* [PATCH] i2c-bfin-twi: handle faulty slave devices better
@ 2010-05-09 11:04 Mike Frysinger
2010-05-09 11:34 ` Ben Dooks
2010-05-10 15:33 ` [PATCH v2] " Mike Frysinger
0 siblings, 2 replies; 6+ messages in thread
From: Mike Frysinger @ 2010-05-09 11:04 UTC (permalink / raw)
To: linux-i2c, Ben Dooks
Cc: linux-kernel, Andrew Morton, uclinux-dist-devel, Michael Hennerich
From: Michael Hennerich <michael.hennerich@analog.com>
Faulty slave devices might drive SDA low after a transfer finishes. So,
when this scenario is detected, have the master generate up to 8 extra
clocks until the SDA is properly released.
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
---
Note: this requires the existing Blackfin TWI patches already sent out
drivers/i2c/busses/i2c-bfin-twi.c | 22 ++++++++++++++++++++++
1 files changed, 22 insertions(+), 0 deletions(-)
diff --git a/drivers/i2c/busses/i2c-bfin-twi.c b/drivers/i2c/busses/i2c-bfin-twi.c
index fb26e5c..f9c05e1 100644
--- a/drivers/i2c/busses/i2c-bfin-twi.c
+++ b/drivers/i2c/busses/i2c-bfin-twi.c
@@ -20,6 +20,7 @@
#include <linux/completion.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
+#include <linux/delay.h>
#include <asm/blackfin.h>
#include <asm/portmux.h>
@@ -159,6 +160,27 @@ static void bfin_twi_handle_interrupt(struct bfin_twi_iface *iface,
if (mast_stat & BUFWRERR)
dev_dbg(&iface->adap.dev, "Buffer Write Error\n");
+ /* Faulty salve devices, may drive SDA low after a transfer
+ * finishes. To release the bus this code generates up to 8
+ * extra clocks until SDA is released.
+ */
+
+ if (read_MASTER_STAT(iface) & SDASEN) {
+ int cnt = 8;
+ do {
+ write_MASTER_CTL(iface, SCLOVR);
+ udelay(6);
+ write_MASTER_CTL(iface, 0);
+ udelay(6);
+ } while ((read_MASTER_STAT(iface) & SDASEN) && cnt--);
+
+ write_MASTER_CTL(iface, SDAOVR | SCLOVR);
+ udelay(6);
+ write_MASTER_CTL(iface, SDAOVR);
+ udelay(6);
+ write_MASTER_CTL(iface, 0);
+ }
+
/* If it is a quick transfer, only address without data,
* not an err, return 1.
*/
--
1.7.1
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] i2c-bfin-twi: handle faulty slave devices better
2010-05-09 11:04 [PATCH] i2c-bfin-twi: handle faulty slave devices better Mike Frysinger
@ 2010-05-09 11:34 ` Ben Dooks
2010-05-09 18:23 ` Mike Frysinger
2010-05-10 15:33 ` [PATCH v2] " Mike Frysinger
1 sibling, 1 reply; 6+ messages in thread
From: Ben Dooks @ 2010-05-09 11:34 UTC (permalink / raw)
To: Mike Frysinger
Cc: linux-i2c, Ben Dooks, linux-kernel, Andrew Morton,
uclinux-dist-devel, Michael Hennerich
On Sun, May 09, 2010 at 07:04:47AM -0400, Mike Frysinger wrote:
> From: Michael Hennerich <michael.hennerich@analog.com>
>
> Faulty slave devices might drive SDA low after a transfer finishes. So,
> when this scenario is detected, have the master generate up to 8 extra
> clocks until the SDA is properly released.
>
> Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
> Signed-off-by: Mike Frysinger <vapier@gentoo.org>
> ---
> Note: this requires the existing Blackfin TWI patches already sent out
hmm, it is late in the -rc series for anything other than critical
bugfixes, will update series tomorrow.
