[v2,02/24] display/xlnx_dp: Fix to realize "i2c-ddc" and "aux-to-i2c-bridge"

Commit Message

Markus Armbruster May 28, 2020, 11:04 a.m. UTC

xlnx_dp_init() creates these two devices, but they're never realized.
Affects machine xlnx-zcu102.

In theory, a device becomes real only on realize.  In practice, the
transition from unreal to real is a fuzzy one.  The work to make a
device real can be spread between realize methods (fine),
instance_init methods (wrong), and board code wiring up the device
(fine as long as it effectively happens on realize).  Depending on
what exactly is done where, a device can work even when we neglect to
realize it.

These two appear to work.  Nevertheless, it's a clear misuse of the
interface.  Even when it works today (more or less by chance), it can
break tomorrow.

Fix by realizing them in xlnx_dp_realize().

Fixes: 58ac482a66de09a7590f705e53fc6a3fb8a055e8
Cc: KONRAD Frederic <[e-mail]>
Cc: Alistair Francis <[e-mail]>
Cc: "Edgar E. Iglesias" <[e-mail]>
Cc: Peter Maydell <[e-mail]>
Cc: [e-mail]
Signed-off-by: Markus Armbruster <[e-mail]>
Reviewed-by: Edgar E. Iglesias <[e-mail]>
Reviewed-by: Alistair Francis <[e-mail]>
---
 hw/display/xlnx_dp.c | 4 ++++
 1 file changed, 4 insertions(+)

Comments

Philippe Mathieu-Daudé June 8, 2020, 2:16 p.m. UTC | #1

On 5/28/20 1:04 PM, Markus Armbruster wrote:
> xlnx_dp_init() creates these two devices, but they're never realized.
> Affects machine xlnx-zcu102.
> 
> In theory, a device becomes real only on realize.  In practice, the
> transition from unreal to real is a fuzzy one.  The work to make a
> device real can be spread between realize methods (fine),
> instance_init methods (wrong), and board code wiring up the device
> (fine as long as it effectively happens on realize).  Depending on
> what exactly is done where, a device can work even when we neglect to
> realize it.
> 
> These two appear to work.  Nevertheless, it's a clear misuse of the
> interface.  Even when it works today (more or less by chance), it can
> break tomorrow.
> 
> Fix by realizing them in xlnx_dp_realize().
> 
> Fixes: 58ac482a66de09a7590f705e53fc6a3fb8a055e8
> Cc: KONRAD Frederic <[e-mail]>
> Cc: Alistair Francis <[e-mail]>
> Cc: "Edgar E. Iglesias" <[e-mail]>
> Cc: Peter Maydell <[e-mail]>
> Cc: [e-mail]
> Signed-off-by: Markus Armbruster <[e-mail]>
> Reviewed-by: Edgar E. Iglesias <[e-mail]>
> Reviewed-by: Alistair Francis <[e-mail]>
> ---
>  hw/display/xlnx_dp.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/hw/display/xlnx_dp.c b/hw/display/xlnx_dp.c
> index 3e5fb44e06..bdc229a51e 100644
> --- a/hw/display/xlnx_dp.c
> +++ b/hw/display/xlnx_dp.c
> @@ -1264,9 +1264,13 @@ static void xlnx_dp_realize(DeviceState *dev, Error **errp)
>      DisplaySurface *surface;
>      struct audsettings as;
>  
> +    qdev_init_nofail(DEVICE(s->aux_bus->bridge));

Eh??? Why not realize the bridge in aux_init_bus()?

> +
>      qdev_init_nofail(DEVICE(s->dpcd));
>      aux_map_slave(AUX_SLAVE(s->dpcd), 0x0000);
>  
> +    qdev_init_nofail(DEVICE(s->edid));

This one is OK.

> +
>      s->console = graphic_console_init(dev, 0, &xlnx_dp_gfx_ops, s);
>      surface = qemu_console_surface(s->console);
>      xlnx_dpdma_set_host_data_location(s->dpdma, DP_GRAPHIC_DMA_CHANNEL,
>

Markus Armbruster June 9, 2020, 5:38 a.m. UTC | #2

Philippe Mathieu-Daudé <[e-mail]> writes:

