From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Hurley Subject: Re: [PATCH v2 1/4] tty: serial: Add 8250 earlycon to support noinit option Date: Mon, 02 Feb 2015 00:43:50 -0500 Message-ID: <54CF0E96.10703@hurleysoftware.com> References: <1421068104-30463-1-git-send-email-eddie.huang@mediatek.com> <1421068104-30463-2-git-send-email-eddie.huang@mediatek.com> <54CE53F3.5040709@hurleysoftware.com> <54CE6FD9.5030606@hurleysoftware.com> <1422846994.5512.25.camel@mtksdaap41> <54CEF2C8.1050808@hurleysoftware.com> <20150202042843.GA24765@kroah.com> <54CF07F3.2040100@hurleysoftware.com> <20150202052423.GA3346@kroah.com> <1422855202.26131.31.camel@mtksdaap41> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1422855202.26131.31.camel@mtksdaap41> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Eddie Huang , Greg Kroah-Hartman Cc: Rob Herring , Mark Rutland , Matthias Brugger , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Vladimir Murzin , srv_heupstream-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org, Pawel Moll , Ian Campbell , Catalin Marinas , Jonathan Corbet , Will Deacon , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, yh.chen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org, Howard Chen , Ashwin Chaugule , linux-serial-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Kumar Gala , "Joe.C" , Jiri Slaby , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Alan Cox List-Id: devicetree@vger.kernel.org On 02/02/2015 12:33 AM, Eddie Huang wrote: > Hi Peter, > > On Sun, 2015-02-01 at 21:24 -0800, Greg Kroah-Hartman wrote: >> On Mon, Feb 02, 2015 at 12:15:31AM -0500, Peter Hurley wrote: >>> On 02/01/2015 11:28 PM, Greg Kroah-Hartman wrote: >>>> On Sun, Feb 01, 2015 at 10:45:12PM -0500, Peter Hurley wrote: >>>>> On 02/01/2015 10:16 PM, Eddie Huang wrote: >>> >>>>> I'll respin proper patches on top of Greg's tty-testing branch with reverts >>>>> for the noinit options. I noticed that one of the noinit patches actually >>>>> has the linkage for the mtk earlycon, so I'll be sure to preserve that. >>>> >>>> I can just drop the patches in the tty-testing branch, that's what it is >>>> there for :) >>>> >>>> Just let me know the specific patches and I will do so, thanks. >>> >>> Well that pretty much means dropping the 3 patches that add earlycon to >>> 8250_mtk and then applying my patch (needs fixed to apply cleanly, which >>> I can do) and then applying a fixed-up replacement patch to add earlycon >>> to 8250_mtk (which I can also supply). >>> >>> Is that the way you want to go? >> >> Sounds good to me, send your patch, and I'll fix it all up tomorrow. >> >> thanks, >> >> greg k-h > > Actually, your patch is a little different from my original idea. > Although my use case only care about divisor now, but other hardware > setting is still hard-code, not from parameter. In init_port() > function: > serial8250_early_out(port, UART_LCR, 0x3); /* 8n1 */ > serial8250_early_out(port, UART_IER, 0);/* no interrupt */ > serial8250_early_out(port, UART_FCR, 0); /* no fifo */ > serial8250_early_out(port, UART_MCR, 0x3); /* DTR + RTS */ > > This is why I propose a new option "noinit". > > After checking further, in my case, I found that your patch should be > unnecessary because if skip baudrate, probe_baud() read DLL/DLM register > and init_port() write the same DLL/DLM value back, no touch any high > speed register, which means keep uart divisor setting as loader > > Since I don't take "console=uart,mmio32,,noinit" into > consideration, it is good to drop my patches in the tty-testing branch. > For my case, I can send another series without noinit, just 8250_mtk.c > and its linkage modification in 8250_early.c Ok. Greg, The patches to drop from tty-testing are: * 405017d Document: Modify 8250 earlycon kernel parameters * 0dff3a4 tty: serial: 8250_mtk: Add earlycon * b829735 tty: serial: Add 8250 earlycon to support noinit option 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