Re: [Qemu-devel] [PATCH v2 2/3] audio: use object link instead ofqdev property to pass wm8750 reference

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

Cc'ing Eduardo and Thomas.

On 12/10/2018 13:51, maozy wrote:
> Hi, Philippe
> 
> On 10/12/18 5:53 PM, Philippe Mathieu-Daudé wrote:
>> Hi Mao,
>>
>> On 12/10/2018 10:30, Mao Zhongyi wrote:
>>> According to qdev-properties.h, properties of pointer type should
>>> be avoided, it seems a link type property is a good substitution.
>>>
>>> Cc: Jan Kiszka <jan.kiszka@web.de>
>>> Cc: Peter Maydell <peter.maydell@linaro.org>
>>> Cc: Gerd Hoffmann <kraxel@redhat.com>
>>> To: qemu-arm@nongnu.org
>>>
>>> Signed-off-by: Mao Zhongyi <maozhongyi@cmss.chinamobile.com>
>>> ---
>>>   hw/arm/musicpal.c          |  3 ++-
>>>   hw/audio/marvell_88w8618.c | 14 ++++++--------
>>>   2 files changed, 8 insertions(+), 9 deletions(-)
>>>
>>> diff --git a/hw/arm/musicpal.c b/hw/arm/musicpal.c
>>> index 3dafb41b0b..ac266f9253 100644
>>> --- a/hw/arm/musicpal.c
>>> +++ b/hw/arm/musicpal.c
>>> @@ -1695,7 +1695,8 @@ static void musicpal_init(MachineState *machine)
>>>       wm8750_dev = i2c_create_slave(i2c, TYPE_WM8750, MP_WM_ADDR);
>>>       dev = qdev_create(NULL, "mv88w8618_audio");
>>>       s = SYS_BUS_DEVICE(dev);
>>> -    qdev_prop_set_ptr(dev, TYPE_WM8750, wm8750_dev);
>>> +    object_property_set_link(OBJECT(dev), OBJECT(wm8750_dev),
>>> +                             TYPE_WM8750, NULL);
>>>       qdev_init_nofail(dev);
>>>       sysbus_mmio_map(s, 0, MP_AUDIO_BASE);
>>>       sysbus_connect_irq(s, 0, pic[MP_AUDIO_IRQ]);
>>> diff --git a/hw/audio/marvell_88w8618.c b/hw/audio/marvell_88w8618.c
>>> index cf6ce6979b..baab4a3d53 100644
>>> --- a/hw/audio/marvell_88w8618.c
>>> +++ b/hw/audio/marvell_88w8618.c
>>> @@ -15,6 +15,7 @@
>>>   #include "hw/i2c/i2c.h"
>>>   #include "hw/audio/wm8750.h"
>>>   #include "audio/audio.h"
>>> +#include "qapi/error.h"
>>>     #define MP_AUDIO_SIZE           0x00001000
>>>   @@ -252,6 +253,11 @@ static void mv88w8618_audio_init(Object *obj)
>>>       memory_region_init_io(&s->iomem, obj, &mv88w8618_audio_ops, s,
>>>                             "audio", MP_AUDIO_SIZE);
>>>       sysbus_init_mmio(dev, &s->iomem);
>>> +
>>> +    object_property_add_link(OBJECT(dev), "mv88w8618", TYPE_WM8750,
>>> +                             (Object **) &s->wm,
>>> +                             qdev_prop_allow_set_link_before_realize,
>>> +                             0, &error_abort);
>>>   }
>>>     static void mv88w8618_audio_realize(DeviceState *dev, Error **errp)
>>> @@ -279,11 +285,6 @@ static const VMStateDescription
>>> mv88w8618_audio_vmsd = {
>>>       }
>>>   };
>>>   -static Property mv88w8618_audio_properties[] = {
>>> -    DEFINE_PROP_PTR(TYPE_WM8750, mv88w8618_audio_state, wm),
>>> -    {/* end of list */},
>>> -};
>>> -
>>>   static void mv88w8618_audio_class_init(ObjectClass *klass, void *data)
>>>   {
>>>       DeviceClass *dc = DEVICE_CLASS(klass);
>>> @@ -291,9 +292,6 @@ static void
>>> mv88w8618_audio_class_init(ObjectClass *klass, void *data)
>>>       dc->realize = mv88w8618_audio_realize;
>>>       dc->reset = mv88w8618_audio_reset;
>>>       dc->vmsd = &mv88w8618_audio_vmsd;
>>> -    dc->props = mv88w8618_audio_properties;
>>> -    /* Reason: pointer property "wm8750" */
>>> -    dc->user_creatable = false;
>>
>> Having a link property isn't it the same restriction?
> 
> This task can found in
> https://wiki.qemu.org/Contribute/BiteSizedTasks#Device_models
> 
> Convert qdev pointer properties (defined with DEFINE_PROP_PTR) to QOM
> links. Example: commit 873b4d3.

I agree with the QOM conversion (the rest of this patch), what I'm
wondering is if declaring this device now user_creatable is correct. I
don't think we can set link property from command line, but maybe I'm
wrong because I never investigate/tried to do it.

Maybe devices having link property are automatically marked as
user_creatable = false, then your change would be correct (except you
should explicit that in the commit message).

I'll post another mail on the list to ask about that.

Regards,

Phil.

> 
> Thanks,
> Mao
> 
>>
>>>   }
>>>     static const TypeInfo mv88w8618_audio_info = {
>>>
>>
> 
>