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| author | Jean-Francois Dagenais <jeff.dagenais@gmail.com> | 2013-03-15 14:20:25 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-03-15 12:15:02 -0700 |
| commit | aceca2854498de7384ee7b44d8eb7820fd4c7f16 (patch) | |
| tree | e48272e0dbb1e32ba947fbf9e6df6adea8860a26 /drivers/w1 | |
| parent | 96dd86fa588169b745a71aedf2070e80f4943623 (diff) | |
| download | blackbird-obmc-linux-aceca2854498de7384ee7b44d8eb7820fd4c7f16.tar.gz blackbird-obmc-linux-aceca2854498de7384ee7b44d8eb7820fd4c7f16.zip | |
w1: ds2408: make value read-back check a Kconfig option
De-activating this reading back will effectively half the time required
for a write to the output register.
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Jean-Francois Dagenais <jeff.dagenais@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/w1')
| -rw-r--r-- | drivers/w1/slaves/Kconfig | 10 | ||||
| -rw-r--r-- | drivers/w1/slaves/w1_ds2408.c | 18 |
2 files changed, 22 insertions, 6 deletions
diff --git a/drivers/w1/slaves/Kconfig b/drivers/w1/slaves/Kconfig index 762561fbabbf..5e6a3c9e510b 100644 --- a/drivers/w1/slaves/Kconfig +++ b/drivers/w1/slaves/Kconfig @@ -22,6 +22,16 @@ config W1_SLAVE_DS2408 Say Y here if you want to use a 1-wire DS2408 8-Channel Addressable Switch device support +config W1_SLAVE_DS2408_READBACK + bool "Read-back values written to DS2408's output register" + depends on W1_SLAVE_DS2408 + default y + help + Enabling this will cause the driver to read back the values written + to the chip's output register in order to detect errors. + + This is slower but useful when debugging chips and/or busses. + config W1_SLAVE_DS2413 tristate "Dual Channel Addressable Switch 0x3a family support (DS2413)" help diff --git a/drivers/w1/slaves/w1_ds2408.c b/drivers/w1/slaves/w1_ds2408.c index 441ad3a3b586..25a5168ab522 100644 --- a/drivers/w1/slaves/w1_ds2408.c +++ b/drivers/w1/slaves/w1_ds2408.c @@ -178,6 +178,15 @@ static ssize_t w1_f29_write_output( w1_write_block(sl->master, w1_buf, 3); readBack = w1_read_8(sl->master); + + if (readBack != W1_F29_SUCCESS_CONFIRM_BYTE) { + if (w1_reset_resume_command(sl->master)) + goto error; + /* try again, the slave is ready for a command */ + continue; + } + +#ifdef CONFIG_W1_SLAVE_DS2408_READBACK /* here the master could read another byte which would be the PIO reg (the actual pin logic state) since in this driver we don't know which pins are @@ -186,11 +195,6 @@ static ssize_t w1_f29_write_output( if (w1_reset_resume_command(sl->master)) goto error; - if (readBack != 0xAA) { - /* try again, the slave is ready for a command */ - continue; - } - /* go read back the output latches */ /* (the direct effect of the write above) */ w1_buf[0] = W1_F29_FUNC_READ_PIO_REGS; @@ -198,7 +202,9 @@ static ssize_t w1_f29_write_output( w1_buf[2] = 0; w1_write_block(sl->master, w1_buf, 3); /* read the result of the READ_PIO_REGS command */ - if (w1_read_8(sl->master) == *buf) { + if (w1_read_8(sl->master) == *buf) +#endif + { /* success! */ mutex_unlock(&sl->master->bus_mutex); dev_dbg(&sl->dev, |
