From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Hurley Subject: Re: [PATCH V3 5/7] serial: earlycon: Set UPIO_MEM32BE based on DT properties Date: Thu, 02 Apr 2015 12:15:05 -0400 Message-ID: <551D6B09.6060100@hurleysoftware.com> References: <1416872182-6440-1-git-send-email-cernekee@gmail.com> <1416872182-6440-6-git-send-email-cernekee@gmail.com> <54F3914F.3080905@hurleysoftware.com> <20150328013604.488A0C4091F@trevor.secretlab.ca> <5516DE64.6000104@hurleysoftware.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Kevin Cernekee Cc: Grant Likely , Greg KH , Jiri Slaby , Rob Herring , Arnd Bergmann , Florian Fainelli , "linux-serial-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Linux MIPS Mailing List List-Id: devicetree@vger.kernel.org On 03/28/2015 03:28 PM, Kevin Cernekee wrote: > Side note: > > AFAIK we still have a problem if somebody wants to build serial8250 + > (any other tty driver that occupies major 4 / minor 64) into the same > kernel, and use DT to pick the correct driver at runtime. Yep, exactly. > serial8250_init() starts registering ports before it knows whether the > system even has an 8250. This behavior is required to support hw configuration from userspace. > I talked to Rob about it earlier this week > and he suggested that you might have some thoughts on how to fix it. A big piece of that will land in 4.01 (once I get the actual 8250 split commit to Greg). The 8250 driver has been split into a legacy/universal 8250 driver and separate port ops module; one of the benefits of this is that the objectionable legacy behavior of the 8250 driver (especially limitations wrt ttyS sharing) can be left behind in that driver without breaking existing users. The idea is that an alternate 8250 driver(s) with none of the legacy baggage can be taught to share (4,64) ports with other drivers. Unfortunately, I haven't made further progress with because of other projects. Regards, Peter Hurley -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html