From: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
To: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
Steven Rostedt <rostedt@goodmis.org>,
Stephen Boyd <sboyd@kernel.org>
Cc: Joel Fernandes <joel@joelfernandes.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Andy Gross <andy.gross@linaro.org>,
David Brown <david.brown@linaro.org>,
Jiri Slaby <jslaby@suse.com>, Kees Cook <keescook@chromium.org>,
Geliang Tang <geliangtang@gmail.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Pramod Gurav <gpramod@codeaurora.org>,
linux-arm-msm@vger.kernel.org, linux-soc@vger.kernel.org,
linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org,
Rajendra Nayak <rnayak@codeaurora.org>,
Vivek Gautam <vivek.gautam@codeaurora.org>,
Sibi Sankar <sibis@codeaurora.org>
Subject: Re: Crash in msm serial on dragonboard with ftrace bootargs
Date: Thu, 15 Nov 2018 16:03:29 +0530 [thread overview]
Message-ID: <8f65f83b-8cd9-5e35-c324-30b86390906e@codeaurora.org> (raw)
In-Reply-To: <38099043-f5ed-6d81-bf94-13f61cfa8507@linaro.org>
On 11/13/2018 3:14 PM, Srinivas Kandagatla wrote:
> Hi Sai,
>
>
>
> On 25/10/18 15:36, saiprakash.ranjan@codeaurora.org wrote:
>> "If I disable dma node and LS-UART0, then I don't see any crash and
>> ftrace also works fine"
>>
>> And one more observation is that even without ftrace cmdline, if I use
>> earlycon and disable dma, I face the same crash.
>>
>> So basically this seems to be some kind of earlycon and dma issue and
>> not ftrace(I can be wrong).
>>
>> So adding Srinivas for more info on this dma node.
>
> Its Interesting that my old email conversations with SBoyd show that I
> have investigated this issue in early 2016!
>
> My analysis so far:
>
> This reason for such behavior is due the common iface clock
> (GCC_BLSP1_AHB_CLK) across multiple drivers(serial ports, bam dma
> and other low speed devices).
> The code flow in DB410C is bit different, as the uart0 is first
> attempted to set as console and then uart1, this ordering triggers
> pm state change uart_change_pm(state, UART_PM_STATE_OFF) from serial
> core while setting up uart0, this would go and disable all the
> clocks for uart0.
> As uart1 is not setup Yet, and earlycon is still active, any
> attempts by earlycon to write to registers would trigger a system
> reboot as the clock was just disabled by uart0 change_pm code.
>
> This can even be triggered with any drivers like spi which uses same
> clock I guess.
>
> Hope it helps,
>
> Either earlycon needs to reference the clocks or those clocks needs to
> be marked always-on (but only with earlycon).
>
>>
>> Also just for a note: apq8096-db820c.dtsi shows UART0 is disabled because
>> bootloader does not allow access to it. Could this also be the case
>> for db410c?
> No, this is not the case with DB410c. DB820c has added restrictions in
> TZ, I think new booloaders should have solved this issue.
>
>
Hi Srinivas,
Thanks a lot for pointing out the cause of crash.
I just tried setting GCC_BLSP1_AHB_CLK with flag CLK_IS_CRITICAL and the
crash disappears.
But I suppose setting CLK_IS_CRITICAL is not the solution?
Thanks,
Sai
--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation
next prev parent reply other threads:[~2018-11-15 10:33 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-16 11:38 Crash in msm serial on dragonboard with ftrace bootargs Sai Prakash Ranjan
2018-10-16 11:44 ` Greg Kroah-Hartman
2018-10-16 11:58 ` Sai Prakash Ranjan
2018-10-16 15:29 ` Steven Rostedt
2018-10-16 16:35 ` Sai Prakash Ranjan
2018-10-16 16:57 ` Steven Rostedt
2018-10-16 17:36 ` Sai Prakash Ranjan
2018-10-16 17:48 ` Steven Rostedt
2018-10-16 18:05 ` Sai Prakash Ranjan
2018-10-16 18:16 ` Steven Rostedt
2018-10-16 18:25 ` Sai Prakash Ranjan
2018-10-16 18:41 ` Steven Rostedt
2018-10-16 19:01 ` Sai Prakash Ranjan
2018-10-16 19:03 ` Steven Rostedt
2018-10-16 19:06 ` Sai Prakash Ranjan
2018-10-16 19:15 ` Steven Rostedt
2018-10-16 19:16 ` Steven Rostedt
2018-10-16 19:37 ` Sai Prakash Ranjan
2018-10-16 19:35 ` Sai Prakash Ranjan
2018-10-16 20:51 ` Stephen Boyd
2018-10-17 11:27 ` Sai Prakash Ranjan
2018-10-18 2:33 ` Steven Rostedt
2018-10-18 5:21 ` Sai Prakash Ranjan
2018-10-18 13:17 ` Steven Rostedt
2018-10-19 4:17 ` Joel Fernandes
2018-10-19 6:54 ` Sai Prakash Ranjan
2018-10-19 13:51 ` Steven Rostedt
2018-10-19 14:48 ` Sai Prakash Ranjan
2018-10-19 15:12 ` Steven Rostedt
2018-10-25 14:36 ` saiprakash.ranjan
2018-11-13 9:44 ` Srinivas Kandagatla
2018-11-15 10:33 ` Sai Prakash Ranjan [this message]
2018-11-15 10:53 ` Srinivas Kandagatla
2018-11-16 3:39 ` Viresh Kumar
2018-11-16 10:49 ` Sai Prakash Ranjan
2018-10-16 17:02 ` Kees Cook
2018-10-17 10:13 ` Joel Fernandes
2018-10-17 11:38 ` Sai Prakash Ranjan
2018-10-17 14:49 ` Sai Prakash Ranjan
2018-10-17 17:56 ` Joel Fernandes
2018-10-17 18:25 ` Kees Cook
2018-10-16 23:09 ` Joel Fernandes
2018-10-17 11:53 ` Sai Prakash Ranjan
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