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SubjectRe: [PATCH] w1: ds1wm: add a reset recovery parameter
On Mon, 27 Jun 2011 09:17:58 -0400
Jean-Fran__ois Dagenais <dagenaisj@sonatest.com> wrote:

> This follows the regression on 3.0 reported by Paul Parsons regarding
> the removal of the msleep(1) in the ds1wm_reset() function. This
> sleep should not be required on normal circuitry provided the
> pull-ups on the bus are correctly adapted to the slaves.
> Unfortunately, this is not always the case. The sleep is restored
> but as a parameter to the probe function in the pdata.

A few things.

- When fixing a bug, please fully describe that bug in the changelog.
So that others can determine whether your patch might fix a bug
which they are observing.

That's not so important when we're fixing a regression which was
introduced since the most recent major kernel release, but it's good
practice and who knows, someone might have backported the
regression-introducing patch.

- The patch was missing your signed-off-by. I added it. Please
ack this.

- It's conventional to give bug-reporters a hat tip via the
Reported-by: tag.

Here's what I merged:


From: Jean-Fran_ois Dagenais <dagenaisj@sonatest.com>

This fixes a regression on 3.0 reported by Paul Parsons regarding the
removal of the msleep(1) in the ds1wm_reset() function:

: The linux-3.0-rc4 DS1WM 1-wire driver is logging "bus error, retrying"
: error messages on an HP iPAQ hx4700 PDA (XScale-PXA270):
:
: <snip>
: Driver for 1-wire Dallas network protocol.
: DS1WM w1 busmaster driver - (c) 2004 Szabolcs Gyurko
: 1-Wire driver for the DS2760 battery monitor chip - (c) 2004-2005, Szabolcs Gyurko
: ds1wm ds1wm: pass: 1 bus error, retrying
: ds1wm ds1wm: pass: 2 bus error, retrying
: ds1wm ds1wm: pass: 3 bus error, retrying
: ds1wm ds1wm: pass: 4 bus error, retrying
: ds1wm ds1wm: pass: 5 bus error, retrying
: ...
:
: The visible result is that the battery charging LED is erratic; sometimes
: it works, mostly it doesn't.
:
: The linux-2.6.39 DS1WM 1-wire driver worked OK. I haven't tried 3.0-rc1,
: 3.0-rc2, or 3.0-rc3.

This sleep should not be required on normal circuitry provided the
pull-ups on the bus are correctly adapted to the slaves. Unfortunately,
this is not always the case. The sleep is restored but as a parameter to
the probe function in the pdata.

Reported-by: Paul Parsons <lost.distance@yahoo.com>
Tested-by: Paul Parsons <lost.distance@yahoo.com>
Signed-off-by: Jean-Fran_ois Dagenais <dagenaisj@sonatest.com>
Cc: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

drivers/mfd/asic3.c | 1 +
drivers/mfd/htc-pasic3.c | 1 +
drivers/w1/masters/ds1wm.c | 5 +++++
include/linux/mfd/ds1wm.h | 7 +++++++
4 files changed, 14 insertions(+)

diff -puN drivers/mfd/asic3.c~w1-ds1wm-add-a-reset-recovery-parameter drivers/mfd/asic3.c
--- a/drivers/mfd/asic3.c~w1-ds1wm-add-a-reset-recovery-parameter
+++ a/drivers/mfd/asic3.c
@@ -619,6 +619,7 @@ static void asic3_clk_disable(struct asi
/* MFD cells (SPI, PWM, LED, DS1WM, MMC) */
static struct ds1wm_driver_data ds1wm_pdata = {
.active_high = 1,
+ .reset_recover_delay = 1,
};

static struct resource ds1wm_resources[] = {
diff -puN drivers/mfd/htc-pasic3.c~w1-ds1wm-add-a-reset-recovery-parameter drivers/mfd/htc-pasic3.c
--- a/drivers/mfd/htc-pasic3.c~w1-ds1wm-add-a-reset-recovery-parameter
+++ a/drivers/mfd/htc-pasic3.c
@@ -99,6 +99,7 @@ static int ds1wm_disable(struct platform

static struct ds1wm_driver_data ds1wm_pdata = {
.active_high = 0,
+ .reset_recover_delay = 1,
};

static struct resource ds1wm_resources[] __initdata = {
diff -puN drivers/w1/masters/ds1wm.c~w1-ds1wm-add-a-reset-recovery-parameter drivers/w1/masters/ds1wm.c
--- a/drivers/w1/masters/ds1wm.c~w1-ds1wm-add-a-reset-recovery-parameter
+++ a/drivers/w1/masters/ds1wm.c
@@ -109,6 +109,7 @@ struct ds1wm_data {
/* byte to write that makes all intr disabled, */
/* considering active_state (IAS) (optimization) */
u8 int_en_reg_none;
+ unsigned int reset_recover_delay; /* see ds1wm.h */
};

static inline void ds1wm_write_register(struct ds1wm_data *ds1wm_data, u32 reg,
@@ -187,6 +188,9 @@ static int ds1wm_reset(struct ds1wm_data
return 1;
}

+ if(ds1wm_data->reset_recover_delay)
+ msleep(ds1wm_data->reset_recover_delay);
+
return 0;
}

@@ -490,6 +494,7 @@ static int ds1wm_probe(struct platform_d
}
ds1wm_data->irq = res->start;
ds1wm_data->int_en_reg_none = (plat->active_high ? DS1WM_INTEN_IAS : 0);
+ ds1wm_data->reset_recover_delay = plat->reset_recover_delay;

if (res->flags & IORESOURCE_IRQ_HIGHEDGE)
irq_set_irq_type(ds1wm_data->irq, IRQ_TYPE_EDGE_RISING);
diff -puN include/linux/mfd/ds1wm.h~w1-ds1wm-add-a-reset-recovery-parameter include/linux/mfd/ds1wm.h
--- a/include/linux/mfd/ds1wm.h~w1-ds1wm-add-a-reset-recovery-parameter
+++ a/include/linux/mfd/ds1wm.h
@@ -3,4 +3,11 @@
struct ds1wm_driver_data {
int active_high;
int clock_rate;
+ /* in milliseconds, the amount of time to */
+ /* sleep following a reset pulse. Zero */
+ /* should work if your bus devices recover*/
+ /* time respects the 1-wire spec since the*/
+ /* ds1wm implements the precise timings of*/
+ /* a reset pulse/presence detect sequence.*/
+ unsigned int reset_recover_delay;
};
_



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