Hi Prashanth, On Wed, Jun 8, 2016 at 5:32 PM, Prakash, Prashanth <pprakash@xxxxxxxxxxxxxx> wrote: > > > On 6/8/2016 10:24 AM, Hoan Tran wrote: >> Hi Ashwin, >> >> On Wed, Jun 8, 2016 at 5:18 AM, Ashwin Chaugule >> <ashwin.chaugule@xxxxxxxxxx> wrote: >>> + Prashanth (Can you please have a look as well?) >>> >>> On 31 May 2016 at 15:35, Hoan Tran <hotran@xxxxxxx> wrote: >>>> Hi Ashwin, >>> Hi, >>> >>> Sorry about the delay. I'm in the middle of switching jobs and >>> locations, so its been a bit crazy lately. >> It's ok and hope you're doing well. >> >>> I dont have any major >>> concerns with this code, although there could be subtle issues with >>> this IRQ thing. In this patchset, your intent is to add support for >>> PCC subspace type 2. But you're also adding support for tx command >>> completion which is not specific to Type 2. We could support that even >>> in Type 1. Hence I wanted to separate the two, not just for review, >>> but also the async IRQ completion has subtle issues esp. in the case >>> of async platform notification, where you could have a PCC client in >>> the OS writing to the cmd bit and the platform sending an async >>> notification by writing to some bits in the same 8byte address as the >>> cmd bit. So we need some mutual exclusivity there, otherwise the OS >>> and platform could step on each other. Perhaps Prashanth has better >>> insight into this. >> I think, this mutual exclusivity could be in another patch. > Ashwin, > Sorry, I am not sure how we can prevent platform and OSPM from stepping on > each other. There is a line is spec that says "all operations on status field > must be made using interlocked operations", but not sure what these > interlocked operation translates to. Yes, I had the same question about how to prevent it. > > Hoan, > Even if we are not using platform notification, we still need to clear the doorbell > interrupt bit in the PCC interrupt handler (Section14.2.2 and 14.4). I didn't see > clearing the doorbell interrupt bit in this patch (and platform is supposed to set > it again when it is sending the interrupt again). Did I miss it? or is it intentionally > left out to avoid the race that Ashwin mentioned above? > The PCC client driver is supposed to do that. Which mean, the mbox_chan_received_data() function should clear it. Thanks Hoan > > Thanks, > Prashanth > > -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
