lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Mon, 9 Dec 2013 01:32:54 +0000 (UTC)
From:	Paul Walmsley <paul@...an.com>
To:	Roger Quadros <rogerq@...com>
cc:	bcousson@...libre.com, tony@...mide.com, tomi.valkeinen@...com,
	balbi@...com, sr@...x.de, David.Laight@...LAB.COM,
	michael@...rulasolutions.com, bigeasy@...utronix.de,
	linux-omap@...r.kernel.org, linux-usb@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] ARM: OMAP2+: hwmod: Fix RESET logic

Hi Roger,

On Tue, 3 Dec 2013, Roger Quadros wrote:

> 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.

Doh :-(

Nice catch.  Renamed _clr_softreset() to _clear_softreset() and queued 
the following for v3.13-rc.


- Paul


From: Roger Quadros <rogerq@...com>

ARM: OMAP2+: hwmod: Fix SOFTRESET logic

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@...com>
[paul@...an.com: renamed _clr_softreset() to _clear_softreset()]
Signed-off-by: Paul Walmsley <paul@...an.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 e3f0ecaf87dd..cacc0c7e8634 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
  *
@@ -1911,6 +1941,12 @@ 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)
@@ -3169,6 +3205,11 @@ 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;
 }
-- 
1.8.4.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