linux-kernel - Re: [PATCH] boot_constraint: Add constraints for earlycon on dragonboard 410c

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Message-ID: <20181116105317.5zpbzhgt5cnssuki@vireshk-i7>
Date:   Fri, 16 Nov 2018 16:23:17 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
Cc:     Viresh Kumar <vireshk@...nel.org>, srinivas.kandagatla@...aro.org,
        Stephen Boyd <sboyd@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Rob Herring <robh+dt@...nel.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Vivek Gautam <vivek.gautam@...eaurora.org>,
        Sibi Sankar <sibis@...eaurora.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH] boot_constraint: Add constraints for earlycon on
 dragonboard 410c

Hi,

On 16-11-18, 16:16, Sai Prakash Ranjan wrote:
> iface clock is shared with other drivers, which may reconfigure
> this before the serial driver comes up. This may lead to
> crashes like the one below where GCC_BLSP1_AHB_CLK is same across
> multiple drivers like bam dma.
> 
> <0>[    3.164471] Internal error: synchronous external abort: 96000010 [#1] PREEMPT SMP
> <4>[    3.164479] Modules linked in:
> <4>[    3.164495] CPU: 2 PID: 1 Comm: swapper/0 Not tainted 4.19.0-rc8-00008-ge033b9909fff-dirty #175
> <4>[    3.164501] Hardware name: Qualcomm Technologies, Inc. APQ 8016 SBC (DT)
> <4>[    3.164508] pstate: 40000085 (nZcv daIf -PAN -UAO)
> <4>[    3.164514] pc : msm_read.isra.2+0x20/0x50
> <4>[    3.164520] lr : msm_read.isra.2+0x1c/0x50
> <4>[    3.164526] sp : ffff000008033a50
> <4>[    3.164531] x29: ffff000008033a50 x28: ffff000009486018
> <4>[    3.164548] x27: 0000000000000001 x26: ffff7dfffe7ff070
> <4>[    3.164565] x25: 0000000000000034 x24: ffff000009486000
> <4>[    3.164582] x23: 0000000000000000 x22: ffff00000978e190
> <4>[    3.164599] x21: ffff0000095e8228 x20: 0000000000000034
> <4>[    3.164616] x19: ffff7dfffe7ff008 x18: ffffffffffffffff
> <4>[    3.164632] x17: 0000000000000000 x16: 0000000000000000
> <4>[    3.164649] x15: ffff0000094a96c8 x14: ffff00008978e6bf
> <4>[    3.164666] x13: ffff00000978e6cd x12: 0000000000000038
> <4>[    3.164683] x11: ffff0000094c6000 x10: 0000000000000c24
> <4>[    3.164699] x9 : ffff80003c89b400 x8 : ffff000008033970
> <4>[    3.164716] x7 : ffff80000eb04100 x6 : 00000000000af304
> <4>[    3.164732] x5 : 0000000000000c40 x4 : ffff80003c06f000
> <4>[    3.164750] x3 : ffff80003c89b498 x2 : 0000000000000000
> <4>[    3.164766] x1 : ffff80003ca68000 x0 : 0000000000000800
> <0>[    3.164785] Process swapper/0 (pid: 1, stack limit = 0x(____ptrval____))
> <4>[    3.164791] Call trace:
> <4>[    3.164797]  msm_read.isra.2+0x20/0x50
> <4>[    3.164804]  msm_reset_dm_count+0x44/0x80
> <4>[    3.164810]  __msm_console_write+0x1c8/0x1d0
> <4>[    3.164816]  msm_serial_early_write_dm+0x3c/0x50
> <4>[    3.164823]  console_unlock.part.6+0x468/0x528
> <4>[    3.164829]  vprintk_emit+0x210/0x218
> <4>[    3.164835]  vprintk_default+0x48/0x58
> <4>[    3.164841]  vprintk_func+0xf0/0x1c0
> <4>[    3.164847]  printk+0x74/0x94
> <4>[    3.164853]  sci_init+0x24/0x3c
> <4>[    3.164859]  do_one_initcall+0x54/0x248
> <4>[    3.164866]  kernel_init_freeable+0x210/0x378
> <4>[    3.164872]  kernel_init+0x18/0x118
> <4>[    3.164878]  ret_from_fork+0x10/0x1c
> <0>[    3.164884] Code: aa1e03e0 8b214273 97e616f7 d503201f (b9400260)
> 
> Link: https://lore.kernel.org/lkml/1cae8f10-55f5-20ce-9105-30af6f88bd6e@codeaurora.org/
> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
> 
> ---
> 
> This is purely dependent on boot constraint subsystem by Viresh.
> 
> Link: https://lore.kernel.org/lkml/cover.1519380923.git.viresh.kumar@linaro.org/
> ---
>  drivers/soc/qcom/boot_constraint.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)

Nice to see that the new subsystem has fixed your issue as well and
thanks for the patch. I am afraid though that this patch isn't going
to get merged anywhere as the subsystem isn't merged yet as Greg
wasn't too confident [1] about it. We are looking for more use-cases
apart from earlycon and clcd.

Thanks.

--
viresh

[1] lore.kernel.org/lkml/20180323150420.GA21152@...ah.com