014 12:39:39 +0100 Message-ID: <20140626113939.GP32514@n2100.arm.linux.org.uk> References: <1403781875-5425-1-git-send-email-t.figa@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1403781875-5425-1-git-send-email-t.figa@samsung.com> Sender: linux-samsung-soc-owner@vger.kernel.org To: Tomasz Figa Cc: linux-samsung-soc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, devicetree@vger.kernel.org, Kukjin Kim , Marek Szyprowski , Rob Herring , Mark Rutland , Greg Kroah-Hartman , Jiri Slaby , Daniel Drake , Tomasz Figa List-Id: devicetree@vger.kernel.org On Thu, Jun 26, 2014 at 01:24:32PM +0200, Tomasz Figa wrote: > Current Samsung UART driver relies on probe order of particular > samsung-uart instances, which makes it impossible to get proper > initialization of ports when not all ports are available on board, > not even saying of deterministic device naming. > > This series intends to fix this situation by adding support to parse > aliases from device tree and use them to assign instance IDs to > particular port instances. How about instead exporting the path/id information so that userspace can create /dev/serial/by-{path,id}/... for internal devices instead? The problem you're raising is very much the same problem you have when there are multiple USB serial devices connected to the machine - you just get a bunch of /dev/ttyUSB* devices which are unordered (they can change on each boot, or change order if you disconnect and reconnect them.) /dev/serial/by-{path,id}/ allows for a much more stable path. -- FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly improving, and getting towards what was expected from it.