From: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
To: Finn Thain <fthain@linux-m68k.org>,
David Gibson <david@gibson.dropbear.id.au>,
Greg Kurz <groug@kaod.org>
Cc: qemu-ppc@nongnu.org, Laurent Vivier <laurent@vivier.eu>,
qemu-devel@nongnu.org
Subject: Re: [RFC 01/10] hw/mos6522: Remove get_load_time() methods and functions
Date: Wed, 25 Aug 2021 07:55:14 +0100 [thread overview]
Message-ID: <ee403f8a-2fde-56cd-789f-a2ab7f35eb00@ilande.co.uk> (raw)
In-Reply-To: <9b78e8c6e453feab6275d04bf503051645770d85.1629799776.git.fthain@linux-m68k.org>
On 24/08/2021 11:09, Finn Thain wrote:
> This code appears to be unnecessary.
>
> Signed-off-by: Finn Thain <fthain@linux-m68k.org>
> ---
> hw/misc/mos6522.c | 22 +---------------------
> 1 file changed, 1 insertion(+), 21 deletions(-)
>
> diff --git a/hw/misc/mos6522.c b/hw/misc/mos6522.c
> index 1c57332b40..a478c1ca43 100644
> --- a/hw/misc/mos6522.c
> +++ b/hw/misc/mos6522.c
> @@ -63,17 +63,6 @@ static uint64_t get_counter_value(MOS6522State *s, MOS6522Timer *ti)
> }
> }
>
> -static uint64_t get_load_time(MOS6522State *s, MOS6522Timer *ti)
> -{
> - MOS6522DeviceClass *mdc = MOS6522_GET_CLASS(s);
> -
> - if (ti->index == 0) {
> - return mdc->get_timer1_load_time(s, ti);
> - } else {
> - return mdc->get_timer2_load_time(s, ti);
> - }
> -}
> -
> static unsigned int get_counter(MOS6522State *s, MOS6522Timer *ti)
> {
> int64_t d;
> @@ -98,7 +87,7 @@ static unsigned int get_counter(MOS6522State *s, MOS6522Timer *ti)
> static void set_counter(MOS6522State *s, MOS6522Timer *ti, unsigned int val)
> {
> trace_mos6522_set_counter(1 + ti->index, val);
> - ti->load_time = get_load_time(s, ti);
> + ti->load_time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
> ti->counter_value = val;
> if (ti->index == 0) {
> mos6522_timer1_update(s, ti, ti->load_time);
> @@ -208,13 +197,6 @@ static uint64_t mos6522_get_counter_value(MOS6522State *s, MOS6522Timer *ti)
> ti->frequency, NANOSECONDS_PER_SECOND);
> }
>
> -static uint64_t mos6522_get_load_time(MOS6522State *s, MOS6522Timer *ti)
> -{
> - uint64_t load_time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
> -
> - return load_time;
> -}
> -
> static void mos6522_portA_write(MOS6522State *s)
> {
> qemu_log_mask(LOG_UNIMP, "portA_write unimplemented\n");
> @@ -518,8 +500,6 @@ static void mos6522_class_init(ObjectClass *oc, void *data)
> mdc->update_irq = mos6522_update_irq;
> mdc->get_timer1_counter_value = mos6522_get_counter_value;
> mdc->get_timer2_counter_value = mos6522_get_counter_value;
> - mdc->get_timer1_load_time = mos6522_get_load_time;
> - mdc->get_timer2_load_time = mos6522_get_load_time;
> }
>
> static const TypeInfo mos6522_type_info = {
Both the get_counter_value() and get_load_time() callbacks are used as part of the
CUDA emulation in hw/misc/macio/cuda.c as per the comment:
/* MacOS uses timer 1 for calibration on startup, so we use
* the timebase frequency and cuda_get_counter_value() with
* cuda_get_load_time() to steer MacOS to calculate calibrate its timers
* correctly for both TCG and KVM (see commit b981289c49 "PPC: Cuda: Use cuda
* timer to expose tbfreq to guest" for more information) */
Certainly for the 6522 device it is worth configuring with --target-list="ppc-softmmu
m68k-softmmu" to make sure that you don't inadvertently break anything in the PPC world.
A bit of history here: the original mos6522.c was extracted from hw/misc/macio/cuda.c
when Laurent presented his initial q800 patches since they also had their own
implementation of the 6522, and it was better to move the implementation into a
separate QEMU device so that the logic could be shared.
