Tkanks a lot!<br><br>On Wednesday, March 2, 2016, <<a href="mailto:victorascroft@gmail.com">victorascroft@gmail.com</a>> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi,<br>
<br>
On 16-03-01 21:07:09, Woody Wu wrote:<br>
> On Friday, February 26, 2016, <<a href="javascript:;" onclick="_e(event, 'cvml', 'victorascroft@gmail.com')">victorascroft@gmail.com</a>> wrote:<br>
><br>
> > Hi,<br>
> ><br>
> > On 16-02-26 00:55:40, Woody Wu wrote:<br>
> > > Hi,<br>
> > ><br>
> > > It seems, at least in 4.4.2 kernel, earlyprintk parameter supports<br>
> > > something like 's3c24xx,<addr>'. But I dont know where to find out the<br>
> > addr<br>
> > > value of the first uart port on my *s3c2416* based board. Can someone<br>
> > > please tell me?<br>
> > ><br>
> > > Also, I desire to know if the earlycon parameter supports the Samsung<br>
> > > S3C24xx uarts, if so, what should the value of the parameter look like?<br>
> ><br>
> > Have a look in the documentation here<br>
> > <a href="https://www.kernel.org/doc/Documentation/kernel-parameters.txt" target="_blank">https://www.kernel.org/doc/Documentation/kernel-parameters.txt</a><br>
> ><br>
> > The kernels kernel-parameter.txt documentation file lists the supported<br>
> > drivers.<br>
> ><br>
> > Generally the UART0 port is used for debugging but I guess there is<br>
> > no such hard and fast rule.<br>
> ><br>
> > For your particular board, you can check which UART port is used<br>
> > as the debug serial console and then get the address for the concerned<br>
> > UART by checking the relevant dtsi file in<br>
> > arch/arm/boot/dts/s3c24xx.dtsi or perhaps one of the exynosX.dtsi files?<br>
> ><br>
> > UART0 port seems to have address of 0x50000000?<br>
> ><br>
> > Regards,<br>
> > Sanchayan.<br>
><br>
><br>
> Thanks for you pointing me to the dtsi files, very informational ! And,<br>
> yes, the uart0 address os 0x50000000 and I has made it work via<br>
> 'earlyprintk=serial,0x50000000,115200'. By the way, is this a physical<br>
> address or mmap-ed address?<br>
<br>
The addresses specified in the DTS files are always physical addresses. So<br>
0x50000000 is a physical address. This address will be mapped using one of<br>
the ioremap calls by the driver and used further by kernel using readl/writel<br>
calls.<br>
<br>
You can see the earlycon support declaration here<br>
<a href="http://lxr.free-electrons.com/source/drivers/tty/serial/samsung.c#L2452" target="_blank">http://lxr.free-electrons.com/source/drivers/tty/serial/samsung.c#L2452</a><br>
<br>
s3c24xx_serial_probe<br>
-->s3c24xx_serial_init_port<br>
---->Call to devm_ioremap<br>
<br>
<a href="http://lxr.free-electrons.com/source/drivers/tty/serial/samsung.c#L1705" target="_blank">http://lxr.free-electrons.com/source/drivers/tty/serial/samsung.c#L1705</a><br>
<br>
- Sanchayan.<br>
<br>
<br>
><br>
> ><br>
> > ><br>
> > > Thank in advance,<br>
> > ><br>
> > > -woody<br>
> > ><br>
> > ><br>
> > > --<br>
> > > Life is the only flaw in an otherwise perfect nonexistence<br>
> > > -- Schopenhauer<br>
> > ><br>
> > > woody<br>
> > > public key at <a href="http://subkeys.pgp.net:11371" target="_blank">http://subkeys.pgp.net:11371</a> (<a href="javascript:;" onclick="_e(event, 'cvml', 'narkewoody@gmail.com')">narkewoody@gmail.com</a><br>
> > <javascript:;>)<br>
> ><br>
> > > _______________________________________________<br>
> > > Kernelnewbies mailing list<br>
> > > <a href="javascript:;" onclick="_e(event, 'cvml', 'Kernelnewbies@kernelnewbies.org')">Kernelnewbies@kernelnewbies.org</a> <javascript:;><br>
> > > <a href="http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies" target="_blank">http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies</a><br>
> ><br>
> ><br>
><br>
> --<br>
> Life is the only flaw in an otherwise perfect nonexistence<br>
> -- Schopenhauer<br>
><br>
> woody<br>
> public key at <a href="http://subkeys.pgp.net:11371" target="_blank">http://subkeys.pgp.net:11371</a> (<a href="javascript:;" onclick="_e(event, 'cvml', 'narkewoody@gmail.com')">narkewoody@gmail.com</a>)<br>
</blockquote><br><br>-- <br>Life is the only flaw in an otherwise perfect nonexistence<br> -- Schopenhauer<br><br>woody<br>public key at <a href="http://subkeys.pgp.net:11371">http://subkeys.pgp.net:11371</a> (<a href="mailto:narkewoody@gmail.com">narkewoody@gmail.com</a>)<br><br><br>