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Subject[PATCH v3 3/3] counter: 104-quad-8: Add lock guards for filter clock prescaler
Add lock protection from race conditions in the 104-quad-8 counter
driver for filter clock prescaler related changes. There is no IRQ
handling so used spin_lock calls for protection.

Fixes: 9b74dddf79be ("counter: 104-quad-8: Support Filter Clock
Prescaler")

Signed-off-by: Syed Nayyar Waris <syednwaris@gmail.com>

Split the patch from generic interface and differential encoder cable
status changes. Also, include more code statements for protection using
spin_lock calls and remove protection from few code statements which are
unnecessary.
---
drivers/counter/104-quad-8.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c
index 9dab190..58615e4 100644
--- a/drivers/counter/104-quad-8.c
+++ b/drivers/counter/104-quad-8.c
@@ -1230,6 +1230,8 @@ static ssize_t quad8_signal_fck_prescaler_write(struct counter_device *counter,
if (ret)
return ret;

+ spin_lock(&priv->lock);
+
priv->fck_prescaler[channel_id] = prescaler;

/* Reset Byte Pointer */
@@ -1240,6 +1242,8 @@ static ssize_t quad8_signal_fck_prescaler_write(struct counter_device *counter,
outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP | QUAD8_RLD_PRESET_PSC,
base_offset + 1);

+ spin_unlock(&priv->lock);
+
return len;
}

--
2.7.4
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