Messages in this thread | | | Subject | Re: [PATCH v1 3/3] Revert "Revert "driver core: Set fw_devlink=on by default"" | From | Florian Fainelli <> | Date | Tue, 27 Apr 2021 09:47:08 -0700 |
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On 4/27/2021 9:24 AM, Saravana Kannan wrote: > On Tue, Apr 27, 2021 at 8:10 AM Sudeep Holla <sudeep.holla@arm.com> wrote: >> >> On Tue, Apr 27, 2021 at 03:11:16PM +0100, Cristian Marussi wrote: >>> On Tue, Apr 27, 2021 at 09:33:31AM -0400, Jim Quinlan wrote: >> [...] >>>>> >>>> I believe that the brcmstb-mbox node is in our DT for backwards >>>> compatibility with our older Linux only. Note that we use the compatible >>>> string '"arm,scmi-smc", "arm,scmi"'; the former chooses SMC transport and >>>> ignores custom mailboxes such as brcmstb-mbox. >>>> >>> >>> Right..so it is even more wrong that it is waiting for the mailboxes...but >>> looking at the DT: >>> >>> brcm_scmi_mailbox@0 { >>> #mbox-cells = <0x01>; >>> compatible = "brcm,brcmstb-mbox"; >>> status = "disabled"; >>> linux,phandle = <0x04>; >>> phandle = <0x04>; >>> }; >>> >>> brcm_scmi@0 { >>> compatible = "arm,scmi-smc\0arm,scmi"; >>> mboxes = <0x04 0x00 0x04 0x01>; >>> mbox-names = "tx\0rx"; >>> shmem = <0x05>; >>> status = "disabled"; >>> arm,smc-id = <0x83000400>; >>> interrupt-names = "a2p"; >>> #address-cells = <0x01>; >>> #size-cells = <0x00>; >>> >>> it seems to me that even though you declare an SMC based transport (and in fact >>> you define the smc-id too) you also still define mboxes (as a fallback I suppose) >>> referring to the brcm_scmi_mailbox phandle, and while this is ignored by the SCMI >>> driver (because you have selected a compatible SMC transport) I imagine this dep >>> is picked up by fw_devlink which in fact says: >>> >>>> [ 0.300086] platform brcm_scmi@0: Linked as a consumer to brcm_scmi_mailbox@0 >>> >>> and stalls waiting for it. (but I'm not really familiar on how fw_devlink >>> internals works really...so I maybe off in these regards) > > Cristian, > > Great debugging work for not having worked on this before! Your > comments about the dependencies are right. If you grep the logs for > "probe deferral", you'll see these lines and more: > > [ 0.942998] platform brcm_scmi@0: probe deferral - supplier > brcm_scmi_mailbox@0 not ready > [ 3.622741] platform 8b20000.pcie: probe deferral - supplier > brcm_scmi@0 not ready > [ 5.695929] platform 840c000.serial: probe deferral - supplier > brcm_scmi@0 not ready > > Florian, > > Sorry I wasn't clear in my earlier email. I was asking for the path to > the board file DT in upstream so I could look at it and the files it > references. I didn't mean to ask for an "decompiled" DTS attachment. > The decompiled ones make it a pain to track the phandles.
Our Device Tree sources are not in the kernel since the bootloader provides a FDT to the kernel which is massaged in different ways to support a single binary for a multitude of reference boards and chip variants. That FDT is 90% auto-generated offline from scripts and about 10% runtime patched based on our whim. We should probably still aim for some visibility into these Device Tree files by the kernel community.
> > The part that's confusing to me is that the mbox node is disabled in > the DT you attached. fw_devlink is smart enough to ignore disabled > nodes. Is it getting enabled by the bootloader? Can you please try > deleting the reference to the brcm_scmi_mailbox from the scmi node and > see if it helps? Or leave it really disabled?
Removing the 'mboxes' phandle works, see my other reply to Sudeep and I should have captured the DT from the Linux prompt after it has been finalized and where the mbox node is marked as enabled unfortunately.
> > Also, as a separate test of workarounds, can you please add > deferred_probe_timeout=1 to your commandline and see if it helps? I'm > assuming you have modules enabled? Otherwise, the existing smarts in > fw_devlink to ignore devices with no drivers would have kicked in too.
deferred_probe_timeout=1 does help however all of these drivers are built into the kernel at the moment and so ultimately we reach user-space with no console driver registered.
> >> I was about to mention/ask the same when I saw Jim's reply. I see you have >> already asked that. Couple of my opinions based on my very limited knowledge >> on fw_devlink and how it works. >> >> 1. Since we have different compatible for SMC and mailbox, I am not sure >> if it correct to leave mailbox information in scmi node. Once we have >> proper yaml scheme, we must flag that error IMO. >> >> 2. IIUC, the fw_devlink might use information from DT to establish the >> dependency and having mailbox information in this context may be >> considered wrong as there is no dependency if it is using SMC. > > If this mbox reference from scmi is wrong for the current kernel and > never used, then I'd recommend deleting that.
Yes that seems to be the way forward unless we want to set fw_devlink=permissive on the command line, either should hopefully be an option.
Thanks a lot for your response! -- Florian
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