Hi Michael, I agree that XhcGetElapsedTime() would be better off in TimerLib, but I wasn't sure how the community would feel about adding to the interface.
As for your question, I was wondering the same thing, I'm not sure if there are any platforms that do not have a free-running timer that would be accessed through TimerLib. Because of this unknown I included a check on the return value from XhcGetElapsedTime(), if that value is 0 ElapsedTime is incremented regardless to avoid a potential hang. The behavior of the function essentially reverts to the pre "MdeModulePkg/XhciDxe: Fix Broken Timeouts" commit implementation. Thanks, Patrick Henz -----Original Message----- From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Michael Brown Sent: Thursday, July 6, 2023 8:02 AM To: devel@edk2.groups.io; Henz, Patrick <patrick.h...@hpe.com> Subject: Re: [edk2-devel] [PATCH] MdeModulePkg/XhciDxe: Use Performance Timer for XHCI Timeouts On 05/07/2023 21:15, Henz, Patrick wrote: > REF:INVALID URI REMOVED > g.cgi?id=2948__;!!NpxR!mnYVFUERkrUcRiNbM7pejt6qy6h5tilkuGydeM0skcGMAzS > 1oEy1DSDT720vj4Le2cGtf_kmPYFIng$ > > XhciDxe uses the timer functionality provided by the boot services > table to detect timeout conditions. This breaks the driver's > ExitBootServices call back, as CoreExitBootServices halts the timer > before signaling the ExitBootServices event. If the host controller > fails to halt in the call back, the timeout condition will never occur > and the boot gets stuck in an indefinite spin loop. Use the free > running timer provided by TimerLib to calculate timeouts, avoiding the > potential hang. Two points: 1. The XhcGetElapsedTime() function feels like a generally reusable abstraction that should exist within TimerLib, rather than being open-coded within XhciDxe. 2. Is the performance counter guaranteed to exist and work as expected on all platforms and CPU architectures? (For example: what if the CPU does not support a constant TSC?) Thanks, Michael -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#106702): https://edk2.groups.io/g/devel/message/106702 Mute This Topic: https://groups.io/mt/99972791/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
