[PATCH v2 0/2] omap i2c interrupt handler fixes

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* [PATCH v2 0/2] omap i2c interrupt handler fixes
@ 2009-12-21 11:29 Alexander Shishkin
  2009-12-21 11:29 ` [PATCH v2 1/2] omap i2c: make errata 1.153 workaround a separate function Alexander Shishkin
  0 siblings, 1 reply; 9+ messages in thread
From: Alexander Shishkin @ 2009-12-21 11:29 UTC (permalink / raw)
  To: ben-linux; +Cc: nm, linux-omap, linux-i2c

Hi,

This is the second version of the patchset, now addressing comments
from Nishanth and changing the retry counter into a real timeout.

Regards,
--
Alex

^ permalink raw reply	[flat|nested] 9+ messages in thread

* [PATCH v2 1/2] omap i2c: make errata 1.153 workaround a separate function
  2009-12-21 11:29 [PATCH v2 0/2] omap i2c interrupt handler fixes Alexander Shishkin
@ 2009-12-21 11:29 ` Alexander Shishkin
  2009-12-21 11:29   ` [PATCH v2 2/2] omap i2c: add a timeout to the busy waiting Alexander Shishkin
       [not found]   ` <1261394999-20857-2-git-send-email-virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org>
  0 siblings, 2 replies; 9+ messages in thread
From: Alexander Shishkin @ 2009-12-21 11:29 UTC (permalink / raw)
  To: ben-linux; +Cc: nm, linux-omap, linux-i2c, Alexander Shishkin

This is to avoid insanely long lines and levels of indentation.

Signed-off-by: Alexander Shishkin <virtuoso@slind.org>
CC: linux-i2c@vger.kernel.org
CC: linux-omap@vger.kernel.org
CC: nm@ti.com
---
 drivers/i2c/busses/i2c-omap.c |   43 ++++++++++++++++++++++------------------
 1 files changed, 24 insertions(+), 19 deletions(-)

diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index 75bf3ad..2d146ac 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -671,6 +671,27 @@ omap_i2c_rev1_isr(int this_irq, void *dev_id)
 #define omap_i2c_rev1_isr		NULL
 #endif
 
+/*
+ * OMAP3430 Errata 1.153: When an XRDY/XDR is hit, wait for XUDF before writing
+ * data to DATA_REG. Otherwise some data bytes can be lost while transferring
+ * them from the memory to the I2C interface.
+ */
+static int errata_omap3_1p153(struct omap_i2c_dev *dev, u16 *stat, int *err)
+{
+	while (!(*stat & OMAP_I2C_STAT_XUDF)) {
+		if (*stat & (OMAP_I2C_STAT_NACK | OMAP_I2C_STAT_AL)) {
+			omap_i2c_ack_stat(dev, *stat & (OMAP_I2C_STAT_XRDY |
+							OMAP_I2C_STAT_XDR));
+			*err |= OMAP_I2C_STAT_XUDF;
+			return -ETIMEDOUT;
+		}
+		cpu_relax();
+		*stat = omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG);
+	}
+
+	return 0;
+}
+
 static irqreturn_t
 omap_i2c_isr(int this_irq, void *dev_id)
 {
@@ -794,25 +815,9 @@ complete:
 					break;
 				}
 
-				/*
-				 * OMAP3430 Errata 1.153: When an XRDY/XDR
-				 * is hit, wait for XUDF before writing data
-				 * to DATA_REG. Otherwise some data bytes can
-				 * be lost while transferring them from the
-				 * memory to the I2C interface.
-				 */
-
-				if (dev->rev <= OMAP_I2C_REV_ON_3430) {
-						while (!(stat & OMAP_I2C_STAT_XUDF)) {
-							if (stat & (OMAP_I2C_STAT_NACK | OMAP_I2C_STAT_AL)) {
-								omap_i2c_ack_stat(dev, stat & (OMAP_I2C_STAT_XRDY | OMAP_I2C_STAT_XDR));
-								err |= OMAP_I2C_STAT_XUDF;
-								goto complete;
-							}
-							cpu_relax();
-							stat = omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG);
-						}
-				}
+				if ((dev->rev <= OMAP_I2C_REV_ON_3430) &&
+				    errata_omap3_1p153(dev, &stat, &err))
+					goto complete;
 
