leandrof/linux
1
0
Fork 0
forked from Minki/linux
Code Issues Pull Requests Packages Projects Releases Wiki Activity

staging: comedi: addi_apci_3501: Use insn->n in EEPROM insn_read handler

Browse Source 
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>
This commit is contained in:
Ian Abbott 2018-10-31 12:29:56 +00:00 committed by Greg Kroah-Hartman
parent e3b9ea9aae
commit 48164754d7
1 changed files with 8 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
drivers/staging/comedi/drivers/addi_apci_3501.c
View File

@ -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;
}