linux-kernel - Re: [RFC] With 8250 Designware UART, if writes to the LCR failed the kernel will hung up

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAD7vxxJvL61BjD9AMBF34Y8xnY+D-umuWLUq8Dh7ZbSm5tCE9w@mail.gmail.com>
Date:	Mon, 9 Mar 2015 07:36:21 -0700
From:	Tim Kryger <tim.kryger@...il.com>
To:	Alan Cox <alan@...ux.intel.com>
Cc:	"long.wanglong" <long.wanglong@...wei.com>,
	Peter Hurley <peter@...leysoftware.com>,
	Zhang Zhen <zhenzhang.zhang@...wei.com>,
	linux-serial@...r.kernel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Tim Kryger <tim.kryger@...aro.org>, gregkh@...uxfoundation.org,
	Jamie Iles <jamie@...ieiles.com>,
	Arnd Bergmann <arnd@...db.de>, shenjiangjiang@...wei.com,
	Wang Kai <morgan.wang@...wei.com>
Subject: Re: [RFC] With 8250 Designware UART, if writes to the LCR failed the
 kernel will hung up

On Mon, Mar 9, 2015 at 6:32 AM, Alan Cox <alan@...ux.intel.com> wrote:
>> Maybe the next release of the board we will upgrade the serial block to the new version.
>> but the issue is that how we circumvent this problem in kernel?
>
> What is the official vendor workaround ?

They introduced a UART_16550_COMPATIBLE option for the IP which should
be selected.

If configured, writes to the LCR are allowed even if it is "busy" so
there is no need to retry.

More importantly there is no possibility of failing to write the LCR
after numerous retries.

-Tim
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/