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

[Markus Armbruster]

Philippe Mathieu-Daudé <f4bug@amsat.org> writes:

> On 6/9/20 7:38 AM, Markus Armbruster wrote:
>> Philippe Mathieu-Daudé <f4bug@amsat.org> 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 <fred.konrad@greensocs.com>
>>>> Cc: Alistair Francis <alistair@alistair23.me>
>>>> Cc: "Edgar E. Iglesias" <edgar.iglesias@gmail.com>
>>>> Cc: Peter Maydell <peter.maydell@linaro.org>
>>>> Cc: qemu-arm@nongnu.org
>>>> Signed-off-by: Markus Armbruster <armbru@redhat.com>
>>>> Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
>>>> Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
>>>> ---
>>>>  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!

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