lkml.org 
[lkml]   [2015]   [Jun]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/3] SLIMbus: Device management on SLIMbus
On 6/17/2015 5:45 AM, Mark Brown wrote:
> On Tue, Jun 16, 2015 at 09:22:31AM -0600, Sagar Dharia wrote:
>> On 6/15/2015 4:54 AM, Mark Brown wrote:
>>> On Sat, Jun 13, 2015 at 11:49:16PM -0600, Sagar Dharia wrote:
>>>> +void slim_ctrl_add_boarddevs(struct slim_controller *ctrl)
>>>> +{
>>> Why are these operations split?
>> Some slaves may choose to do expensive operations in their probes (or wait
>> for logical address assignment). That will delay/block controller
>> registration and further HW initialization of the controller.
>> I did not see any downside/side-effect in splitting them. I am open however
>> to have them combined if that's the preferred way.
> How does this resolve the issue? As far as I can see it just shuffles
> it around so any delay happens later (and possibly not at a convenient
> time), possibly not helping if there's multiple controllers. If devices
> are doing excessively expensive things in their probe that seems like
> something that we should fix in the drivers. For LA assignment
> shouldn't we be addressing that by having a callback when the LA is
> assigned? That will avoid single threading effects and is more like the
> pattern for other buses. Slimbus isn't particularly unique in this
> regard.
I agree that using the 'device_up' callback (it's called when the device
has LA assignment) will make sure slaves can keep their probes non-blocking.
I was just trying to accommodate that blocking call by slaves and did
not realize the downside you now mentioned about multiple-controllers
I will combine these in next patchset.
Thanks
Sagar
>
> Greg, the LA assignment thing here is an example of the issue is an
> example of the pattern I raised a while ago (but never got round to
> coding up handling of) where we have devices on an enumerable bus with
> static registrations. LA assignment is the end of the hotplug process
> for a Slimbus device but most devices will need something doing to power
> them up so they enumerate.


--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation



\
 
 \ /
  Last update: 2015-06-17 19:41    [W:0.049 / U:0.220 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site