Hi Bjorn, Thanks for the details response. On Mon, May 18, 2020 at 06:29:27PM -0700, Bjorn Andersson wrote: > On Thu 14 May 22:17 PDT 2020, Viresh Kumar wrote: > [...] I find this part nicely summarise your response. > > - With serialization, if we use only one channel as today at every > > priority, if there are 5 requests to send signal to the receiver and > > the dvfs request is the last one in queue (which may be called from > > scheduler's hot path with fast switching), it unnecessarily needs to > > wait for the first four transfers to finish due to the software > > locking imposed by the mailbox framework. This adds additional delay, > > maybe of few ms only, which isn't required by the hardware but just by > > the software and few ms can be important in scheduler's hotpath. > > > > So these 5 requests, are they conveyed by the signals [1,2,3,4,5] or > [BIT(0), BIT(1), BIT(2), BIT(3), BIT(4)]? > Latter in this case. IMO it is platform choice on how to use it. It is equally possible to send 2^31 different signals. But the receiver must also interpret it in the *exact* same way. In this case, the receiver which is platform firmware interprets as individual bit signals. > In the first case you have to serialize things given that e.g. signal 1 > immediately followed by 2 is indistinguishable from 3. > Agree and we are not proposing to break that use case. It exists in the driver/binding today and will continue as is. > If you signals are single-bit notifications then you don't need any > serialization. > Indeed, we are making use of that. -- Regards, Sudeep
