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From: | Václav Vanc |
Subject: | Re: [PATCH] hw/timer/a9gtimer: Clear pending interrupt, after the clear of Event flag |
Date: | Thu, 9 Jul 2020 14:16:12 +0200 |
On 6/26/20 4:46 PM, Peter Maydell wrote:
On Tue, 16 Jun 2020 at 08:04, Václav Vanc <vav@sysgo.com> wrote:On 6/15/20 1:04 PM, Peter Maydell wrote: We must distinguish between two cases: 1, Auto-increment is disabled. I just run some test on SABRE Lite (i.MX6) board. I had auto-increment disabled, I verified, that GIC is configured for Edge interrupts. Once count went past the compare value I got the interrupt. I did not touch Timer registers, just signal EOI to GIC and surprisingly, I got a another interrupt. If I stopped the timer interrupts stopped coming (Status was still set to 1). From this behavior I assume, that every time the Timer is incremented (and Timer value is past the compare value) an EDGE interrupt (that means actual X->0->1 transition) is asserted. This is really interesting from HW point of view. This would mean, that a9_gtimer_update function should generate the pulse and not level on compare event.That's interesting. Which version of the Cortex-A9 does this board have? The TRM documents that the comparator behaviour changed in r2p0... thanks -- PMM
It is "SABRE Lite (i.MX6)" board with Cortex-A9 r2p10.Behavior is also the same for "Xilinx Zynq-7000 SoC ZC702 Evaluation Kit" with Cortex-A9 r3p0.
Unfortunately I do not have any board with older revision of Cortex-A9. Best Regards, Ing. Václav Vanc Project Engineer SYSGO s.r.o. Embedding Innovations Research and Development Center Prague Zeleny pruh 1560/99 I CZ-14000 Praha 4 Phone: +420 222138 828, +49 6136 9948 828 Fax: +420 244911174 E-mail: vaclav.vanc@sysgo.com _________________________________________________________________________________ Web: https://www.sysgo.com Blog: https://www.sysgo.com/blog Events: https://www.sysgo.com/events Newsletter: https://www.sysgo.com/newsletter _________________________________________________________________________________ Handelsregister/Commercial Registry: HRB Mainz 90 HRB 48884Geschäftsführung/Managing Directors: Etienne Butery (CEO), Kai Sablotny (COO)
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