 				omap_i2c_write_reg(dev, OMAP_I2C_DATA_REG, w);
 			}
-- 
1.6.3.3


^ permalink raw reply related	[flat|nested] 9+ messages in thread

* [PATCH v2 2/2] omap i2c: add a timeout to the busy waiting
  2009-12-21 11:29 ` [PATCH v2 1/2] omap i2c: make errata 1.153 workaround a separate function Alexander Shishkin
@ 2009-12-21 11:29   ` Alexander Shishkin
  2009-12-29  0:15     ` Tony Lindgren
       [not found]   ` <1261394999-20857-2-git-send-email-virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org>
  1 sibling, 1 reply; 9+ messages in thread
From: Alexander Shishkin @ 2009-12-21 11:29 UTC (permalink / raw)
  To: ben-linux; +Cc: nm, linux-omap, linux-i2c, Alexander Shishkin

The errata 1.153 workaround is busy waiting on XUDF bit in interrupt
context, which may lead to kernel hangs. The problem can be reproduced
by running the bus with wrong (too high) speed.

Signed-off-by: Alexander Shishkin <virtuoso@slind.org>
CC: linux-i2c@vger.kernel.org
CC: linux-omap@vger.kernel.org
CC: nm@ti.com
---
 drivers/i2c/busses/i2c-omap.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index 2d146ac..7d56a25 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -678,6 +678,8 @@ omap_i2c_rev1_isr(int this_irq, void *dev_id)
  */
 static int errata_omap3_1p153(struct omap_i2c_dev *dev, u16 *stat, int *err)
 {
+	unsigned long timeout = jiffies + msecs_to_jiffies(1);
+
 	while (!(*stat & OMAP_I2C_STAT_XUDF)) {
 		if (*stat & (OMAP_I2C_STAT_NACK | OMAP_I2C_STAT_AL)) {
 			omap_i2c_ack_stat(dev, *stat & (OMAP_I2C_STAT_XRDY |
@@ -685,6 +687,12 @@ static int errata_omap3_1p153(struct omap_i2c_dev *dev, u16 *stat, int *err)
 			*err |= OMAP_I2C_STAT_XUDF;
 			return -ETIMEDOUT;
 		}
+
+		if (time_after(jiffies, timeout)) {
+			dev_err(dev->dev, "timeout waiting on XUDF bit\n");
+			return 0;
+		}
+
 		cpu_relax();
 		*stat = omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG);
 	}
-- 
1.6.3.3


^ permalink raw reply related	[flat|nested] 9+ messages in thread

* Re: [PATCH v2 2/2] omap i2c: add a timeout to the busy waiting
  2009-12-21 11:29   ` [PATCH v2 2/2] omap i2c: add a timeout to the busy waiting Alexander Shishkin
@ 2009-12-29  0:15     ` Tony Lindgren
  0 siblings, 0 replies; 9+ messages in thread
From: Tony Lindgren @ 2009-12-29  0:15 UTC (permalink / raw)
  To: Alexander Shishkin; +Cc: ben-linux, nm, linux-omap, linux-i2c

* Alexander Shishkin <virtuoso@slind.org> [091221 03:30]:
> The errata 1.153 workaround is busy waiting on XUDF bit in interrupt
> context, which may lead to kernel hangs. The problem can be reproduced
> by running the bus with wrong (too high) speed.
> 
> Signed-off-by: Alexander Shishkin <virtuoso@slind.org>
> CC: linux-i2c@vger.kernel.org
> CC: linux-omap@vger.kernel.org
> CC: nm@ti.com

Acked-by: Tony Lindgren <tony@atomide.com>

> ---
>  drivers/i2c/busses/i2c-omap.c |    8 ++++++++
>  1 files changed, 8 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
> index 2d146ac..7d56a25 100644
> --- a/drivers/i2c/busses/i2c-omap.c
> +++ b/drivers/i2c/busses/i2c-omap.c
> @@ -678,6 +678,8 @@ omap_i2c_rev1_isr(int this_irq, void *dev_id)
>   */
>  static int errata_omap3_1p153(struct omap_i2c_dev *dev, u16 *stat, int *err)
>  {
> +	unsigned long timeout = jiffies + msecs_to_jiffies(1);
> +
>  	while (!(*stat & OMAP_I2C_STAT_XUDF)) {
>  		if (*stat & (OMAP_I2C_STAT_NACK | OMAP_I2C_STAT_AL)) {
>  			omap_i2c_ack_stat(dev, *stat & (OMAP_I2C_STAT_XRDY |
> @@ -685,6 +687,12 @@ static int errata_omap3_1p153(struct omap_i2c_dev *dev, u16 *stat, int *err)
>  			*err |= OMAP_I2C_STAT_XUDF;
>  			return -ETIMEDOUT;
>  		}
> +
> +		if (time_after(jiffies, timeout)) {
> +			dev_err(dev->dev, "timeout waiting on XUDF bit\n");
> +			return 0;
> +		}
> +
>  		cpu_relax();
>  		*stat = omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG);
>  	}
> -- 
> 1.6.3.3
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

^ permalink raw reply	[flat|nested] 9+ messages in thread

[parent not found: <1261394999-20857-2-git-send-email-virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org>]

* Re: [PATCH v2 1/2] omap i2c: make errata 1.153 workaround a separate function
       [not found]   ` <1261394999-20857-2-git-send-email-virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org>
@ 2009-12-29  0:13     ` Tony Lindgren
  2010-01-05 17:05     ` Alexander Shishkin
  1 sibling, 0 replies; 9+ messages in thread
From: Tony Lindgren @ 2009-12-29  0:13 UTC (permalink / raw)
  To: Alexander Shishkin
  Cc: ben-linux-elnMNo+KYs3YtjvyW6yDsg, nm-l0cyMroinI0,
	linux-omap-u79uwXL29TY76Z2rM5mHXA,
	linux-i2c-u79uwXL29TY76Z2rM5mHXA

* Alexander Shishkin <virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org> [091221 03:29]:
> This is to avoid insanely long lines and levels of indentation.
> 
> Signed-off-by: Alexander Shishkin <virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org>
> CC: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> CC: linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> CC: nm-l0cyMroinI0@public.gmane.org

Nice, this driver sure could use some clean-up.

Acked-by: Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>

> ---
>  drivers/i2c/busses/i2c-omap.c |   43 ++++++++++++++++++++++------------------
>  1 files changed, 24 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
> index 75bf3ad..2d146ac 100644
> --- a/drivers/i2c/busses/i2c-omap.c
> +++ b/drivers/i2c/busses/i2c-omap.c
> @@ -671,6 +671,27 @@ omap_i2c_rev1_isr(int this_irq, void *dev_id)
>  #define omap_i2c_rev1_isr		NULL
>  #endif
>  
> +/*
> + * OMAP3430 Errata 1.153: When an XRDY/XDR is hit, wait for XUDF before writing
> + * data to DATA_REG. Otherwise some data bytes can be lost while transferring
> + * them from the memory to the I2C interface.
> + */
> +static int errata_omap3_1p153(struct omap_i2c_dev *dev, u16 *stat, int *err)
> +{
> +	while (!(*stat & OMAP_I2C_STAT_XUDF)) {
> +		if (*stat & (OMAP_I2C_STAT_NACK | OMAP_I2C_STAT_AL)) {
> +			omap_i2c_ack_stat(dev, *stat & (OMAP_I2C_STAT_XRDY |
> +							OMAP_I2C_STAT_XDR));
> +			*err |= OMAP_I2C_STAT_XUDF;
> +			return -ETIMEDOUT;
> +		}
> +		cpu_relax();
> +		*stat = omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG);
> +	}
> +
> +	return 0;
> +}
> +
>  static irqreturn_t
>  omap_i2c_isr(int this_irq, void *dev_id)
>  {
> @@ -794,25 +815,9 @@ complete:
>  					break;
>  				}
>  
> -				/*
> -				 * OMAP3430 Errata 1.153: When an XRDY/XDR
> -				 * is hit, wait for XUDF before writing data
> -				 * to DATA_REG. Otherwise some data bytes can
> -				 * be lost while transferring them from the
> -				 * memory to the I2C interface.
> -				 */
> -
> -				if (dev->rev <= OMAP_I2C_REV_ON_3430) {
> -						while (!(stat & OMAP_I2C_STAT_XUDF)) {
> -							if (stat & (OMAP_I2C_STAT_NACK | OMAP_I2C_STAT_AL)) {
> -								omap_i2c_ack_stat(dev, stat & (OMAP_I2C_STAT_XRDY | OMAP_I2C_STAT_XDR));
> -								err |= OMAP_I2C_STAT_XUDF;
> -								goto complete;
> -							}
> -							cpu_relax();
> -							stat = omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG);
> -						}
> -				}
> +				if ((dev->rev <= OMAP_I2C_REV_ON_3430) &&
> +				    errata_omap3_1p153(dev, &stat, &err))
> +					goto complete;
>  
>  				omap_i2c_write_reg(dev, OMAP_I2C_DATA_REG, w);
>  			}
> -- 
> 1.6.3.3
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: [PATCH v2 1/2] omap i2c: make errata 1.153 workaround a separate function
       [not found]   ` <1261394999-20857-2-git-send-email-virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org>
  2009-12-29  0:13     ` [PATCH v2 1/2] omap i2c: make errata 1.153 workaround a separate function Tony Lindgren
@ 2010-01-05 17:05     ` Alexander Shishkin
  1 sibling, 0 replies; 9+ messages in thread
From: Alexander Shishkin @ 2010-01-05 17:05 UTC (permalink / raw)
  To: ben-linux-elnMNo+KYs3YtjvyW6yDsg
  Cc: nm-l0cyMroinI0, linux-omap-u79uwXL29TY76Z2rM5mHXA,
	linux-i2c-u79uwXL29TY76Z2rM5mHXA, Alexander Shishkin

