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envelope-from=laurent@vivier.eu; helo=mout.kundenserver.de X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Le 10/03/2021 à 14:10, Laurent Vivier a écrit : > Le 10/03/2021 à 13:56, Laurent Vivier a écrit : >> Le 10/03/2021 à 13:32, BALATON Zoltan a écrit : >>> On Wed, 10 Mar 2021, Mark Cave-Ayland wrote: >>>> The 60Hz timer is initialised using timer_new_ns() meaning that the timer >>>> interval should be measured in ns, and therefore its period is a thousand >>>> times too short. >>>> >>>> Signed-off-by: Mark Cave-Ayland >>>> --- >>>> hw/misc/mac_via.c | 4 ++-- >>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/hw/misc/mac_via.c b/hw/misc/mac_via.c >>>> index f994fefa7c..c6e1552a59 100644 >>>> --- a/hw/misc/mac_via.c >>>> +++ b/hw/misc/mac_via.c >>>> @@ -302,8 +302,8 @@ static void via1_sixty_hz_update(MOS6522Q800VIA1State *v1s) >>>>     MOS6522State *s = MOS6522(v1s); >>>> >>>>     /* 60 Hz irq */ >>>> -    v1s->next_sixty_hz = (qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + 16630) / >>>> -                          16630 * 16630; >>>> +    v1s->next_sixty_hz = (qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + 16630000) / >>>> +                          16630000 * 16630000; >>> >>> Can you put this magic number in a #define maybe also rewriting it in a way that shows it >>> corresponds to a 60 Hz interval. (There's NANOSECONDS_PER_SECOND defined in include/qemu/timer.h >>> that could be used for that, there's also SCALE_MS that might replace 1000 * 1000 elsewhere in this >>> file). Also NANOSECONDS_PER_SECOND / 60 is 16666666, should that value be used here instead? >> >> In fact, the Mac Frequency is not exactly 60 Hz, in docs we can find 60.147 Hz, in kernel 60.15 Hz. >> I Think there are several ways to compute it... >> > > In fact, we can read: > > "the vertical retrace frequency is approximately 60.15 Hz, resulting in a period of approximately > 16.63 milliseconds" > > https://developer.apple.com/library/archive/documentation/mac/pdf/Processes/Vertical_Retrace_Mgr.pdf The exact value is 16625800 ns "Macintosh Family Hardware Reference" ISBN 0-201-19255-1 "The video interface" p. 13-3 "[...] This means the full frame is redisplayed every 370 scan lines, or once every 166625.8 µs." Thanks, Laurent