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From: Brijesh Singh <brijesh.singh@amd.com>
To: Laszlo Ersek <lersek@redhat.com>,
	edk2-devel-01 <edk2-devel@lists.01.org>
Cc: brijesh.singh@amd.com, Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Heyi Guo <guoheyi@huawei.com>, Star Zeng <star.zeng@intel.com>
Subject: Re: [PATCH 1/1] ArmVirtPkg/FdtPL011SerialPortLib: call PL011UartLib in all SerialPortLib APIs
Date: Wed, 16 Aug 2017 10:03:36 -0500	[thread overview]
Message-ID: <cdffe484-b7d6-e807-7c03-e71580bee484@amd.com> (raw)
In-Reply-To: <20170816121040.15757-2-lersek@redhat.com>

Hi Laszlo,

Thanks for the patch.


On 08/16/2017 07:10 AM, Laszlo Ersek wrote:
> With the SerialDxe change in commit 4cf3f37c87ba ("MdeModulePkg SerialDxe:
> Process timeout consistently in SerialRead", 2017-07-18), setting
> EFI_SERIAL_INPUT_BUFFER_EMPTY in the "Control" output parameter, in the
> GetControl() SerialPortLib function, is no longer a "small optimization".
> Namely, due to the SerialDxe change, the GetOneKeyFromSerial() call in
> TerminalDxe's TerminalConInTimerHandler() can take very long if the input
> queue is empty, even if GetOneKeyFromSerial()'s return value causes the
> loop to be exited right after, in the first iteration.
> 
> This issue causes a boot hang in ArmVirtQemu: with the input queue empty,
> TerminalConInTimerHandler() takes so long to return that, by the time it
> returns, there's another execution queued already (due to the associated
> timer event being signaled meanwhile). The boot process is stuck in the
> timer event handler.
> 
> Therefore even the first GetOneKeyFromSerial() iteration must be prevented
> in TerminalConInTimerHandler() if the input queue is empty, and that
> requires implementing GetControl() for real.
> 
> Implement the SetAttributes(), SetControl() and GetControl() APIs (of
> SerialPortExtLib origin) in FdtPL011SerialPortLib with calls to matching
> PL011UartLib functions. This follows the example of
> "ArmPlatformPkg/Library/PL011SerialPortLib" and also matches Star's
> original idea under [1].
> 
> The patch can be considered a continuation of commit ad7f6bc2e116
> ("ArmVirtPkg: Use SerialDxe in MdeModulePkg instead of EmbeddedPkg",
> 2015-11-26), based on the mailing list threads [1] [2] [3].
> 
> [1] http://mid.mail-archive.com/1447752930-32880-12-git-send-email-star.zeng@intel.com
> [2] http://mid.mail-archive.com/1448243067-1880-12-git-send-email-star.zeng@intel.com
> [3] http://mid.mail-archive.com/b748580c-cb51-32c9-acf9-780841ef15da@redhat.com
> 
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Cc: Brijesh Singh <brijesh.singh@amd.com>
> Cc: Heyi Guo <guoheyi@huawei.com>
> Cc: Star Zeng <star.zeng@intel.com>
> Originally-suggested-by: Star Zeng <star.zeng@intel.com>
> Reported-by: Brijesh Singh <brijesh.singh@amd.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Laszlo Ersek <lersek@redhat.com>
> ---


I can confirm that with this patch I am able to boot to the UEFI shell prompt.

Tested-by: Brijesh Singh <brijesh.singh@amd.com>



  parent reply	other threads:[~2017-08-16 15:01 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-16 12:10 [PATCH 0/1] ArmVirtPkg/FdtPL011SerialPortLib: call PL011UartLib in all SerialPortLib APIs Laszlo Ersek
2017-08-16 12:10 ` [PATCH 1/1] " Laszlo Ersek
2017-08-16 14:42   ` Ard Biesheuvel
2017-08-16 15:03   ` Brijesh Singh [this message]
2017-08-16 15:36     ` Laszlo Ersek
2017-08-17  1:02   ` Zeng, Star
2017-08-17 12:17     ` Laszlo Ersek

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