On Mon, Dec 21, 2009 at 01:29:58 +0200, Alexander Shishkin wrote:
> This is to avoid insanely long lines and levels of indentation.

Ben, do you want me to resend these with Tony's acks or can you consider
applying them?

Regards,
--
Alex

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: [PATCH 1/2] omap i2c: make errata 1.153 workaround a separate function
@ 2010-03-16 14:30 Tony Lindgren
       [not found] ` <20100316143025.GR2900-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>
  0 siblings, 1 reply; 9+ messages in thread
From: Tony Lindgren @ 2010-03-16 14:30 UTC (permalink / raw)
  To: ben-linux-elnMNo+KYs3YtjvyW6yDsg,
	linux-omap-u79uwXL29TY76Z2rM5mHXA,
	linux-i2c-u79uwXL29TY76Z2rM5mHXA

* Alexander Shishkin <virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org> [100316 04:28]:
> On Wed, Dec 16, 2009 at 04:02:23 +0200, Alexander Shishkin wrote:
> > This is to avoid insanely long lines and levels of indentation.
> 
> These seem to be forgotten. Is there any problem with these I should address?

Can you please repost and I'll add those too into omap-testing
first? Or maybe point to the right patchwork.kernel.org link.

Regards,

Tony

^ permalink raw reply	[flat|nested] 9+ messages in thread

[parent not found: <20100316143025.GR2900-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>]

* [PATCH v2 2/2] omap i2c: add a timeout to the busy waiting
       [not found] ` <20100316143025.GR2900-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>
@ 2010-03-25  9:52   ` Alexander Shishkin
       [not found]     ` <1269510757-8119-3-git-send-email-virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org>
  0 siblings, 1 reply; 9+ messages in thread
From: Alexander Shishkin @ 2010-03-25  9:52 UTC (permalink / raw)
  To: ben-linux-elnMNo+KYs3YtjvyW6yDsg
  Cc: nm-l0cyMroinI0, linux-omap-u79uwXL29TY76Z2rM5mHXA,
	linux-i2c-u79uwXL29TY76Z2rM5mHXA, Tony Lindgren,
	Alexander Shishkin

The errata 1.153 workaround is busy waiting on XUDF bit in interrupt
context, which may lead to kernel hangs. The problem can be reproduced
by running the bus with wrong (too high) speed.

