[3.11.y.z extended stable] Patch "ARM: OMAP2+: hwmod: Fix SOFTRESET logic" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    ARM: OMAP2+: hwmod: Fix SOFTRESET logic

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 3d3df26b6e61725bb351ee88b6a086dd2d2b0b49 Mon Sep 17 00:00:00 2001
From: Roger Quadros <rogerq at ti.com>
Date: Sun, 8 Dec 2013 18:39:02 -0700
Subject: ARM: OMAP2+: hwmod: Fix SOFTRESET logic

commit 313a76ee11cda6700548afe68499ef174a240688 upstream.

In _ocp_softreset(), after _set_softreset() + write_sysconfig(),
the hwmod's sysc_cache will always contain SOFTRESET bit set
so all further writes to sysconfig using this cache will initiate
a repeated SOFTRESET e.g. enable_sysc(). This is true for OMAP3 like
platforms that have RESET_DONE status in the SYSSTATUS register and
so the the SOFTRESET bit in SYSCONFIG is not automatically cleared.
It is not a problem for OMAP4 like platforms that indicate RESET
completion by clearing the SOFTRESET bit in the SYSCONFIG register.

This repeated SOFTRESET is undesired and was the root cause of
USB host issues on OMAP3 platforms when hwmod was allowed to do the
SOFTRESET for the USB Host module.

To fix this we clear the SOFTRESET bit and update the sysconfig
register + sysc_cache using write_sysconfig().

Signed-off-by: Roger Quadros <rogerq at ti.com>
Tested-by: Tomi Valkeinen <tomi.valkeinen at ti.com> # Panda, BeagleXM
[paul at pwsan.com: renamed _clr_softreset() to _clear_softreset()]
Signed-off-by: Paul Walmsley <paul at pwsan.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 arch/arm/mach-omap2/omap_hwmod.c | 43 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 42 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c
index 7f4db12..b3a8106 100644
--- a/arch/arm/mach-omap2/omap_hwmod.c
+++ b/arch/arm/mach-omap2/omap_hwmod.c
@@ -399,7 +399,7 @@ static int _set_clockactivity(struct omap_hwmod *oh, u8 clockact, u32 *v)
 }

 /**
- * _set_softreset: set OCP_SYSCONFIG.CLOCKACTIVITY bits in @v
+ * _set_softreset: set OCP_SYSCONFIG.SOFTRESET bit in @v
  * @oh: struct omap_hwmod *
  * @v: pointer to register contents to modify
  *
@@ -427,6 +427,36 @@ static int _set_softreset(struct omap_hwmod *oh, u32 *v)
 }

 /**
+ * _clear_softreset: clear OCP_SYSCONFIG.SOFTRESET bit in @v
+ * @oh: struct omap_hwmod *
+ * @v: pointer to register contents to modify
+ *
+ * Clear the SOFTRESET bit in @v for hwmod @oh.  Returns -EINVAL upon
+ * error or 0 upon success.
+ */
+static int _clear_softreset(struct omap_hwmod *oh, u32 *v)
+{
+	u32 softrst_mask;
+
+	if (!oh->class->sysc ||
+	    !(oh->class->sysc->sysc_flags & SYSC_HAS_SOFTRESET))
+		return -EINVAL;
+
+	if (!oh->class->sysc->sysc_fields) {
+		WARN(1,
+		     "omap_hwmod: %s: sysc_fields absent for sysconfig class\n",
+		     oh->name);
+		return -EINVAL;
+	}
+
+	softrst_mask = (0x1 << oh->class->sysc->sysc_fields->srst_shift);
+
+	*v &= ~softrst_mask;
+
+	return 0;
+}
+
+/**
  * _wait_softreset_complete - wait for an OCP softreset to complete
  * @oh: struct omap_hwmod * to wait on
  *
@@ -1909,6 +1939,12 @@ static int _ocp_softreset(struct omap_hwmod *oh)
 	ret = _set_softreset(oh, &v);
 	if (ret)
 		goto dis_opt_clks;
+
+	_write_sysconfig(v, oh);
+	ret = _clear_softreset(oh, &v);
+	if (ret)
+		goto dis_opt_clks;
+
 	_write_sysconfig(v, oh);

 	if (oh->class->sysc->srst_udelay)
@@ -3148,6 +3184,11 @@ int omap_hwmod_softreset(struct omap_hwmod *oh)
 		goto error;
 	_write_sysconfig(v, oh);

+	ret = _clear_softreset(oh, &v);
+	if (ret)
+		goto error;
+	_write_sysconfig(v, oh);
+
 error:
 	return ret;
 }
--
1.8.3.2