Re: [PATCH] Input: silead: use msleep() for long delays

From: Hans de Goede
Date: Thu Jan 12 2017 - 12:47:59 EST


Hi,

On 01/12/2017 05:21 PM, Nicholas Mc Guire wrote:
the delays here are in the 10 to 20ms range so msleep() will do - no
need to burden the highres timer subsystem.

Signed-off-by: Nicholas Mc Guire <hofrat@xxxxxxxxx>
---

Problem found by coccinelle script

While msleep(10) has a worst case uncertainty of 10ms (on HZ=100 systems)
this seems ok here as the delays are not called frequently (init and
reset functions)

By the same logic, this is not much of a burden on the high-res timer
subsys though.

and the uncertainty of 10ms fits the permitted range of
the original usleep_ranges().

Either way this patch is fine with me.

Regards,

Hans




Patch was compile tested with: x86_64_defconfig +
CONFIG_TOUCHSCREEN_SILEAD=m

Patch is against 4.10-rc3 (localversion-next is next-20170112)

drivers/input/touchscreen/silead.c | 17 ++++++++---------
1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/drivers/input/touchscreen/silead.c b/drivers/input/touchscreen/silead.c
index 404830a..3aa885c 100644
--- a/drivers/input/touchscreen/silead.c
+++ b/drivers/input/touchscreen/silead.c
@@ -58,8 +58,7 @@
#define SILEAD_POINT_X_MSB_OFF 0x03
#define SILEAD_TOUCH_ID_MASK 0xF0

-#define SILEAD_CMD_SLEEP_MIN 10000
-#define SILEAD_CMD_SLEEP_MAX 20000
+#define SILEAD_CMD_SLEEP_MIN 10 /* 10+ ms */
#define SILEAD_POWER_SLEEP 20
#define SILEAD_STARTUP_SLEEP 30

@@ -190,25 +189,25 @@ static int silead_ts_init(struct i2c_client *client)
SILEAD_CMD_RESET);
if (error)
goto i2c_write_err;
- usleep_range(SILEAD_CMD_SLEEP_MIN, SILEAD_CMD_SLEEP_MAX);
+ msleep(SILEAD_CMD_SLEEP_MIN);

error = i2c_smbus_write_byte_data(client, SILEAD_REG_TOUCH_NR,
data->max_fingers);
if (error)
goto i2c_write_err;
- usleep_range(SILEAD_CMD_SLEEP_MIN, SILEAD_CMD_SLEEP_MAX);
+ msleep(SILEAD_CMD_SLEEP_MIN);

error = i2c_smbus_write_byte_data(client, SILEAD_REG_CLOCK,
SILEAD_CLOCK);
if (error)
goto i2c_write_err;
- usleep_range(SILEAD_CMD_SLEEP_MIN, SILEAD_CMD_SLEEP_MAX);
+ msleep(SILEAD_CMD_SLEEP_MIN);

error = i2c_smbus_write_byte_data(client, SILEAD_REG_RESET,
SILEAD_CMD_START);
if (error)
goto i2c_write_err;
- usleep_range(SILEAD_CMD_SLEEP_MIN, SILEAD_CMD_SLEEP_MAX);
+ msleep(SILEAD_CMD_SLEEP_MIN);

return 0;

@@ -225,19 +224,19 @@ static int silead_ts_reset(struct i2c_client *client)
SILEAD_CMD_RESET);
if (error)
goto i2c_write_err;
- usleep_range(SILEAD_CMD_SLEEP_MIN, SILEAD_CMD_SLEEP_MAX);
+ msleep(SILEAD_CMD_SLEEP_MIN);

error = i2c_smbus_write_byte_data(client, SILEAD_REG_CLOCK,
SILEAD_CLOCK);
if (error)
goto i2c_write_err;
- usleep_range(SILEAD_CMD_SLEEP_MIN, SILEAD_CMD_SLEEP_MAX);
+ msleep(SILEAD_CMD_SLEEP_MIN);

error = i2c_smbus_write_byte_data(client, SILEAD_REG_POWER,
SILEAD_CMD_START);
if (error)
goto i2c_write_err;
- usleep_range(SILEAD_CMD_SLEEP_MIN, SILEAD_CMD_SLEEP_MAX);
+ msleep(SILEAD_CMD_SLEEP_MIN);

return 0;