Signed-off-by: Alexander Shishkin <virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org>
Acked-by: Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>
CC: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
CC: linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
CC: nm-l0cyMroinI0@public.gmane.org
---
 drivers/i2c/busses/i2c-omap.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index 2d146ac..7d56a25 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -678,6 +678,8 @@ omap_i2c_rev1_isr(int this_irq, void *dev_id)
  */
 static int errata_omap3_1p153(struct omap_i2c_dev *dev, u16 *stat, int *err)
 {
+	unsigned long timeout = jiffies + msecs_to_jiffies(1);
+
 	while (!(*stat & OMAP_I2C_STAT_XUDF)) {
 		if (*stat & (OMAP_I2C_STAT_NACK | OMAP_I2C_STAT_AL)) {
 			omap_i2c_ack_stat(dev, *stat & (OMAP_I2C_STAT_XRDY |
@@ -685,6 +687,12 @@ static int errata_omap3_1p153(struct omap_i2c_dev *dev, u16 *stat, int *err)
 			*err |= OMAP_I2C_STAT_XUDF;
 			return -ETIMEDOUT;
 		}
+
+		if (time_after(jiffies, timeout)) {
+			dev_err(dev->dev, "timeout waiting on XUDF bit\n");
+			return 0;
+		}
+
 		cpu_relax();
 		*stat = omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG);
 	}
-- 
1.6.3.3

^ permalink raw reply related	[flat|nested] 9+ messages in thread

[parent not found: <1269510757-8119-3-git-send-email-virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org>]

* Re: [PATCH v2 2/2] omap i2c: add a timeout to the busy waiting
       [not found]     ` <1269510757-8119-3-git-send-email-virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org>
@ 2010-03-25 14:38       ` Aaro Koskinen
       [not found]         ` <4BAB7551.6040203-xNZwKgViW5gAvxtiuMwx3w@public.gmane.org>
  0 siblings, 1 reply; 9+ messages in thread
From: Aaro Koskinen @ 2010-03-25 14:38 UTC (permalink / raw)
  To: ext Alexander Shishkin
  Cc: ben-linux-elnMNo+KYs3YtjvyW6yDsg@public.gmane.org,
	nm-l0cyMroinI0@public.gmane.org,
	linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Tony Lindgren

Hi,

Alexander Shishkin wrote:
> The errata 1.153 workaround is busy waiting on XUDF bit in interrupt
> context, which may lead to kernel hangs. The problem can be reproduced
> by running the bus with wrong (too high) speed.
> 
> Signed-off-by: Alexander Shishkin <virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org>
> Acked-by: Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>
> CC: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> CC: linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> CC: nm-l0cyMroinI0@public.gmane.org
> ---
>  drivers/i2c/busses/i2c-omap.c |    8 ++++++++
>  1 files changed, 8 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
> index 2d146ac..7d56a25 100644
> --- a/drivers/i2c/busses/i2c-omap.c
> +++ b/drivers/i2c/busses/i2c-omap.c
> @@ -678,6 +678,8 @@ omap_i2c_rev1_isr(int this_irq, void *dev_id)
>   */
>  static int errata_omap3_1p153(struct omap_i2c_dev *dev, u16 *stat, int *err)
>  {
> +	unsigned long timeout = jiffies + msecs_to_jiffies(1);
> +
>  	while (!(*stat & OMAP_I2C_STAT_XUDF)) {
>  		if (*stat & (OMAP_I2C_STAT_NACK | OMAP_I2C_STAT_AL)) {
>  			omap_i2c_ack_stat(dev, *stat & (OMAP_I2C_STAT_XRDY |
> @@ -685,6 +687,12 @@ static int errata_omap3_1p153(struct omap_i2c_dev *dev, u16 *stat, int *err)
>  			*err |= OMAP_I2C_STAT_XUDF;
>  			return -ETIMEDOUT;
>  		}
> +
> +		if (time_after(jiffies, timeout)) {

This is called from hard interrupt context, so we cannot use jiffies.

> +			dev_err(dev->dev, "timeout waiting on XUDF bit\n");
> +			return 0;
> +		}
> +
>  		cpu_relax();
>  		*stat = omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG);
>  	}

A.

