Re: [PATCH v2 1/4] tty: serial: Add 8250 earlycon to support noinit option

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Mon, Feb 02, 2015 at 12:43:50AM -0500, Peter Hurley wrote:
> 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,<addr>,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

Ok, now dropped, thanks.

greg k-h