> drivers/i2c/busses/i2c-bfin-twi.c | 22 ++++++++++++++++++++++
> 1 files changed, 22 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-bfin-twi.c b/drivers/i2c/busses/i2c-bfin-twi.c
> index fb26e5c..f9c05e1 100644
> --- a/drivers/i2c/busses/i2c-bfin-twi.c
> +++ b/drivers/i2c/busses/i2c-bfin-twi.c
> @@ -20,6 +20,7 @@
> #include <linux/completion.h>
> #include <linux/interrupt.h>
> #include <linux/platform_device.h>
> +#include <linux/delay.h>
>
> #include <asm/blackfin.h>
> #include <asm/portmux.h>
> @@ -159,6 +160,27 @@ static void bfin_twi_handle_interrupt(struct bfin_twi_iface *iface,
> if (mast_stat & BUFWRERR)
> dev_dbg(&iface->adap.dev, "Buffer Write Error\n");
>
> + /* Faulty salve devices, may drive SDA low after a transfer
spello: slave
> + * finishes. To release the bus this code generates up to 8
> + * extra clocks until SDA is released.
> + */
> +
> + if (read_MASTER_STAT(iface) & SDASEN) {
> + int cnt = 8;
> + do {
> + write_MASTER_CTL(iface, SCLOVR);
> + udelay(6);
> + write_MASTER_CTL(iface, 0);
> + udelay(6);
> + } while ((read_MASTER_STAT(iface) & SDASEN) && cnt--);
> +
> + write_MASTER_CTL(iface, SDAOVR | SCLOVR);
> + udelay(6);
> + write_MASTER_CTL(iface, SDAOVR);
> + udelay(6);
> + write_MASTER_CTL(iface, 0);
> + }
> +
> /* If it is a quick transfer, only address without data,
> * not an err, return 1.
> */
> --
> 1.7.1
>
--
--
Ben
Q: What's a light-year?
A: One-third less calories than a regular year.
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] i2c-bfin-twi: handle faulty slave devices better
2010-05-09 11:34 ` Ben Dooks
@ 2010-05-09 18:23 ` Mike Frysinger
0 siblings, 0 replies; 6+ messages in thread
From: Mike Frysinger @ 2010-05-09 18:23 UTC (permalink / raw)
To: Ben Dooks
Cc: linux-i2c, linux-kernel, Andrew Morton, uclinux-dist-devel,
Michael Hennerich
On Sun, May 9, 2010 at 07:34, Ben Dooks wrote:
> On Sun, May 09, 2010 at 07:04:47AM -0400, Mike Frysinger wrote:
>> From: Michael Hennerich <michael.hennerich@analog.com>
>>
>> Faulty slave devices might drive SDA low after a transfer finishes. So,
>> when this scenario is detected, have the master generate up to 8 extra
>> clocks until the SDA is properly released.
>>
>> Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
>> Signed-off-by: Mike Frysinger <vapier@gentoo.org>
>> ---
>> Note: this requires the existing Blackfin TWI patches already sent out
>
> hmm, it is late in the -rc series for anything other than critical
> bugfixes, will update series tomorrow.
this patch is fine for 2.6.35, but the rest of the series should have
been merged for like 2.6.33 ...