^ permalink raw reply	[flat|nested] 9+ messages in thread

[parent not found: <4BAB7551.6040203-xNZwKgViW5gAvxtiuMwx3w@public.gmane.org>]

* Re: [PATCH v2 2/2] omap i2c: add a timeout to the busy waiting
       [not found]         ` <4BAB7551.6040203-xNZwKgViW5gAvxtiuMwx3w@public.gmane.org>
@ 2010-03-25 15:02           ` Alexander Shishkin
  0 siblings, 0 replies; 9+ messages in thread
From: Alexander Shishkin @ 2010-03-25 15:02 UTC (permalink / raw)
  To: Aaro Koskinen
  Cc: ben-linux-elnMNo+KYs3YtjvyW6yDsg@public.gmane.org,
	nm-l0cyMroinI0@public.gmane.org,
	linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Tony Lindgren

On Thu, Mar 25, 2010 at 04:38:09 +0200, Aaro Koskinen wrote:
> Hi,
> 
> Alexander Shishkin wrote:
> > The errata 1.153 workaround is busy waiting on XUDF bit in interrupt
> > context, which may lead to kernel hangs. The problem can be reproduced
> > by running the bus with wrong (too high) speed.
> > 
> > Signed-off-by: Alexander Shishkin <virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org>
> > Acked-by: Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>
> > CC: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> > CC: linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> > CC: nm-l0cyMroinI0@public.gmane.org
> > ---
> >  drivers/i2c/busses/i2c-omap.c |    8 ++++++++
> >  1 files changed, 8 insertions(+), 0 deletions(-)
> > 
> > diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
> > index 2d146ac..7d56a25 100644
> > --- a/drivers/i2c/busses/i2c-omap.c
> > +++ b/drivers/i2c/busses/i2c-omap.c
> > @@ -678,6 +678,8 @@ omap_i2c_rev1_isr(int this_irq, void *dev_id)
> >   */
> >  static int errata_omap3_1p153(struct omap_i2c_dev *dev, u16 *stat, int *err)
> >  {
> > +	unsigned long timeout = jiffies + msecs_to_jiffies(1);
> > +
> >  	while (!(*stat & OMAP_I2C_STAT_XUDF)) {
> >  		if (*stat & (OMAP_I2C_STAT_NACK | OMAP_I2C_STAT_AL)) {
> >  			omap_i2c_ack_stat(dev, *stat & (OMAP_I2C_STAT_XRDY |
> > @@ -685,6 +687,12 @@ static int errata_omap3_1p153(struct omap_i2c_dev *dev, u16 *stat, int *err)
> >  			*err |= OMAP_I2C_STAT_XUDF;
> >  			return -ETIMEDOUT;
> >  		}
> > +
> > +		if (time_after(jiffies, timeout)) {
> 
> This is called from hard interrupt context, so we cannot use jiffies.

Ahh, stupid me. Then we are left with the iteration counting, I guess.

Regards,
--
Alex

^ permalink raw reply	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2010-03-25 15:02 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2009-12-21 11:29 [PATCH v2 0/2] omap i2c interrupt handler fixes Alexander Shishkin
2009-12-21 11:29 ` [PATCH v2 1/2] omap i2c: make errata 1.153 workaround a separate function Alexander Shishkin
2009-12-21 11:29   ` [PATCH v2 2/2] omap i2c: add a timeout to the busy waiting Alexander Shishkin
2009-12-29  0:15     ` Tony Lindgren
     [not found]   ` <1261394999-20857-2-git-send-email-virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org>
2009-12-29  0:13     ` [PATCH v2 1/2] omap i2c: make errata 1.153 workaround a separate function Tony Lindgren
2010-01-05 17:05     ` Alexander Shishkin
  -- strict thread matches above, loose matches on Subject: below --
2010-03-16 14:30 [PATCH " Tony Lindgren
     [not found] ` <20100316143025.GR2900-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>
2010-03-25  9:52   ` [PATCH v2 2/2] omap i2c: add a timeout to the busy waiting Alexander Shishkin
     [not found]     ` <1269510757-8119-3-git-send-email-virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org>
2010-03-25 14:38       ` Aaro Koskinen
     [not found]         ` <4BAB7551.6040203-xNZwKgViW5gAvxtiuMwx3w@public.gmane.org>
2010-03-25 15:02           ` Alexander Shishkin

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