From: Zhang Zhen <zhenzhang.zhang@huawei.com>
To: Peter Hurley <peter@hurleysoftware.com>
Cc: Tim Kryger <tim.kryger@gmail.com>,
Alan Cox <alan@linux.intel.com>,
"long.wanglong" <long.wanglong@huawei.com>,
linux-serial@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
gregkh@linuxfoundation.org, Jamie Iles <jamie@jamieiles.com>,
Arnd Bergmann <arnd@arndb.de>,
shenjiangjiang@huawei.com, Wang Kai <morgan.wang@huawei.com>
Subject: Re: [RFC] With 8250 Designware UART, if writes to the LCR failed the kernel will hung up
Date: Wed, 11 Mar 2015 09:20:19 +0800 [thread overview]
Message-ID: <54FF9853.2060105@huawei.com> (raw)
In-Reply-To: <54FEF0B0.6010002@hurleysoftware.com>
On 2015/3/10 21:25, Peter Hurley wrote:
> On 03/09/2015 10:47 PM, Tim Kryger wrote:
>> The current workaround of clearing fifos and retrying a fixed number
>> of times isn't ideal but I'm not sure what else can be done given the
>> way this hardware works.
>
> But hanging the machine is not an acceptable outcome.
>
> Since the hang stems from the printk while already holding the port->lock,
> until I can fix the console write, I think it's best to comment out
> the dev_err() with a FIXME note.
Yeah，i agree.
>
> The 8250 console write already checks port->sysrq to allow printk from
> within the driver so this solution just needs to be generalized.
> And there are debug uses of printk() from within the driver that are just
> as broken, so this isn't the only use case. (I want to do something
> similar for the au_serial-* i/o accessors too).
>
> Regards,
> Peter Hurley
>
>
>
> .
>
WARNING: multiple messages have this Message-ID (diff)
From: Zhang Zhen <zhenzhang.zhang@huawei.com>
To: Peter Hurley <peter@hurleysoftware.com>
Cc: Tim Kryger <tim.kryger@gmail.com>,
Alan Cox <alan@linux.intel.com>,
"long.wanglong" <long.wanglong@huawei.com>,
<linux-serial@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
<gregkh@linuxfoundation.org>, Jamie Iles <jamie@jamieiles.com>,
Arnd Bergmann <arnd@arndb.de>, <shenjiangjiang@huawei.com>,
Wang Kai <morgan.wang@huawei.com>
Subject: Re: [RFC] With 8250 Designware UART, if writes to the LCR failed the kernel will hung up
Date: Wed, 11 Mar 2015 09:20:19 +0800 [thread overview]
Message-ID: <54FF9853.2060105@huawei.com> (raw)
In-Reply-To: <54FEF0B0.6010002@hurleysoftware.com>
On 2015/3/10 21:25, Peter Hurley wrote:
> On 03/09/2015 10:47 PM, Tim Kryger wrote:
>> The current workaround of clearing fifos and retrying a fixed number
>> of times isn't ideal but I'm not sure what else can be done given the
>> way this hardware works.
>
> But hanging the machine is not an acceptable outcome.
>
> Since the hang stems from the printk while already holding the port->lock,
> until I can fix the console write, I think it's best to comment out
> the dev_err() with a FIXME note.
Yeah，i agree.
>
> The 8250 console write already checks port->sysrq to allow printk from
> within the driver so this solution just needs to be generalized.
> And there are debug uses of printk() from within the driver that are just
> as broken, so this isn't the only use case. (I want to do something
> similar for the au_serial-* i/o accessors too).
>
> Regards,
> Peter Hurley
>
>
>
> .
>
next prev parent reply other threads:[~2015-03-11 1:20 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-06 9:11 [RFC] With 8250 Designware UART, if writes to the LCR failed the kernel will hung up Zhang Zhen
2015-03-06 9:11 ` Zhang Zhen
2015-03-06 16:50 ` Peter Hurley
2015-03-07 3:01 ` Tim Kryger
2015-03-09 7:10 ` long.wanglong
2015-03-09 7:10 ` long.wanglong
2015-03-09 13:32 ` Alan Cox
2015-03-09 14:36 ` Tim Kryger
2015-03-09 15:05 ` Alan Cox
2015-03-10 2:47 ` Tim Kryger
2015-03-10 3:15 ` Zhang Zhen
2015-03-10 3:15 ` Zhang Zhen
2015-03-10 13:25 ` Peter Hurley
2015-03-11 1:20 ` Zhang Zhen [this message]
2015-03-11 1:20 ` Zhang Zhen
2015-03-13 15:36 ` Andy Shevchenko
2015-03-15 14:50 ` Peter Hurley
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