>> drivers/i2c/busses/i2c-bfin-twi.c | 22 ++++++++++++++++++++++
>> 1 files changed, 22 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-bfin-twi.c b/drivers/i2c/busses/i2c-bfin-twi.c
>> index fb26e5c..f9c05e1 100644
>> --- a/drivers/i2c/busses/i2c-bfin-twi.c
>> +++ b/drivers/i2c/busses/i2c-bfin-twi.c
>> @@ -20,6 +20,7 @@
>> #include <linux/completion.h>
>> #include <linux/interrupt.h>
>> #include <linux/platform_device.h>
>> +#include <linux/delay.h>
>>
>> #include <asm/blackfin.h>
>> #include <asm/portmux.h>
>> @@ -159,6 +160,27 @@ static void bfin_twi_handle_interrupt(struct bfin_twi_iface *iface,
>> if (mast_stat & BUFWRERR)
>> dev_dbg(&iface->adap.dev, "Buffer Write Error\n");
>>
>> + /* Faulty salve devices, may drive SDA low after a transfer
> spello: slave
ok, i'll resend in a bit
-mike
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v2] i2c-bfin-twi: handle faulty slave devices better
2010-05-09 11:04 [PATCH] i2c-bfin-twi: handle faulty slave devices better Mike Frysinger
2010-05-09 11:34 ` Ben Dooks
@ 2010-05-10 15:33 ` Mike Frysinger
2010-05-11 23:09 ` Ben Dooks
1 sibling, 1 reply; 6+ messages in thread
From: Mike Frysinger @ 2010-05-10 15:33 UTC (permalink / raw)
To: linux-i2c, Ben Dooks
Cc: uclinux-dist-devel, linux-kernel, Andrew Morton, Michael Hennerich
From: Michael Hennerich <michael.hennerich@analog.com>
Faulty slave devices might drive SDA low after a transfer finishes. So,
when this scenario is detected, have the master generate up to 9 extra
clocks until the SDA is properly released.
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
---
v2
- fix typo in comment pointed out by Ben
- use 9 clocks rather than 8 to cover a possible NACK pointed out by Michael
drivers/i2c/busses/i2c-bfin-twi.c | 22 ++++++++++++++++++++++
1 files changed, 22 insertions(+), 0 deletions(-)
diff --git a/drivers/i2c/busses/i2c-bfin-twi.c b/drivers/i2c/busses/i2c-bfin-twi.c
index fb26e5c..1ee9d5a 100644
--- a/drivers/i2c/busses/i2c-bfin-twi.c
+++ b/drivers/i2c/busses/i2c-bfin-twi.c
@@ -20,6 +20,7 @@
#include <linux/completion.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
+#include <linux/delay.h>
#include <asm/blackfin.h>
#include <asm/portmux.h>
@@ -159,6 +160,27 @@ static void bfin_twi_handle_interrupt(struct bfin_twi_iface *iface,
if (mast_stat & BUFWRERR)
dev_dbg(&iface->adap.dev, "Buffer Write Error\n");
+ /* Faulty slave devices, may drive SDA low after a transfer
+ * finishes. To release the bus this code generates up to 9
+ * extra clocks until SDA is released.
+ */
+
+ if (read_MASTER_STAT(iface) & SDASEN) {
+ int cnt = 9;
+ do {
+ write_MASTER_CTL(iface, SCLOVR);
+ udelay(6);
+ write_MASTER_CTL(iface, 0);
+ udelay(6);
+ } while ((read_MASTER_STAT(iface) & SDASEN) && cnt--);
+
+ write_MASTER_CTL(iface, SDAOVR | SCLOVR);
+ udelay(6);
+ write_MASTER_CTL(iface, SDAOVR);
+ udelay(6);
+ write_MASTER_CTL(iface, 0);
+ }
+
/* If it is a quick transfer, only address without data,
* not an err, return 1.
*/
--
1.7.1
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH v2] i2c-bfin-twi: handle faulty slave devices better
2010-05-10 15:33 ` [PATCH v2] " Mike Frysinger
@ 2010-05-11 23:09 ` Ben Dooks
2010-05-12 0:03 ` Mike Frysinger
0 siblings, 1 reply; 6+ messages in thread
From: Ben Dooks @ 2010-05-11 23:09 UTC (permalink / raw)
To: Mike Frysinger
Cc: linux-i2c, Ben Dooks, uclinux-dist-devel, linux-kernel,
Andrew Morton, Michael Hennerich
On Mon, May 10, 2010 at 11:33:44AM -0400, Mike Frysinger wrote:
> From: Michael Hennerich <michael.hennerich@analog.com>
>
> Faulty slave devices might drive SDA low after a transfer finishes. So,
> when this scenario is detected, have the master generate up to 9 extra
> clocks until the SDA is properly released.
This doesn't apply to my for-2635/i2c-bfin tree, can't find the BUFWERR
patch. will check to see if theres's something i've missed..
> Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
> Signed-off-by: Mike Frysinger <vapier@gentoo.org>
> ---
> v2
> - fix typo in comment pointed out by Ben
> - use 9 clocks rather than 8 to cover a possible NACK pointed out by Michael
>
> drivers/i2c/busses/i2c-bfin-twi.c | 22 ++++++++++++++++++++++
> 1 files changed, 22 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-bfin-twi.c b/drivers/i2c/busses/i2c-bfin-twi.c
> index fb26e5c..1ee9d5a 100644
> --- a/drivers/i2c/busses/i2c-bfin-twi.c
> +++ b/drivers/i2c/busses/i2c-bfin-twi.c
> @@ -20,6 +20,7 @@
> #include <linux/completion.h>
> #include <linux/interrupt.h>
> #include <linux/platform_device.h>
> +#include <linux/delay.h>
>
> #include <asm/blackfin.h>
> #include <asm/portmux.h>
> @@ -159,6 +160,27 @@ static void bfin_twi_handle_interrupt(struct bfin_twi_iface *iface,
> if (mast_stat & BUFWRERR)
> dev_dbg(&iface->adap.dev, "Buffer Write Error\n");
>
> + /* Faulty slave devices, may drive SDA low after a transfer
> + * finishes. To release the bus this code generates up to 9
> + * extra clocks until SDA is released.
> + */
> +
> + if (read_MASTER_STAT(iface) & SDASEN) {
> + int cnt = 9;
> + do {
> + write_MASTER_CTL(iface, SCLOVR);
> + udelay(6);
> + write_MASTER_CTL(iface, 0);
> + udelay(6);
> + } while ((read_MASTER_STAT(iface) & SDASEN) && cnt--);
> +
> + write_MASTER_CTL(iface, SDAOVR | SCLOVR);
> + udelay(6);
> + write_MASTER_CTL(iface, SDAOVR);
> + udelay(6);
> + write_MASTER_CTL(iface, 0);
> + }
> +
> /* If it is a quick transfer, only address without data,
> * not an err, return 1.
> */
> --
> 1.7.1
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
> the body of a message to majordomo@vger.kernel.org
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--
Ben (ben@fluff.org, http://www.fluff.org/)
'a smiley only costs 4 bytes'
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH v2] i2c-bfin-twi: handle faulty slave devices better
2010-05-11 23:09 ` Ben Dooks
@ 2010-05-12 0:03 ` Mike Frysinger
0 siblings, 0 replies; 6+ messages in thread
From: Mike Frysinger @ 2010-05-12 0:03 UTC (permalink / raw)
To: Ben Dooks
Cc: linux-i2c, uclinux-dist-devel, linux-kernel, Andrew Morton,
Michael Hennerich
On Tue, May 11, 2010 at 19:09, Ben Dooks wrote:
> On Mon, May 10, 2010 at 11:33:44AM -0400, Mike Frysinger wrote:
>> From: Michael Hennerich <michael.hennerich@analog.com>
>>
>> Faulty slave devices might drive SDA low after a transfer finishes. So,
>> when this scenario is detected, have the master generate up to 9 extra
>> clocks until the SDA is properly released.
>
> This doesn't apply to my for-2635/i2c-bfin tree, can't find the BUFWERR
> patch. will check to see if theres's something i've missed..
have you applied the other Blackfin I2C patches yet ? the bfin i2c
branch applies cleanly to linus' current tree:
git://git.kernel.org/pub/scm/linux/kernel/git/vapier/blackfin.git for-i2c
-mike
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2010-05-12 0:04 UTC | newest]
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2010-05-09 11:04 [PATCH] i2c-bfin-twi: handle faulty slave devices better Mike Frysinger
2010-05-09 11:34 ` Ben Dooks
2010-05-09 18:23 ` Mike Frysinger
2010-05-10 15:33 ` [PATCH v2] " Mike Frysinger
2010-05-11 23:09 ` Ben Dooks
2010-05-12 0:03 ` Mike Frysinger
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