On 17/05/16 18:36, Daniel Vetter wrote:
> On Tue, May 17, 2016 at 7:29 PM, Jon Hunter <jonathanh@xxxxxxxxxx> wrote:
>>>> @@ -764,6 +769,9 @@ tegra_dsi_connector_duplicate_state(struct drm_connector *connector)
>>>> if (!copy)
>>>> return NULL;
>>>>
>>>> + if (copy->base.crtc)
>>>> + drm_connector_reference(connector);
>>>> +
>>>
>>> Please use __drm_atomic_helper_connector_duplicate_state instead of
>>> open-coding it.
>>
>> Unfortunately, tegra is allocating and duplicating memory for the entire
>> tegra_dsi_state structure (of which drm_connector_state is a member) in
>> this function and so I was not able to do that. However, may be Thierry
>> can comment on whether that is completely necessary and if we can move
>> to using __drm_atomic_helper_connector_duplicate_state() instead.
>
> Check out how other drivers are using this helper - it is explicitly
> for the case where you duplicate the entire struct, and it just
> initializes the core part from drm. You can then add your own fixup
> code afterwards. It also doesn't matter whether you do kmalloc or
> kcalloc or kmemdup - it does a memcpy of its own to make sure state
> gets copied.
I had a look but I don't see anyone using the
__drm_atomic_helper_connector_duplicate_state() helper, I only see that
drivers are using drm_atomic_helper_connector_duplicate_state()
directly.
Yes I understand that this helper is doing an explicit copy of the
entire drm_connector_state struct and yes I could do something like the
following ...
static struct drm_connector_state *
tegra_dsi_connector_duplicate_state(struct drm_connector *connector)
{
struct tegra_dsi_state *state = to_dsi_state(connector->state);
struct tegra_dsi_state *copy;
copy = kmemdup(state, sizeof(*state), GFP_KERNEL);
if (!copy)
return NULL;
__drm_atomic_helper_connector_duplicate_state(connector,
©->base);
return ©->base;
}
... however, this means that I am copying the drm_connector_state twice
and this is what I was trying to avoid. Sorry if I am misunderstanding
you here, but I don't see how I can avoid the 2nd copy if I use
__drm_atomic_helper_connector_duplicate_state().
Cheers
Jon
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