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

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Date:   Fri, 16 Nov 2018 16:16:07 +0530
From:   Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
To:     Viresh Kumar <vireshk@...nel.org>, srinivas.kandagatla@...aro.org,
        Stephen Boyd <sboyd@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        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>
Cc:     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,
        Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
Subject: [PATCH] boot_constraint: Add constraints for earlycon on dragonboard 410c

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(+)

diff --git a/drivers/soc/qcom/boot_constraint.c b/drivers/soc/qcom/boot_constraint.c
index ca01eb50d9a9..c4e580a118f0 100644
--- a/drivers/soc/qcom/boot_constraint.c
+++ b/drivers/soc/qcom/boot_constraint.c
@@ -49,6 +49,10 @@ static struct dev_boot_constraint_supply_info vddio_info = {
 	.name = "vddio"
 };
 
+static struct dev_boot_constraint_clk_info uart_iface_clk_info = {
+	.name = "iface",
+};
+
 static struct dev_boot_constraint constraints_mdss[] = {
 	{
 		.type = DEV_BOOT_CONSTRAINT_PM,
@@ -92,6 +96,13 @@ static struct dev_boot_constraint constraints_dsi[] = {
 	},
 };
 
+static struct dev_boot_constraint constraints_uart[] = {
+	{
+		.type = DEV_BOOT_CONSTRAINT_CLK,
+		.data = &uart_iface_clk_info,
+	},
+};
+
 static struct dev_boot_constraint_of constraints[] = {
 	{
 		.compat = "qcom,mdss",
@@ -105,6 +116,10 @@ static struct dev_boot_constraint_of constraints[] = {
 		.compat = "qcom,mdss-dsi-ctrl",
 		.constraints = constraints_dsi,
 		.count = ARRAY_SIZE(constraints_dsi),
+	}, {
+		.compat = "qcom,msm-uartdm-v1.4",
+		.constraints = constraints_uart,
+		.count = ARRAY_SIZE(constraints_uart),
 	},
 };
 
-- 
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