ichsmb(4) and msleep()

[Yuri Pankov]

Warner Losh wrote:
> On Wed, Aug 28, 2019, 7:01 AM Yuri Pankov <yuripv at yuripv.net> wrote:
> 
>> Yuri Pankov wrote:
>>> Hans Petter Selasky wrote:
>>>> On 2019-08-28 11:44, Yuri Pankov wrote:
>>>>> Hans Petter Selasky wrote:
>>>>>> On 2019-08-28 11:07, Yuri Pankov wrote:
>>>>>>> I have a "timed sleep before timers are working" panic in
>> ichsmb_readb()
>>>>>>> calling ichsmb_wait() which uses msleep().  That is trying to
>>>>>>> jedec_dimm(4) module so it's trying to attach pretty early in boot.
>>>>>>> What would be the correct replacement for msleep() here?
>>>>>>>
>>>>>>
>>>>>> If you only need a sleep-delay, pause() is the right one. It handles
>>>>>> cold-boot.
>>>>>
>>>>> I guess that won't work here as we need to be waked up by interrupt
>>>>> handler on command completion, and pause() seems to sleep
>>>>> unconditionally for the given time in 'cold' case (if I'm reading the
>>>>> code correctly).
>>>>
>>>> If you are too early inside a SYSINIT() path, then you cannot use
>>>> sleeping. You will have to use polling in a loop with a fixed DELAY()
>> to
>>>> know the timeout.
>>>
>>> Thanks for the help.
>>>
>>> Something like the following (it seems to work)?
>>
>> Here's a review with the nit you mentioned fixed, thanks!
>>
>> https://reviews.freebsd.org/D21452
> 
> 
> 
> What's the advantages of doing this instead of deferring attach until the
> interrupts are running?

None that I can think of, just going with what was suggested and seeing
other drivers doing the same.  Could you please name a driver that
defers attach until !cold?