From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sebastian Frias Subject: Re: [RFC PATCH] always probe UART HW when options are not specified Date: Mon, 18 Jan 2016 12:52:51 +0100 Message-ID: <569CD213.9020009@laposte.net> References: <5672D18E.8000301@laposte.net> <5672E2CF.6080705@hurleysoftware.com> <5672E76A.3010506@laposte.net> <5672F588.8070503@hurleysoftware.com> <5672FD35.5070609@laposte.net> <56731689.70702@hurleysoftware.com> <56740FC3.50302@laposte.net> <5674204C.1000907@hurleysoftware.com> <56782DE5.7090708@laposte.net> <56798EC7.1030804@laposte.net> <5693C52B.90003@laposte.net> <5693D41E.8050601@hurleysoftware.com> <5693ECBA.50003@laposte.net> <5693FD3C.5080601@hurleysoftware.com> <5694C94B.3090405@free.fr> <56950C21.3010805@laposte.net> <5695584E.3040902@hurleysoftware.com> <5696317C.4020709@laposte.net> <56967C7F.4060705@hurleysoftware.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <56967C7F.4060705@hurleysoftware.com> Sender: linux-kernel-owner@vger.kernel.org To: Peter Hurley Cc: Mason , Greg Kroah-Hartman , linux-serial@vger.kernel.org, LKML , Mans Rullgard List-Id: linux-serial@vger.kernel.org Hi Peter, On 01/13/2016 05:34 PM, Peter Hurley wrote: > On 01/13/2016 03:14 AM, Sebastian Frias wrote: >> Hi Peter, >> >> On 01/12/2016 08:47 PM, Peter Hurley wrote: >>> On 01/12/2016 06:22 AM, Sebastian Frias wrote: >>>> >>>> For the record, I'm using a SoC emulator, and thus do not have a bootloader per se and there are a bunch of other things that I cannot count on. >>>> The emulator has the UART pre-setup, so I just need Linux to take over without changing the parameters. >>>> Ideally, I would like to have the same image of Linux+DT to start in any instance of the emulator or real chips, regardless of the clock ratios, that's why I sort of need Linux to not change the UART speed, which is quite tricky because there are no clock generators in the emulator. >>> >>> Got it, thanks for the info. >>> Please test the series I just cc'd you on plus the patch I sent >>> you yesterday. >>> >>> That should get you an earlycon up and running on that simulator; >>> let me know if it doesn't and we'll go from there. >> >> Ok, thanks. >> I will try as soon as we finish rebasing our changes on top of >> "mainline" (or HEAD, or is it "-next"? I don't know how you guys call >> the most recent code base for Linux) > > The basic tree organization is > > Linus's tree <---- linux-next[date] <----- maintainers' trees > (mainline) (next) (eg., Greg's tty tree) > > The patches I sent you (along with any required modifications during the > review cycle) are based on the tty-next branch in Greg's tty tree here > git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git > > As of this email, Greg's tree is based on Linus's 4.4-rc6 which should > be stable enough for you to test these patches on. Thanks for your explanation :-) > >> Actually, I tried yesterday on a 4.1.13 but >> "[drivers/tty/serial/earlycon.c:62] earlycon_map()" was still the >> last message I got, just as with the OF_EARLYCON_DECLARE hack I had >> previously talk about, and so I would like to test on the same >> conditions than you, mainline. > > So just to confirm, you applied "8250: Add Au1x00/RT288x earlycon support" > to 4.1.13 and the earlycon didn't come up when you used the kernel > command line option like so: > > earlycon=rt288x,mmio32,0x10700 > > Is that correct? > Sort of, I applied your patch "8250: Add Au1x00/RT288x earlycon support", and then tried with something like: aliases { serial0 = &uart; }; chosen { bootargs = "earlycon console mem=256M earlyprintk debug ignore_loglevel"; stdout-path = "serial0:115200n8"; }; uart: serial@10700 { compatible = "ralink,rt2880-uart"; reg = <0x10700 0x30>; interrupts = <1 IRQ_TYPE_LEVEL_HIGH>; clock-frequency = <7372800>; reg-shift = <2>; }; I can see that the code is correctly picking up the rt288x from the DT (I put logs): ... [drivers/of/fdt.c:834] early_init_dt_scan_chosen_serial(): 'ralink,rt2880-uart' [drivers/tty/serial/earlycon.c:239] of_setup_earlycon(): addr=00010700 setup@c024c14c [drivers/tty/serial/earlycon.c:62] earlycon_map(): paddr 0x00010700 size 4096 (last log visible on UART) where 0xc024c14c resolves to 'early_rt288x_setup' from your patch (in the disassembly) This happens when parsing the first token of the bootargs, "earlycon". I will let you know how it goes the tests on 4.4. Best regards, Sebastian