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SubjectRe: [PATCH v6 4/8] drm: tda998x: use cec_notifier_conn_(un)register
On Tue, Aug 13, 2019 at 01:02:36PM +0200, Dariusz Marcinkiewicz wrote:
> Use the new cec_notifier_conn_(un)register() functions to
> (un)register the notifier for the HDMI connector, and fill
> in the cec_connector_info.
>
> Changes since v2:
> - cec_notifier_phys_addr_invalidate where appropriate,
> - don't check for NULL notifier before calling
> cec_notifier_conn_unregister.
> Changes since v1:
> Add memory barrier to make sure that the notifier
> becomes visible to the irq thread once it is
> fully constructed.
>
> Signed-off-by: Dariusz Marcinkiewicz <darekm@google.com>
> Tested-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
> ---
> drivers/gpu/drm/i2c/tda998x_drv.c | 33 +++++++++++++++++++++----------
> 1 file changed, 23 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/i2c/tda998x_drv.c b/drivers/gpu/drm/i2c/tda998x_drv.c
> index 61e042918a7fc..19a63ee1b3f53 100644
> --- a/drivers/gpu/drm/i2c/tda998x_drv.c
> +++ b/drivers/gpu/drm/i2c/tda998x_drv.c
> @@ -804,9 +804,14 @@ static irqreturn_t tda998x_irq_thread(int irq, void *data)
> if (lvl & CEC_RXSHPDLEV_HPD) {
> tda998x_edid_delay_start(priv);
> } else {
> + struct cec_notifier *notify;
> +
> schedule_work(&priv->detect_work);
> - cec_notifier_set_phys_addr(priv->cec_notify,
> - CEC_PHYS_ADDR_INVALID);
> +
> + notify = READ_ONCE(priv->cec_notify);
> + if (notify)
> + cec_notifier_phys_addr_invalidate(
> + notify);
> }
>
> handled = true;
> @@ -1331,6 +1336,8 @@ static int tda998x_connector_init(struct tda998x_priv *priv,
> struct drm_device *drm)
> {
> struct drm_connector *connector = &priv->connector;
> + struct cec_connector_info conn_info;
> + struct cec_notifier *notifier;
> int ret;
>
> connector->interlace_allowed = 1;
> @@ -1347,6 +1354,19 @@ static int tda998x_connector_init(struct tda998x_priv *priv,
> if (ret)
> return ret;
>
> + cec_fill_conn_info_from_drm(&conn_info, connector);
> +
> + notifier = cec_notifier_conn_register(priv->cec_glue.parent,
> + NULL, &conn_info);
> + if (!notifier)
> + return -ENOMEM;
> + /*
> + * Make sure that tda998x_irq_thread does see the notifier
> + * when it fully constructed.
> + */
> + smp_wmb();
> + priv->cec_notify = notifier;

To nitpick, this comment and the following code do not go together.

I think what you actually mean is:

* Make sure that tda998x_irq_thread sees the notifier
* only after it is fully constructed.

> +
> drm_connector_attach_encoder(&priv->connector,
> priv->bridge.encoder);
>
> @@ -1790,8 +1810,7 @@ static void tda998x_destroy(struct device *dev)
>
> i2c_unregister_device(priv->cec);
>
> - if (priv->cec_notify)
> - cec_notifier_put(priv->cec_notify);
> + cec_notifier_conn_unregister(priv->cec_notify);

This also doesn't make sense: tda998x_destroy() is the opposite of
tda998x_create(). However, tda998x_connector_destroy() is the
opposite of tda998x_connector_create().

By moving the CEC creation code into tda998x_connector_create(), you
are creating the possibility for the following sequence to mess up
CEC and leak:

tda998x_create()
tda998x_connector_create()
tda998x_connector_destroy()
tda998x_connector_create()
tda998x_connector_destroy()
tda998x_destroy()

Anything you create in tda998x_connector_create() must be cleaned up
by tda998x_connector_destroy().

> }
>
> static int tda998x_create(struct device *dev)
> @@ -1916,12 +1935,6 @@ static int tda998x_create(struct device *dev)
> cec_write(priv, REG_CEC_RXSHPDINTENA, CEC_RXSHPDLEV_HPD);
> }
>
> - priv->cec_notify = cec_notifier_get(dev);
> - if (!priv->cec_notify) {
> - ret = -ENOMEM;
> - goto fail;
> - }
> -
> priv->cec_glue.parent = dev;
> priv->cec_glue.data = priv;
> priv->cec_glue.init = tda998x_cec_hook_init;
> --
> 2.23.0.rc1.153.gdeed80330f-goog
>
>

--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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