From: "Andrei Warkentin" <awarkentin@vmware.com>
To: Andrei Warkentin <andrey.warkentin@gmail.com>,
"devel@edk2.groups.io" <devel@edk2.groups.io>,
"ard.biesheuvel@arm.com" <ard.biesheuvel@arm.com>
Cc: "leif@nuviainc.com" <leif@nuviainc.com>,
"pete@akeo.ie" <pete@akeo.ie>,
"philmd@redhat.com" <philmd@redhat.com>
Subject: Re: [edk2-devel] [edk2-platforms][PATCH 1/1] Pi4: notify VPU to load xHCI firmware before XhciDxe binds
Date: Mon, 1 Jun 2020 09:37:59 +0000 [thread overview]
Message-ID: <BN6PR05MB341168A240AACAB7D4E40A44B98A0@BN6PR05MB3411.namprd05.prod.outlook.com> (raw)
In-Reply-To: <3121e7a6-afb7-038e-4fcd-5a317d3194e9@arm.com>
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Hi Ard,
The xHCI controller is initialized with its microcode by the VPU firmware, if
I understood correctly, synchronously. When RPI_MBOX_NOTIFY_XHCI_RESET finishes, the XHCI controller is ready to go.
So this is not any more unsafe than any of the other mailbox calls. To be honest, I think RpiFirmwareDxe should be cleaned up to replace the useless spinlocks (there's no multiprocessing component) with a TPL manip (I checked SynchonizationLib and it doesn't touch the TPL)
Applying your other feedback now...
A
________________________________
From: devel@edk2.groups.io <devel@edk2.groups.io> on behalf of Ard Biesheuvel via groups.io <ard.biesheuvel=arm.com@groups.io>
> +
> + Status = MailboxTransaction (Cmd->BufferHead.BufferSize, RPI_MBOX_VC_CHANNEL, &Result);
> +
So this pokes the XHCI controller via its config space? Is it safe to do
that without raising the TPL? What happens if another config space
access occurs concurrently?
A
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next prev parent reply other threads:[~2020-06-01 9:38 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-01 3:21 [edk2-platforms][PATCH 1/1] Pi4: notify VPU to load xHCI firmware before XhciDxe binds Andrei Warkentin
2020-06-01 6:59 ` Ard Biesheuvel
2020-06-01 9:37 ` Andrei Warkentin [this message]
2020-06-01 9:44 ` [edk2-devel] " Ard Biesheuvel
2020-06-01 9:48 ` Andrei Warkentin
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