diff mbox series

[v4,3/6] watchdog: rzg2l_wdt: Fix 'BUG: Invalid wait context'

Message ID 20220223160100.23543-4-biju.das.jz@bp.renesas.com
State Superseded
Headers show
Series RZG2L_WDT Fixes and Improvements | expand

Commit Message

Biju Das Feb. 23, 2022, 4 p.m. UTC 
This patch fixes the issue 'BUG: Invalid wait context' during restart()
callback by using clk_prepare_enable() instead of pm_runtime_get_sync()
for turning on the clocks during restart.

This issue is noticed when testing with renesas_defconfig.

[   42.213802] reboot: Restarting system
[   42.217860]
[   42.219364] =============================
[   42.223368] [ BUG: Invalid wait context ]
[   42.227372] 5.17.0-rc5-arm64-renesas-00002-g10393723e35e #522 Not tainted
[   42.234153] -----------------------------
[   42.238155] systemd-shutdow/1 is trying to lock:
[   42.242766] ffff00000a650828 (&genpd->mlock){+.+.}-{3:3}, at: genpd_lock_mtx+0x14/0x20
[   42.250709] other info that might help us debug this:
[   42.255753] context-{4:4}
[   42.258368] 2 locks held by systemd-shutdow/1:
[   42.262806]  #0: ffff80000944e1c8 (system_transition_mutex#2){+.+.}-{3:3}, at: __do_sys_reboot+0xd0/0x250
[   42.272388]  #1: ffff8000094c4e40 (rcu_read_lock){....}-{1:2}, at: atomic_notifier_call_chain+0x0/0x150
[   42.281795] stack backtrace:
[   42.284672] CPU: 0 PID: 1 Comm: systemd-shutdow Not tainted 5.17.0-rc5-arm64-renesas-00002-g10393723e35e #522
[   42.294577] Hardware name: Renesas SMARC EVK based on r9a07g044c2 (DT)
[   42.301096] Call trace:
[   42.303538]  dump_backtrace+0xcc/0xd8
[   42.307203]  show_stack+0x14/0x30
[   42.310517]  dump_stack_lvl+0x88/0xb0
[   42.314180]  dump_stack+0x14/0x2c
[   42.317492]  __lock_acquire+0x1b24/0x1b50
[   42.321502]  lock_acquire+0x120/0x3a8
[   42.325162]  __mutex_lock+0x84/0x8f8
[   42.328737]  mutex_lock_nested+0x30/0x58
[   42.332658]  genpd_lock_mtx+0x14/0x20
[   42.336319]  genpd_runtime_resume+0xc4/0x228
[   42.340587]  __rpm_callback+0x44/0x170
[   42.344337]  rpm_callback+0x64/0x70
[   42.347824]  rpm_resume+0x4e0/0x6b8
[   42.351310]  __pm_runtime_resume+0x50/0x78
[   42.355404]  rzg2l_wdt_restart+0x28/0x68
[   42.359329]  watchdog_restart_notifier+0x1c/0x30
[   42.363943]  atomic_notifier_call_chain+0x94/0x150
[   42.368732]  do_kernel_restart+0x24/0x30
[   42.372652]  machine_restart+0x44/0x70
[   42.376399]  kernel_restart+0x3c/0x60
[   42.380058]  __do_sys_reboot+0x228/0x250
[   42.383977]  __arm64_sys_reboot+0x20/0x28
[   42.387983]  invoke_syscall+0x40/0xf8

Fixes: 2cbc5cd0b55fa2 ("watchdog: Add Watchdog Timer driver for RZ/G2L")
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
---
V4:
 * New patch
---
 drivers/watchdog/rzg2l_wdt.c | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

Comments

Geert Uytterhoeven Feb. 24, 2022, 9:45 a.m. UTC | #1 
Hi Biju,

CC linux-pm

On Wed, Feb 23, 2022 at 5:01 PM Biju Das <biju.das.jz@bp.renesas.com> wrote:
> This patch fixes the issue 'BUG: Invalid wait context' during restart()
> callback by using clk_prepare_enable() instead of pm_runtime_get_sync()
> for turning on the clocks during restart.
>
> This issue is noticed when testing with renesas_defconfig.
>
> [   42.213802] reboot: Restarting system
> [   42.217860]
> [   42.219364] =============================
> [   42.223368] [ BUG: Invalid wait context ]

> Fixes: 2cbc5cd0b55fa2 ("watchdog: Add Watchdog Timer driver for RZ/G2L")
> Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>

Thanks for your patch!