> On 5/28/20 1:04 PM, Markus Armbruster wrote:
>> xlnx_dp_init() creates these two devices, but they're never realized.
>> Affects machine xlnx-zcu102.
>> 
>> In theory, a device becomes real only on realize.  In practice, the
>> transition from unreal to real is a fuzzy one.  The work to make a
>> device real can be spread between realize methods (fine),
>> instance_init methods (wrong), and board code wiring up the device
>> (fine as long as it effectively happens on realize).  Depending on
>> what exactly is done where, a device can work even when we neglect to
>> realize it.
>> 
>> These two appear to work.  Nevertheless, it's a clear misuse of the
>> interface.  Even when it works today (more or less by chance), it can
>> break tomorrow.
>> 
>> Fix by realizing them in xlnx_dp_realize().
>> 
>> Fixes: 58ac482a66de09a7590f705e53fc6a3fb8a055e8
>> Cc: KONRAD Frederic <[e-mail]>
>> Cc: Alistair Francis <[e-mail]>
>> Cc: "Edgar E. Iglesias" <[e-mail]>
>> Cc: Peter Maydell <[e-mail]>
>> Cc: [e-mail]
>> Signed-off-by: Markus Armbruster <[e-mail]>
>> Reviewed-by: Edgar E. Iglesias <[e-mail]>
>> Reviewed-by: Alistair Francis <[e-mail]>
>> ---
>>  hw/display/xlnx_dp.c | 4 ++++
>>  1 file changed, 4 insertions(+)
>> 
>> diff --git a/hw/display/xlnx_dp.c b/hw/display/xlnx_dp.c
>> index 3e5fb44e06..bdc229a51e 100644
>> --- a/hw/display/xlnx_dp.c
>> +++ b/hw/display/xlnx_dp.c
>> @@ -1264,9 +1264,13 @@ static void xlnx_dp_realize(DeviceState *dev, Error **errp)
>>      DisplaySurface *surface;
>>      struct audsettings as;
>>  
>> +    qdev_init_nofail(DEVICE(s->aux_bus->bridge));
>
> Eh??? Why not realize the bridge in aux_init_bus()?

Because then aux_init_bus() is no longer "init", but "init and realize".
Instead: "[PATCH v2 32/58] auxbus: New aux_bus_realize(), pairing with
aux_bus_init()".  Okay?

>> +
>>      qdev_init_nofail(DEVICE(s->dpcd));
>>      aux_map_slave(AUX_SLAVE(s->dpcd), 0x0000);
>>  
>> +    qdev_init_nofail(DEVICE(s->edid));
>
> This one is OK.
>
>> +
>>      s->console = graphic_console_init(dev, 0, &xlnx_dp_gfx_ops, s);
>>      surface = qemu_console_surface(s->console);
>>      xlnx_dpdma_set_host_data_location(s->dpdma, DP_GRAPHIC_DMA_CHANNEL,
>>

Philippe Mathieu-Daudé June 9, 2020, 7:42 a.m. UTC | #3

On 6/9/20 7:38 AM, Markus Armbruster wrote:
> Philippe Mathieu-Daudé <[e-mail]> writes:
> 
>> On 5/28/20 1:04 PM, Markus Armbruster wrote:
>>> xlnx_dp_init() creates these two devices, but they're never realized.
>>> Affects machine xlnx-zcu102.
>>>
>>> In theory, a device becomes real only on realize.  In practice, the
>>> transition from unreal to real is a fuzzy one.  The work to make a
>>> device real can be spread between realize methods (fine),
>>> instance_init methods (wrong), and board code wiring up the device
>>> (fine as long as it effectively happens on realize).  Depending on
>>> what exactly is done where, a device can work even when we neglect to
>>> realize it.
>>>
>>> These two appear to work.  Nevertheless, it's a clear misuse of the
>>> interface.  Even when it works today (more or less by chance), it can
>>> break tomorrow.
>>>
>>> Fix by realizing them in xlnx_dp_realize().
>>>
>>> Fixes: 58ac482a66de09a7590f705e53fc6a3fb8a055e8
>>> Cc: KONRAD Frederic <[e-mail]>
>>> Cc: Alistair Francis <[e-mail]>
>>> Cc: "Edgar E. Iglesias" <[e-mail]>
>>> Cc: Peter Maydell <[e-mail]>
>>> Cc: [e-mail]
>>> Signed-off-by: Markus Armbruster <[e-mail]>
>>> Reviewed-by: Edgar E. Iglesias <[e-mail]>
>>> Reviewed-by: Alistair Francis <[e-mail]>
>>> ---
>>>  hw/display/xlnx_dp.c | 4 ++++
>>>  1 file changed, 4 insertions(+)
>>>
>>> diff --git a/hw/display/xlnx_dp.c b/hw/display/xlnx_dp.c
>>> index 3e5fb44e06..bdc229a51e 100644
>>> --- a/hw/display/xlnx_dp.c
>>> +++ b/hw/display/xlnx_dp.c
>>> @@ -1264,9 +1264,13 @@ static void xlnx_dp_realize(DeviceState *dev, Error **errp)
>>>      DisplaySurface *surface;
>>>      struct audsettings as;
>>>  
>>> +    qdev_init_nofail(DEVICE(s->aux_bus->bridge));
>>
>> Eh??? Why not realize the bridge in aux_init_bus()?
> 
> Because then aux_init_bus() is no longer "init", but "init and realize".
> Instead: "[PATCH v2 32/58] auxbus: New aux_bus_realize(), pairing with
> aux_bus_init()".  Okay?

