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Re: [PATCH v4 4/8] hw/misc/pca9552: Add a 'description' property for deb
From: |
Philippe Mathieu-Daudé |
Subject: |
Re: [PATCH v4 4/8] hw/misc/pca9552: Add a 'description' property for debugging purpose |
Date: |
Thu, 25 Jun 2020 10:12:34 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 |
On 6/25/20 8:37 AM, Markus Armbruster wrote:
> Cédric Le Goater <clg@kaod.org> writes:
>
>> On 6/22/20 10:31 AM, Philippe Mathieu-Daudé wrote:
>>> On 6/22/20 8:27 AM, Cédric Le Goater wrote:
>>>> On 6/21/20 12:58 AM, Philippe Mathieu-Daudé wrote:
>>>>> Add a description field to distinguish between multiple devices.
>
> Pardon my lack of imagination: how does this help you with debugging?
Ah, the patch subject is indeed incorrect, this should be:
"... for *tracing* purpose" (I use tracing when debugging).
In the next patch, we use the 'description' property:
+# pca9552.c
+pca9552_gpio_status(const char *description, const char *buf) "%s GPIOs
0-15 [%s]"
So when the machine has multiple PCA9552 and guest accesses both,
we can distinct which one is used. For me having "pca1" / "pca0"
is easier to follow than the address of the QOM object.
>
>>>> Reviewed-by: Cédric Le Goater <clg@kaod.org>
>>>>
>>>> Could it be a QOM attribute ?
>>>
>>> What do you call a 'QOM attribute'?
>>> Is it what qdev properties implement?
>>> (in this case via DEFINE_PROP_STRING).
>>
>> I meant a default Object property, which would apply to all Objects.
>
> Good point. Many devices have multiple component objects of the same
> type.
>
>> What you did is fine, so :
>>
>> Reviewed-by: Cédric Le Goater <clg@kaod.org>
>>
>> but, may be, a well defined child name is enough for the purpose.
>
> object_get_canonical_path() returns a distinct path for each (component)
> object. The path components are the child property names.
>
> Properties can have descriptions: object_property_set_description().
TIL object_property_set_description :>
Ah, there is no equivalent object_property_get_description(),
we have to use object_get_canonical_path(). Hmm, not obvious.
>
> Sufficient?
I don't know... This seems a complex way to do something simple...
This is already a QDEV. Having to use QOM API seems going
backward, since we have the DEFINE_PROP_STRING() macros available
in "hw/qdev-properties.h".
Maybe I'm not seeing the advantages clearly. I'll try later.
Thanks for your review,
Phil.
- Re: [PATCH v4 2/8] hw/misc/pca9552: Replace magic value by PCA9552_PIN_COUNT definition, (continued)
- [PATCH v4 4/8] hw/misc/pca9552: Add a 'description' property for debugging purpose, Philippe Mathieu-Daudé, 2020/06/20
- Re: [PATCH v4 4/8] hw/misc/pca9552: Add a 'description' property for debugging purpose, Cédric Le Goater, 2020/06/22
- Re: [PATCH v4 4/8] hw/misc/pca9552: Add a 'description' property for debugging purpose, Philippe Mathieu-Daudé, 2020/06/22
- Re: [PATCH v4 4/8] hw/misc/pca9552: Add a 'description' property for debugging purpose, Cédric Le Goater, 2020/06/22
- Re: [PATCH v4 4/8] hw/misc/pca9552: Add a 'description' property for debugging purpose, Markus Armbruster, 2020/06/25
- Re: [PATCH v4 4/8] hw/misc/pca9552: Add a 'description' property for debugging purpose,
Philippe Mathieu-Daudé <=
- Re: [PATCH v4 4/8] hw/misc/pca9552: Add a 'description' property for debugging purpose, Philippe Mathieu-Daudé, 2020/06/25
- Re: [PATCH v4 4/8] hw/misc/pca9552: Add a 'description' property for debugging purpose, Markus Armbruster, 2020/06/26
- Re: [PATCH v4 4/8] hw/misc/pca9552: Add a 'description' property for debugging purpose, Philippe Mathieu-Daudé, 2020/06/26
- Re: [PATCH v4 4/8] hw/misc/pca9552: Add a 'description' property for debugging purpose, Markus Armbruster, 2020/06/27
[PATCH v4 5/8] hw/misc/pca9552: Trace GPIO High/Low events, Philippe Mathieu-Daudé, 2020/06/20
[PATCH v4 6/8] hw/arm/aspeed: Describe each PCA9552 device, Philippe Mathieu-Daudé, 2020/06/20