On 09/11/2018 05:56 PM, Patrick Venture wrote:
Try to get the device ID repeatedly during initialization before giving up.
The BMC isn't always responsive, and this allows it to be slightly flaky
during early boot.
Tested: Installed on a system with the BMC software disabled
such that it was non-responsive. The driver correctly detected this
and gave up as expected. Then I re-enabled the BMC software unloaded
and reloaded the driver and it was detected properly.
The patch looks fine, but I wonder if this is something that is really
valuable.
I have wondered about this before.
The question is: If the BMC is unavailable, what are the chances of it
becoming
available by the time you do 5 attempts? I would guess that is a pretty
small
chance, which is why I haven't done this already.
You could have something that re-tested periodically, but there are so many
systems with IPMI specified in ACPI or SMBIOS that is wrong, and it would
try forever. Also not really a good thing.
So I've left it to reload the driver or use the hotmod interface.
-corey
Signed-off-by: Patrick Venture <vent...@google.com>
---
v2:
- removed extra variable that was set but not used.
---
drivers/char/ipmi/ipmi_si_intf.c | 23 ++++++++++++++++++++++-
1 file changed, 22 insertions(+), 1 deletion(-)
diff --git a/drivers/char/ipmi/ipmi_si_intf.c b/drivers/char/ipmi/ipmi_si_intf.c
index 90ec010bffbd..5fed96897fe8 100644
--- a/drivers/char/ipmi/ipmi_si_intf.c
+++ b/drivers/char/ipmi/ipmi_si_intf.c
@@ -1918,11 +1918,13 @@ int ipmi_si_add_smi(struct si_sm_io *io)
* held, primarily to keep smi_num consistent, we only one to do these
* one at a time.
*/
+#define GET_DEVICE_ID_ATTEMPTS 5
static int try_smi_init(struct smi_info *new_smi)
{
int rv = 0;
int i;
char *init_name = NULL;
+ unsigned long sleep_rm;
pr_info(PFX "Trying %s-specified %s state machine at %s address 0x%lx, slave address 0x%x, irq %d\n",
ipmi_addr_src_to_str(new_smi->io.addr_source),
@@ -2003,7 +2005,26 @@ static int try_smi_init(struct smi_info *new_smi)
* Attempt a get device id command. If it fails, we probably
* don't have a BMC here.
*/
- rv = try_get_dev_id(new_smi);
+ for (i = 0; i < GET_DEVICE_ID_ATTEMPTS; i++) {
+ pr_info(PFX "Attempting to read BMC device ID\n");
+ rv = try_get_dev_id(new_smi);
+ /* If it succeeded, stop trying */
+ if (!rv)
+ break;
+
+ /* Sleep for ~0.25s before trying again instead of hammering
+ * the BMC.
+ */
+ sleep_rm = msleep_interruptible(250);
+ if (sleep_rm != 0) {
+ pr_info(PFX "Find BMC interrupted\n");
+ rv = -EINTR;
+ goto out_err;
+ }
+ }
+
+ /* If we exited the loop above and rv is non-zero we ran out of tries.
+ */
if (rv) {
if (new_smi->io.addr_source)
dev_err(new_smi->io.dev,
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