diff options
author | Ian Abbott <abbotti@mev.co.uk> | 2018-10-31 12:29:56 +0000 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-11-07 13:05:39 +0100 |
commit | 48164754d7fe219911b7653449a4ce85d23c3556 (patch) | |
tree | bb0d7c2aff7011efca1cf02a116687da2de1d822 | |
parent | e3b9ea9aae7e1576516da2b125d7add20663f591 (diff) |
staging: comedi: addi_apci_3501: Use insn->n in EEPROM insn_read handler
The `insn_read` handler for the EEPROM subdevice
(`apci3501_eeprom_insn_read()`) currently ignores `insn->n` (the number
of samples to be read) and assumes a single sample is to be read. But
`insn->n` could be 0, meaning no samples should be read, in which case
`data[0]` ought not to be written. (The comedi core at least ensures
that `data[0]` exists, but we should not rely on that.)
Following the usual Comedi guidelines and interpret `insn->n` as the
number of samples to be read, but only read the EEPROM location once and
make `insn->n` copies, as we don't expect the contents of the EEPROM
location to change between readings.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | drivers/staging/comedi/drivers/addi_apci_3501.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/drivers/staging/comedi/drivers/addi_apci_3501.c b/drivers/staging/comedi/drivers/addi_apci_3501.c index a38267928e5e..b4aa588975df 100644 --- a/drivers/staging/comedi/drivers/addi_apci_3501.c +++ b/drivers/staging/comedi/drivers/addi_apci_3501.c @@ -258,8 +258,15 @@ static int apci3501_eeprom_insn_read(struct comedi_device *dev, { struct apci3501_private *devpriv = dev->private; unsigned short addr = CR_CHAN(insn->chanspec); + unsigned int val; + unsigned int i; - data[0] = apci3501_eeprom_readw(devpriv->amcc, 2 * addr); + if (insn->n) { + /* No point reading the same EEPROM location more than once. */ + val = apci3501_eeprom_readw(devpriv->amcc, 2 * addr); + for (i = 0; i < insn->n; i++) + data[i] = val; + } return insn->n; } |