Re: [PATCH 1/3] serial: 8250_early: Add earlycon support for AMD Carrizo / Stoneyridge

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hi Ricardo,

On Wed, Mar 14, 2018 at 4:54 AM Ricardo Ribalda Delgado <
ricardo.ribalda@xxxxxxxxx> wrote:

> Hi Daniel


> On Wed, Mar 14, 2018 at 1:36 AM, Daniel Kurtz <djkurtz@xxxxxxxxxxxx>
wrote:
> >
> > AMD Carrizo / Stoneyridge use a DesignWare 8250 UART that uses a 48 MHz
> > input clock.
> >
> > Allow these platforms to set up this clock by specifying a kernel
command
> > line like:
> > earlycon=amdcz,mmio32,0xfedc6000,115200


> If the port and the mode (mmio32) is always fixed, couldn't we just
> add those two into
> early_amdcz_setup?

There are multiple memory mapped UARTs on at least the one chip I am aware
of, specifying the address here chooses which port to use as the early
console.

In fact, the recommended way is to have firmware specify an ACPI SPCR table
with OEMID="AMDCZ " (see https://patchwork.kernel.org/patch/10281307/) to
configure proper access and address.  With an SPCR table in place,  the
kernel command line just becomes "earlycon", with no parameters.

-Dan
--
To unsubscribe from this list: send the line "unsubscribe linux-serial" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Kernel Newbies]     [Security]     [Netfilter]     [Bugtraq]     [Linux PPP]     [Linux FS]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Samba]     [Video 4 Linux]     [Linmodem]     [Device Mapper]     [Linux Kernel for ARM]

  Powered by Linux