Hi Ard
> -----Original Message-----
> From: Ard Biesheuvel <ard.biesheu...@linaro.org>
> Sent: Monday, December 3, 2018 7:35 PM
> To: Laszlo Ersek <ler...@redhat.com>
> Cc: Udit Kumar <udit.ku...@nxp.com>; Andrew Fish <af...@apple.com>; Leif
> Lindholm <leif.lindh...@linaro.org>; Ruiyu Ni <ruiyu...@intel.com>; edk2-
> de...@lists.01.org; Zeng, Star <star.z...@intel.com>
> Subject: Re: [edk2] Help on boot manager 'Boot Manager Menu' and direct boot
>
> On Mon, 3 Dec 2018 at 14:45, Laszlo Ersek <ler...@redhat.com> wrote:
> >
> > On 12/03/18 11:03, Udit Kumar wrote:
> > > Hi Laszlo
> > >
> > >> Are you using the latest edk2?
> > > Yes, when I hit the bug, first step was to move to latest edk2. But this
> > > didn't
> helped.
> > >
> > > I am not sure, why we are keeping PL011 Fifo mode off in default
> configuration.
> >
> > Sorry, I don't know: although the subject logic has gone through
> > several updates over time, the default that you point out seems to go
> > back to commit 051e63bb551a ("ArmPlatformPkg/PL011Uart: Allowed to
> > change UART settings in its initialization function", 2012-02-29). And
> > that commit doesn't explain the default.
> >
>
> The default setting for
> gEfiMdePkgTokenSpaceGuid.PcdUartDefaultReceiveFifoDepth is 1 not 0, and so
> you will end up with a 1 character FIFO setting. I wonder if we could improve
Setting this Pcd to zero will fix problem for me,
With PcdUartDefaultReceiveFifoDepth as 1, we are disabling the Fifo at IP
level whereas for 0 we are enabling IP fifo.
> PL011UartInitializePort () in PL011UartLib to deal with this better.
Suggest, if IP level Fifo can be kept enabled, always ?
> Note that this also affects platforms that can switch between DT and ACPI
> boot:
> the same PL011 is described as a 'dumb' SBSA uart in the latter case, and so
> it is
> up to the firmware to configure the UART FIFO correctly, or you will not be
> able
> to use the UART under the ACPI OS.
For my ACPI boot (without SPCR table), I hit the same issue.
OS (Linux, not sure of other OSes) except FIFO to be enabled by
firmware/boot-loader.
Regards
Udit
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