Messages in this thread | | | Date | Thu, 17 Dec 2015 09:21:43 -0800 | From | Greg Kroah-Hartman <> | Subject | Re: [RFC PATCH] always probe UART HW when options are not specified |
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On Thu, Dec 17, 2015 at 05:48:42PM +0100, Sebastian Frias wrote: > On 12/17/2015 05:29 PM, Peter Hurley wrote: > >On 12/17/2015 07:15 AM, Sebastian Frias wrote: > >>--- > >> > >>I think there are a few minor bugs on the 8250 UART code. > >> > >>Below you can find a patch with a proposed solution. > >> > >>In a nutshell: > >>- probe_baud from 87515772c33ee8a0cc08d984a7d2401eeff074cd was > >>converted into probe_port so that it reads all the parameters that > >>uart_set_options require (namely baud, parity, bits, flow). > >>- reading/writing to UART_DLL/UART_DLM directly are converted to > >>using the read_dl/write_dl callbacks. > >>- the port is always probed if there are no options (*). > > > >Because I don't want to probe the port at all. > > > >But must when using the > > earlycon=ttyS0,.... > > > >command-line (because the original hack expects that behavior). > > Ok, we are using: > > "console=ttyS0 earlyprintk" > > and the 8250 (with CONFIG_SERIAL_8250_RT288X=y) driver. > > The hardware is setup prior to Linux boot. > We don't want Linux to change the UART settings, just to pick up whatever > settings the UART has and take over UART.
Don't do that :) Linux can't "know" what happened before it started to the hardware and expect to work properly.
> How do you suggest we do that? Right now, since it does not probe, it just > messes up the UART config setup before booting Linux.
pass in the same settings as you previously set up, that way there is no change.
thanks,
greg k-h
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