It would be easier to follow having aux_bus_realize() introduced first,
then used it directly here. Anyway it is reviewed so I don't have a
problem if this patch goes as it. Thanks.

> 
>>> +
>>>      qdev_init_nofail(DEVICE(s->dpcd));
>>>      aux_map_slave(AUX_SLAVE(s->dpcd), 0x0000);
>>>  
>>> +    qdev_init_nofail(DEVICE(s->edid));
>>
>> This one is OK.
>>
>>> +
>>>      s->console = graphic_console_init(dev, 0, &xlnx_dp_gfx_ops, s);
>>>      surface = qemu_console_surface(s->console);
>>>      xlnx_dpdma_set_host_data_location(s->dpdma, DP_GRAPHIC_DMA_CHANNEL,
>>>
> 
>

Markus Armbruster June 9, 2020, 9:35 a.m. UTC | #4

Philippe Mathieu-Daudé <[e-mail]> writes:

> On 6/9/20 7:38 AM, Markus Armbruster wrote:
>> Philippe Mathieu-Daudé <[e-mail]> writes:
>> 
>>> On 5/28/20 1:04 PM, Markus Armbruster wrote:
>>>> xlnx_dp_init() creates these two devices, but they're never realized.
>>>> Affects machine xlnx-zcu102.
>>>>
>>>> In theory, a device becomes real only on realize.  In practice, the
>>>> transition from unreal to real is a fuzzy one.  The work to make a
>>>> device real can be spread between realize methods (fine),
>>>> instance_init methods (wrong), and board code wiring up the device
>>>> (fine as long as it effectively happens on realize).  Depending on
>>>> what exactly is done where, a device can work even when we neglect to
>>>> realize it.
>>>>
>>>> These two appear to work.  Nevertheless, it's a clear misuse of the
>>>> interface.  Even when it works today (more or less by chance), it can
>>>> break tomorrow.
>>>>
>>>> Fix by realizing them in xlnx_dp_realize().
>>>>
>>>> Fixes: 58ac482a66de09a7590f705e53fc6a3fb8a055e8
>>>> Cc: KONRAD Frederic <[e-mail]>
>>>> Cc: Alistair Francis <[e-mail]>
>>>> Cc: "Edgar E. Iglesias" <[e-mail]>
>>>> Cc: Peter Maydell <[e-mail]>
>>>> Cc: [e-mail]
>>>> Signed-off-by: Markus Armbruster <[e-mail]>
>>>> Reviewed-by: Edgar E. Iglesias <[e-mail]>
>>>> Reviewed-by: Alistair Francis <[e-mail]>
>>>> ---
>>>>  hw/display/xlnx_dp.c | 4 ++++
>>>>  1 file changed, 4 insertions(+)
>>>>
>>>> diff --git a/hw/display/xlnx_dp.c b/hw/display/xlnx_dp.c
>>>> index 3e5fb44e06..bdc229a51e 100644
>>>> --- a/hw/display/xlnx_dp.c
>>>> +++ b/hw/display/xlnx_dp.c
>>>> @@ -1264,9 +1264,13 @@ static void xlnx_dp_realize(DeviceState *dev, Error **errp)
>>>>      DisplaySurface *surface;
>>>>      struct audsettings as;
>>>>  
>>>> +    qdev_init_nofail(DEVICE(s->aux_bus->bridge));
>>>
>>> Eh??? Why not realize the bridge in aux_init_bus()?
>> 
>> Because then aux_init_bus() is no longer "init", but "init and realize".
>> Instead: "[PATCH v2 32/58] auxbus: New aux_bus_realize(), pairing with
>> aux_bus_init()".  Okay?
>
> It would be easier to follow having aux_bus_realize() introduced first,

Point taken.

> then used it directly here. Anyway it is reviewed so I don't have a
> problem if this patch goes as it. Thanks.

Appreciated!

[...]

Patch

diff --git a/hw/display/xlnx_dp.c b/hw/display/xlnx_dp.c
index 3e5fb44e06..bdc229a51e 100644
--- a/hw/display/xlnx_dp.c
+++ b/hw/display/xlnx_dp.c
@@ -1264,9 +1264,13 @@  static void xlnx_dp_realize(DeviceState *dev, Error **errp)
     DisplaySurface *surface;
     struct audsettings as;
 
+    qdev_init_nofail(DEVICE(s->aux_bus->bridge));
+
     qdev_init_nofail(DEVICE(s->dpcd));
     aux_map_slave(AUX_SLAVE(s->dpcd), 0x0000);
 
+    qdev_init_nofail(DEVICE(s->edid));
+
     s->console = graphic_console_init(dev, 0, &xlnx_dp_gfx_ops, s);
     surface = qemu_console_surface(s->console);
     xlnx_dpdma_set_host_data_location(s->dpdma, DP_GRAPHIC_DMA_CHANNEL,