My coworkers and I were setting some enclosure states on our storage devices, and then reading the states back using sysfs, and came across the 'fault' field being set to 2. When we investigated into the ses.c file, we found this wonderful comment:
/* For device slot and array device slot elements, byte 3 bit 6
* is "fault sensed" while byte 3 bit 5 is "fault reqstd". As this
* code stands these bits are shifted 4 positions right so in
* sysfs they will appear as bits 2 and 1 respectively. Strange. */
static void ses_get_fault(struct enclosure_device *edev,
struct enclosure_component *ecomp)
{
unsigned char *desc;
desc = ses_get_page2_descriptor(edev, ecomp);
if (desc)
ecomp->fault = (desc[3] & 0x60) >> 4;
}
I was hoping there might be an explanation (purely for curiosity's sake) why it was not shifted 5 positions? Or why it wasn't exported as 2 fields in sysfs, each representing 1 bit in the SES page?
Thanks,
Ryan Attard
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