The Darwin kernel timer calibration loop is quite hard to get right: see
https://opensource.apple.com/source/xnu/xnu-123.5/pexpert/ppc/pe_clock_speed_asm.s.auto.html
and
https://opensource.apple.com/source/xnu/xnu-123.5/pexpert/ppc/pe_clock_speed.c.auto.html.
Ben/Alex came up with the current mechanism to fool the calibration routine, and I
simply added in those callbacks to allow it to be implemented as part of the
now-generic 6522 device.
ATB,
Mark.
next prev parent reply other threads:[~2021-08-25 6:56 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-24 10:09 [RFC 00/10] hw/mos6522: VIA timer emulation fixes and improvements Finn Thain
2021-08-24 10:09 ` [RFC 09/10] hw/mos6522: Avoid using discrepant QEMU clock values Finn Thain
2021-08-24 10:28 ` Philippe Mathieu-Daudé
2021-08-29 1:23 ` Finn Thain
2021-08-25 8:44 ` Mark Cave-Ayland
2021-08-29 1:55 ` Finn Thain
2021-08-24 10:09 ` [RFC 06/10] hw/mos6522: Implement oneshot mode Finn Thain
2021-08-25 8:18 ` Mark Cave-Ayland
2021-08-29 1:20 ` Finn Thain
2021-08-24 10:09 ` [RFC 01/10] hw/mos6522: Remove get_load_time() methods and functions Finn Thain
2021-08-24 10:29 ` Philippe Mathieu-Daudé
2021-08-25 6:55 ` Mark Cave-Ayland [this message]
2021-08-28 1:00 ` Finn Thain
2021-08-24 10:09 ` [RFC 08/10] hw/mos6522: Call mos6522_update_irq() when appropriate Finn Thain
2021-08-24 10:22 ` Philippe Mathieu-Daudé
2021-08-25 8:26 ` Mark Cave-Ayland
2021-08-24 10:09 ` [RFC 07/10] hw/mos6522: Fix initial timer counter reload Finn Thain
2021-08-25 8:23 ` Mark Cave-Ayland
2021-08-28 0:46 ` Finn Thain
2021-08-24 10:09 ` [RFC 10/10] hw/mos6522: Synchronize timer interrupt and timer counter Finn Thain
2021-08-25 8:52 ` Mark Cave-Ayland
2021-08-26 6:43 ` Finn Thain
2021-08-24 10:09 ` [RFC 04/10] hw/mos6522: Rename timer callback functions Finn Thain
2021-08-24 10:28 ` Philippe Mathieu-Daudé
2021-08-25 7:11 ` Mark Cave-Ayland
2021-08-26 7:42 ` Philippe Mathieu-Daudé
2021-08-24 10:09 ` [RFC 02/10] hw/mos6522: Remove get_counter_value() methods and functions Finn Thain
2021-08-24 10:29 ` Philippe Mathieu-Daudé
2021-08-24 10:09 ` [RFC 05/10] hw/mos6522: Don't clear T1 interrupt flag on latch write Finn Thain
2021-08-25 7:20 ` Mark Cave-Ayland
2021-08-26 5:21 ` Finn Thain
2021-09-01 14:32 ` Laurent Vivier
2021-09-01 22:26 ` Finn Thain
2021-08-24 10:09 ` [RFC 03/10] hw/mos6522: Remove redundant mos6522_timer1_update() calls Finn Thain
2021-08-25 7:09 ` Mark Cave-Ayland
2021-08-24 10:34 ` [RFC 00/10] hw/mos6522: VIA timer emulation fixes and improvements Philippe Mathieu-Daudé
2021-08-28 1:22 ` Finn Thain
2021-08-31 21:14 ` Mark Cave-Ayland
2021-08-31 22:44 ` Finn Thain
2021-09-01 7:57 ` Mark Cave-Ayland
2021-09-01 8:06 ` Mark Cave-Ayland
2021-09-10 17:29 ` Mark Cave-Ayland
2021-09-11 0:08 ` Finn Thain
2021-09-01 2:20 ` Finn Thain
2021-08-25 3:11 ` David Gibson
2021-08-25 9:10 ` Mark Cave-Ayland
2021-08-28 4:11 ` Finn Thain
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