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From 5918245d224a7a527052ed30af2627187777a282 Mon Sep 17 00:00:00 2001
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From: Richard Jones <rjones@redhat.com>
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Date: Wed, 1 Nov 2017 11:33:01 +0100
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Subject: [PATCH 6/7] i6300esb: fix timer overflow
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RH-Author: Richard Jones <rjones@redhat.com>
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Message-id: <1509535982-27927-3-git-send-email-rjones@redhat.com>
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Patchwork-id: 77460
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O-Subject: [RHEL-7.5 qemu-kvm PATCH v3 2/3] i6300esb: fix timer overflow
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Bugzilla: 1470244
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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RH-Acked-by: Thomas Huth <thuth@redhat.com>
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RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
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From: Laurent Vivier <lvivier@redhat.com>
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We use muldiv64() to compute the time to wait:
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timeout = muldiv64(get_ticks_per_sec(), timeout, 33000000);
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but get_ticks_per_sec() is 10^9 (30 bit value) and timeout
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is a 35 bit value.
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Whereas muldiv64 is:
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uint64_t muldiv64(uint64_t a, uint32_t b, uint32_t c)
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So we loose 3 bits of timeout.
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Swapping get_ticks_per_sec() and timeout fixes it.
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We can also replace it by a multiplication by 30 ns,
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but this changes PCI clock frequency from 33MHz to 33.333333MHz
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and we need to do this on all the QEMU PCI devices (later...)
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Signed-off-by: Laurent Vivier <lvivier@redhat.com>
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Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
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Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
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(cherry picked from commit fee562e9e41290a22623de83b673a8929ec5280d)
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BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1470244
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Upstream-status: fee562e9e41290a22623de83b673a8929ec5280d
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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hw/watchdog/wdt_i6300esb.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/hw/watchdog/wdt_i6300esb.c b/hw/watchdog/wdt_i6300esb.c
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index be35034..fa8e3b9 100644
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--- a/hw/watchdog/wdt_i6300esb.c
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+++ b/hw/watchdog/wdt_i6300esb.c
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@@ -132,7 +132,7 @@ static void i6300esb_restart_timer(I6300State *d, int stage)
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* multiply here can exceed 64-bits, before we divide by 33MHz, so
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* we use a higher-precision intermediate result.
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*/
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- timeout = muldiv64(get_ticks_per_sec(), timeout, 33000000);
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+ timeout = muldiv64(timeout, get_ticks_per_sec(), 33000000);
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i6300esb_debug("stage %d, timeout %" PRIi64 "\n", d->stage, timeout);
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--
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1.8.3.1
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