Re: [PATCH v2] drm/arm/malidp: Ensure that the crtcs are shutdown before removing any encoder/connector

From: Liviu Dudau
Date: Mon Apr 16 2018 - 05:45:44 EST


On Fri, Apr 13, 2018 at 04:29:48PM +0100, Ayan Kumar Halder wrote:
> One needs to ensure that the crtcs are shutdown so that the
> drm_crtc_state->connector_mask reflects that no connectors
> are currently active. Further, it reduces the reference
> count for each connector. This ensures that the connectors
> and encoders can be cleanly removed either when _unbind
> is called for the corresponding drivers or by
> drm_mode_config_cleanup().

Describing what the code does is nice and good, however it is also
useful to have a description of what the patch fixes, or why the fix
provided by the patch is better.

In this case, we need drm_atomic_helper_shutdown() to be called before
component_unbind_all() otherwise the connectors attached to the
component device will have the wrong reference count value and will not
be cleanly cleared up.

>
> Signed-off-by: Ayan Kumar Halder <ayan.halder@xxxxxxx>

With the updated commit message:

Acked-by: Liviu Dudau <liviu.dudau@xxxxxxx>

> ---
>
> Changes in v2:
> - Reset the connectors' mask and the reference counts in drm_device
> before unbinding any of its components (ie connectors and
> encoders).
>
> ---
> drivers/gpu/drm/arm/malidp_drv.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/arm/malidp_drv.c b/drivers/gpu/drm/arm/malidp_drv.c
> index 8d20faa..0a788d7 100644
> --- a/drivers/gpu/drm/arm/malidp_drv.c
> +++ b/drivers/gpu/drm/arm/malidp_drv.c
> @@ -278,7 +278,6 @@ static int malidp_init(struct drm_device *drm)
>
> static void malidp_fini(struct drm_device *drm)
> {
> - drm_atomic_helper_shutdown(drm);
> drm_mode_config_cleanup(drm);
> }
>
> @@ -646,6 +645,7 @@ static int malidp_bind(struct device *dev)
> malidp_de_irq_fini(drm);
> drm->irq_enabled = false;
> irq_init_fail:
> + drm_atomic_helper_shutdown(drm);
> component_unbind_all(dev, drm);
> bind_fail:
> of_node_put(malidp->crtc.port);
> @@ -681,6 +681,7 @@ static void malidp_unbind(struct device *dev)
> malidp_se_irq_fini(drm);
> malidp_de_irq_fini(drm);
> drm->irq_enabled = false;
> + drm_atomic_helper_shutdown(drm);
> component_unbind_all(dev, drm);
> of_node_put(malidp->crtc.port);
> malidp->crtc.port = NULL;
> --
> 2.7.4
>

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