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w1: mxc_w1: Fix timeout resolution problem leading to bus error

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commit c9723750a6 upstream.

On my platform (i.MX53) bus access sometimes fails with
	w1_search: max_slave_count 64 reached, will continue next search.

The reason is the use of jiffies to implement a 200us timeout in
mxc_w1_ds2_touch_bit().
On some platforms the jiffies timer resolution is insufficient for this.

Fix by replacing jiffies by ktime_get().

For consistency apply the same change to the other use of jiffies in
mxc_w1_ds2_reset_bus().

Fixes: f80b2581a7 ("w1: mxc_w1: Optimize mxc_w1_ds2_touch_bit()")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Martin Fuzzey <martin.fuzzey@flowbird.group>
Link: https://lore.kernel.org/r/1601455030-6607-1-git-send-email-martin.fuzzey@flowbird.group
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Martin Fuzzey 2020-09-30 10:36:46 +02:00 committed by Greg Kroah-Hartman
parent a034ea12bd
commit 3fc2cbba40
1 changed files with 7 additions and 7 deletions
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14
drivers/w1/masters/mxc_w1.c
View file

@ -7,7 +7,7 @@
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/jiffies.h>
#include <linux/ktime.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/platform_device.h>
@ -40,12 +40,12 @@ struct mxc_w1_device {
static u8 mxc_w1_ds2_reset_bus(void *data)
{
struct mxc_w1_device *dev = data;
unsigned long timeout;
ktime_t timeout;
writeb(MXC_W1_CONTROL_RPP, dev->regs + MXC_W1_CONTROL);
/* Wait for reset sequence 511+512us, use 1500us for sure */
timeout = jiffies + usecs_to_jiffies(1500);
timeout = ktime_add_us(ktime_get(), 1500);
udelay(511 + 512);
@ -55,7 +55,7 @@ static u8 mxc_w1_ds2_reset_bus(void *data)
/* PST bit is valid after the RPP bit is self-cleared */
if (!(ctrl & MXC_W1_CONTROL_RPP))
return !(ctrl & MXC_W1_CONTROL_PST);
} while (time_is_after_jiffies(timeout));
} while (ktime_before(ktime_get(), timeout));
return 1;
}
@ -68,12 +68,12 @@ static u8 mxc_w1_ds2_reset_bus(void *data)
static u8 mxc_w1_ds2_touch_bit(void *data, u8 bit)
{
struct mxc_w1_device *dev = data;
unsigned long timeout;
ktime_t timeout;
writeb(MXC_W1_CONTROL_WR(bit), dev->regs + MXC_W1_CONTROL);
/* Wait for read/write bit (60us, Max 120us), use 200us for sure */
timeout = jiffies + usecs_to_jiffies(200);
timeout = ktime_add_us(ktime_get(), 200);
udelay(60);
@ -83,7 +83,7 @@ static u8 mxc_w1_ds2_touch_bit(void *data, u8 bit)
/* RDST bit is valid after the WR1/RD bit is self-cleared */
if (!(ctrl & MXC_W1_CONTROL_WR(bit)))
return !!(ctrl & MXC_W1_CONTROL_RDST);
} while (time_is_after_jiffies(timeout));
} while (ktime_before(ktime_get(), timeout));
return 0;
}