> --- a/drivers/watchdog/rzg2l_wdt.c
> +++ b/drivers/watchdog/rzg2l_wdt.c

> @@ -118,7 +120,9 @@ static int rzg2l_wdt_restart(struct watchdog_device *wdev,
>
>         /* Reset the module before we modify any register */
>         reset_control_reset(priv->rstc);
> -       pm_runtime_get_sync(wdev->parent);
> +
> +       clk_prepare_enable(priv->pclk);
> +       clk_prepare_enable(priv->osc_clk);

I'm not super-happy with this circumvention of Runtime PM, but I
don't see a better option, so
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

PM: Is there a better option?

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
diff mbox series

Patch

diff --git a/drivers/watchdog/rzg2l_wdt.c b/drivers/watchdog/rzg2l_wdt.c
index 0fc73b8a9567..48dfe6e5e64f 100644
--- a/drivers/watchdog/rzg2l_wdt.c
+++ b/drivers/watchdog/rzg2l_wdt.c
@@ -43,6 +43,8 @@  struct rzg2l_wdt_priv {
 	struct reset_control *rstc;
 	unsigned long osc_clk_rate;
 	unsigned long delay;
+	struct clk *pclk;
+	struct clk *osc_clk;
 };
 
 static void rzg2l_wdt_wait_delay(struct rzg2l_wdt_priv *priv)
@@ -118,7 +120,9 @@  static int rzg2l_wdt_restart(struct watchdog_device *wdev,
 
 	/* Reset the module before we modify any register */
 	reset_control_reset(priv->rstc);
-	pm_runtime_get_sync(wdev->parent);
+
+	clk_prepare_enable(priv->pclk);
+	clk_prepare_enable(priv->osc_clk);
 
 	/* smallest counter value to reboot soon */
 	rzg2l_wdt_write(priv, WDTSET_COUNTER_VAL(1), WDTSET);
@@ -165,7 +169,6 @@  static int rzg2l_wdt_probe(struct platform_device *pdev)
 	struct device *dev = &pdev->dev;
 	struct rzg2l_wdt_priv *priv;
 	unsigned long pclk_rate;
-	struct clk *wdt_clk;
 	int ret;
 
 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
@@ -177,22 +180,20 @@  static int rzg2l_wdt_probe(struct platform_device *pdev)
 		return PTR_ERR(priv->base);
 
 	/* Get watchdog main clock */
-	wdt_clk = clk_get(&pdev->dev, "oscclk");
-	if (IS_ERR(wdt_clk))
-		return dev_err_probe(&pdev->dev, PTR_ERR(wdt_clk), "no oscclk");
+	priv->osc_clk = devm_clk_get(&pdev->dev, "oscclk");
+	if (IS_ERR(priv->osc_clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(priv->osc_clk), "no oscclk");
 
-	priv->osc_clk_rate = clk_get_rate(wdt_clk);
-	clk_put(wdt_clk);
+	priv->osc_clk_rate = clk_get_rate(priv->osc_clk);
 	if (!priv->osc_clk_rate)
 		return dev_err_probe(&pdev->dev, -EINVAL, "oscclk rate is 0");
 
 	/* Get Peripheral clock */
-	wdt_clk = clk_get(&pdev->dev, "pclk");
-	if (IS_ERR(wdt_clk))
-		return dev_err_probe(&pdev->dev, PTR_ERR(wdt_clk), "no pclk");
+	priv->pclk = devm_clk_get(&pdev->dev, "pclk");
+	if (IS_ERR(priv->pclk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(priv->pclk), "no pclk");
 
-	pclk_rate = clk_get_rate(wdt_clk);
-	clk_put(wdt_clk);
+	pclk_rate = clk_get_rate(priv->pclk);
 	if (!pclk_rate)
 		return dev_err_probe(&pdev->dev, -EINVAL, "pclk rate is 0");