linux-kernel - Re: [PATCH 09/14] bus: ti-sysc: Move rstctrl reset to happen later

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Message-ID: <20190326231306.GC49658@atomide.com>
Date:   Tue, 26 Mar 2019 16:13:06 -0700
From:   Tony Lindgren <tony@...mide.com>
To:     linux-omap@...r.kernel.org
Cc:     Dave Gerlach <d-gerlach@...com>, Faiz Abbas <faiz_abbas@...com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Keerthy <j-keerthy@...com>, Nishanth Menon <nm@...com>,
        Peter Ujfalusi <peter.ujfalusi@...com>,
        Roger Quadros <rogerq@...com>, Suman Anna <s-anna@...com>,
        Tero Kristo <t-kristo@...com>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 09/14] bus: ti-sysc: Move rstctrl reset to happen later

* Tony Lindgren <tony@...mide.com> [190325 22:00]:
> We should not do the reset until the clocks are enabled. Let's only init
> restctrl in sysc_init_resets() and do the reset later on in sysc_reset().
...

>  static int sysc_reset(struct sysc *ddata)
>  {
>  	int offset = ddata->offsets[SYSC_SYSCONFIG];
> -	int val;
> +	int error, val;
>  
>  	if (ddata->legacy_mode || offset < 0 ||
>  	    ddata->cfg.quirks & SYSC_QUIRK_NO_RESET_ON_INIT)
> -		return 0;
> +		return sysc_rstctrl_reset_deassert(ddata, false);
> +
> +	error = sysc_rstctrl_reset_deassert(ddata, true);
> +	if (error)
> +		return error;

This change is wrong, we need to deassert rstctrl reset before
we enable clocks, not after. Updated version below.

Regards,

Tony

8< --------------------
>From tony Mon Sep 17 00:00:00 2001
From: Tony Lindgren <tony@...mide.com>
Date: Thu, 21 Mar 2019 11:00:21 -0700
Subject: [PATCH] bus: ti-sysc: Move rstctrl reset to happen later

We can do the rsstctrl a bit later, but need to deassert rstctrl reset
before the clocks are enabled if asserted. Let's only init restctrl
in sysc_init_resets() and do the reset later on just before we enable
the device clocks.

Signed-off-by: Tony Lindgren <tony@...mide.com>
---
 drivers/bus/ti-sysc.c | 61 +++++++++++++++++++++++++++----------------
 1 file changed, 39 insertions(+), 22 deletions(-)

diff --git a/drivers/bus/ti-sysc.c b/drivers/bus/ti-sysc.c
--- a/drivers/bus/ti-sysc.c
+++ b/drivers/bus/ti-sysc.c
@@ -339,38 +339,18 @@ static void sysc_disable_opt_clocks(struct sysc *ddata)
 }
 
 /**
- * sysc_init_resets - reset module on init
+ * sysc_init_resets - init rstctrl reset line if configured
  * @ddata: device driver data
  *
- * A module can have both OCP softreset control and external rstctrl.
- * If more complicated rstctrl resets are needed, please handle these
- * directly from the child device driver and map only the module reset
- * for the parent interconnect target module device.
- *
- * Automatic reset of the module on init can be skipped with the
- * "ti,no-reset-on-init" device tree property.
+ * See sysc_rstctrl_reset_deassert().
  */
 static int sysc_init_resets(struct sysc *ddata)
 {
-	int error;
-
 	ddata->rsts =
 		devm_reset_control_array_get_optional_exclusive(ddata->dev);
 	if (IS_ERR(ddata->rsts))
 		return PTR_ERR(ddata->rsts);
 
-	if (ddata->cfg.quirks & SYSC_QUIRK_NO_RESET_ON_INIT)
-		goto deassert;
-
-	error = reset_control_assert(ddata->rsts);
-	if (error)
-		return error;
-
-deassert:
-	error = reset_control_deassert(ddata->rsts);
-	if (error)
-		return error;
-
 	return 0;
 }
 
@@ -1031,6 +1011,35 @@ static int sysc_legacy_init(struct sysc *ddata)
 	return error;
 }
 
+/**
+ * sysc_rstctrl_reset_deassert - deassert rstctrl reset
+ * @ddata: device driver data
+ * @reset: reset before deassert
+ *
+ * A module can have both OCP softreset control and external rstctrl.
+ * If more complicated rstctrl resets are needed, please handle these
+ * directly from the child device driver and map only the module reset
+ * for the parent interconnect target module device.
+ *
+ * Automatic reset of the module on init can be skipped with the
+ * "ti,no-reset-on-init" device tree property.
+ */
+static int sysc_rstctrl_reset_deassert(struct sysc *ddata, bool reset)
+{
+	int error;
+
+	if (!ddata->rsts)
+		return 0;
+
+	if (reset) {
+		error = reset_control_assert(ddata->rsts);
+		if (error)
+			return error;
+	}
+
+	return reset_control_deassert(ddata->rsts);
+}
+
 static int sysc_reset(struct sysc *ddata)
 {
 	int offset = ddata->offsets[SYSC_SYSCONFIG];
@@ -1071,6 +1080,14 @@ static int sysc_init_module(struct sysc *ddata)
 {
 	int error = 0;
 	bool manage_clocks = true;
+	bool reset = true;
+
+	if (ddata->cfg.quirks & SYSC_QUIRK_NO_RESET_ON_INIT)
+		reset = false;
+
+	error = sysc_rstctrl_reset_deassert(ddata, reset);
+	if (error)
+		return error;
 
 	if (ddata->cfg.quirks &
 	    (SYSC_QUIRK_NO_IDLE | SYSC_QUIRK_NO_IDLE_ON_INIT))
-- 
2.21.0