Messages in this thread | | | Date | Mon, 31 Jul 2023 07:04:26 -0700 | Subject | Re: [PATCH v2 3/3] firmware: arm_scmi: Add qcom hvc/shmem transport | From | Nikunj Kela <> |
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On 7/25/2023 10:12 AM, Nikunj Kela wrote: > > On 7/25/2023 10:03 AM, Cristian Marussi wrote: >> On Mon, Jul 24, 2023 at 09:44:19AM -0700, Nikunj Kela wrote: >>> Add a new transport channel to the SCMI firmware interface driver for >>> SCMI message exchange on Qualcomm virtual platforms. >>> >>> The hypervisor associates an object-id also known as capability-id >>> with each hvc doorbell object. The capability-id is used to identify >>> the >>> doorbell from the VM's capability namespace, similar to a >>> file-descriptor. >>> >>> The hypervisor, in addition to the function-id, expects the >>> capability-id >>> to be passed in x1 register when HVC call is invoked. >>> >>> The qcom hvc doorbell/shared memory transport uses a statically defined >>> shared memory region that binds with "arm,scmi-shmem" device tree node. >>> >>> The function-id & capability-id are allocated by the hypervisor on >>> bootup >>> and are stored in the shmem region by the firmware before starting >>> Linux. >>> >>> Currently, there is no usecase for the atomic support therefore this >>> driver >>> doesn't include the changes for the same. >>> >> Hi Nikunj, >> >> so basically this new SCMI transport that you are introducing is just >> exactly like the existing SMC transport with the only difference that >> you introduced even another new way to configure func_id, a new cap_id >> param AND the fact that you use HVC instead of SMC... all of this tied >> to a new compatible to identify this new transport mechanism.... >> ..but all in all is just a lot of plain duplicated code to maintain... >> >> ...why can't you fit this other smc/hvc transport variant into the >> existing SMC transport by properly picking and configuring >> func_id/cap_id >> and "doorbell" method (SMC vs HVC) in the chan_setup() step ? >> >> ..I mean ... you can decide where to pick your params based on >> compatibles and also you can setup your invokation method (SMC vs HVC) >> based on those...while keeping all the other stuff exactly the same... >> ...including support for atomic exchanges...if not, when you'll need >> that >> too in your QC_HVC transport you'll have to duplicate also that (and my >> bugs too probably :P) >> >> (... well maybe in this scenario also the transport itself should be >> renamed from SMC to something more general...) >> >> Not sure if I am missing something, or if Sudeep will be horrified by >> this unifying proposal of mine, but in this series as it stands now I >> just see a lot of brutally duplicated stuff that just differs by naming >> and a very minimal change in logic that could be addressed changing and >> generalizing the original SMC transport code instead. >> >> Thanks, >> Cristian > > Hi Christian, > > I totally agree with you and will be happy to include my changes in > smc.c if Sudeep agrees with that approach. > > Thanks
Hi Sudeep, Could you please provide your feedback on this? Thanks
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