On 3/6/2020 3:48 AM, Doug Anderson wrote: > Hi, > > On Thu, Mar 5, 2020 at 1:41 AM Maulik Shah <mkshah@xxxxxxxxxxxxxx> wrote: > >> There are other cases like below which also gets impacted if driver >>>> don't cache anything... >>>> >>>> for example, when we don’t have dedicated ACTIVE TCS ( if we have below >>>> config with ACTIVE TCS count 0) >>>> qcom,tcs-config = <ACTIVE_TCS 0>, >>>> <SLEEP_TCS 3>, >>>> <WAKE_TCS 3>, >>>> >>>> Now to send active data, driver may re-use/ re-purpose few of the sleep >>>> or wake TCS, to be used as ACTIVE TCS and once work is done, >>>> it will be re-allocated in SLEEP/ WAKE TCS pool accordingly. If driver >>>> don’t cache, all the SLEEP and WAKE data is lost when one >>>> of TCS is repurposed to use as ACTIVE TCS. >>> Ah, interesting. I'll read the code more, but are you expecting this >>> type of situation to work today, or is it theoretical for the future? >> yes, we have targets which needs to work with this type of situation. > My brain is still slowly absorbing all the code, but something tells > me that targets with no ACTIVE TCS will not work properly with non-OSI > mode unless you change your patches more. Specifically to make the > zero ACTIVE TCS case work I think you need a rpmh_flush() call after > _ALL_ calls to rpmh_write() and rpmh_write_batch() (even those > modifying ACTIVE state). rpmh_write_async() will be yet more > interesting because you'd have to flush in rpmh_tx_done() I guess? > ...and also somehow you need to inhibit entering sleep mode if an > async write was in progress? Maybe easier to just detect the > "non-OSI-mode + 0 ACTIVE TCS" case at probe time and fail to probe? > > > -Doug No, it shouldn’t break with "non-OSI-mode + 0 ACTIVE TCS" After taking your suggestion to do rpmh start/end transaction in v13, rpmh_end_transaction() invokes rpmh_flush() only for the last client and by this time expecting all of rpmh_write() and rpmh_write_batch() will be already “finished” as client first waits for them to finish and then only invokes end. So driver is good to handle rpmh_write() and rpmh_write_batch() calls. Regarding rpmh_write_async() call, which is a fire-n-forget request from SW and client driver may immediately invoke rpmh_end_transaction() after this. this case is also handled… Lets again take an example for understanding this.. 1. Client invokes rpmh_write_async() to send ACTIVE cmds for targets which has zero ACTIVE TCS Rpmh driver Re-purposes one of SLEEP/WAKE TCS to use as ACTIVE, internally this also sets drv->tcs_in_use to true for respective SLEEP/WAKE TCS. 2. Client now without waiting for above to finish, goes ahead and invokes rpmh_end_transaction() which calls rpmh_flush() (in case cache become dirty) Now if re-purposed TCS is still in use in HW (transaction in progress), we still have drv->tcs_in_use set. So the rpmh_rsc_invalidate() (invoked from rpmh_flush()) will keep on returning -EAGAIN until that TCS becomes free to use and then goes ahead to finish its job. Thanks, Maulik -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation
