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SubjectRe: [PATCH v2] media: cec-adap: add debounce support when setting an invalid phys addr
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Hi Jonas,

On 10/1/19 10:52 PM, Jonas Karlman wrote:
> When EDID is refreshed, HDMI cable is unplugged/replugged or
> an AVR is power cycled the CEC phys addr gets invalidated.
>
> This can cause some disruption of CEC communication when
> adapter is being reconfigured.
>
> Add a debounce module option that can be used to debounce setting
> an invalid phys addr. Default is not to use debouncing.
>
> Using a configured debounce of e.g. 5000 ms, cec reconfiguring
> could be avoided when AVR was power cycled on my setup.
>
> Power off AVR (default cec.debounce=0):
> [ 101.536866] cec-dw_hdmi: new physical address f.f.f.f
> [ 102.495686] cec-dw_hdmi: new physical address 2.1.0.0
> [ 102.495913] cec-dw_hdmi: physical address: 2.1.0.0, claim 1 logical addresses
> [ 102.628574] cec-dw_hdmi: config: la 1 pa 2.1.0.0
> [ 105.130115] cec-dw_hdmi: new physical address f.f.f.f
> [ 106.979705] cec-dw_hdmi: new physical address 2.1.0.0
> [ 106.979872] cec-dw_hdmi: physical address: 2.1.0.0, claim 1 logical addresses
> [ 107.112399] cec-dw_hdmi: config: la 1 pa 2.1.0.0
> [ 108.979408] cec-dw_hdmi: reported physical address 2.0.0.0 for logical address 5
> [ 109.205386] cec-dw_hdmi: reported physical address 2.0.0.0 for logical address 11
>
> Power on AVR (default cec.debounce=0):
> [ 158.398447] cec-dw_hdmi: new physical address f.f.f.f
> [ 161.977714] cec-dw_hdmi: new physical address 2.1.0.0
> [ 161.978766] cec-dw_hdmi: physical address: 2.1.0.0, claim 1 logical addresses
> [ 162.115624] cec-dw_hdmi: config: la 1 pa 2.1.0.0
> [ 162.402750] cec-dw_hdmi: new physical address f.f.f.f
> [ 162.403389] cec-dw_hdmi: cec_transmit_msg_fh: adapter is unconfigured
> [ 162.886757] cec-dw_hdmi: new physical address 2.1.0.0
> [ 162.886964] cec-dw_hdmi: physical address: 2.1.0.0, claim 1 logical addresses
> [ 163.510725] cec-dw_hdmi: config: la 1 pa 2.1.0.0
> [ 173.034200] cec-dw_hdmi: message 10 89 02 05 timed out
>
> Power off AVR (cec.debounce=5000):
> [ 251.720471] cec-dw_hdmi: reported physical address 2.0.0.0 for logical address 5
> [ 251.922432] cec-dw_hdmi: reported physical address 2.0.0.0 for logical address 11
>
> Power on AVR (cec.debounce=5000):
> [ 291.154262] cec-dw_hdmi: reported physical address 2.0.0.0 for logical address 5
> [ 291.296199] cec-dw_hdmi: reported physical address 2.0.0.0 for logical address 11
>
> Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
> ---
> drivers/media/cec/cec-adap.c | 9 ++++++++-
> drivers/media/cec/cec-core.c | 18 ++++++++++++++++++
> drivers/media/cec/cec-priv.h | 1 +
> include/media/cec.h | 2 ++
> 4 files changed, 29 insertions(+), 1 deletion(-)

This patch looks pretty good. It's surprisingly little code for a feature like this,
nice!

This module option should be documented in Documentation/media/uapi/cec/cec-intro.rst.
Make a section "1.1 Debouncing" that explains this module option.

I also have one code comment:

>
> diff --git a/drivers/media/cec/cec-adap.c b/drivers/media/cec/cec-adap.c
> index 5ef7daeb8cbd..4c94f6da526b 100644
> --- a/drivers/media/cec/cec-adap.c
> +++ b/drivers/media/cec/cec-adap.c
> @@ -1593,8 +1593,15 @@ void cec_s_phys_addr(struct cec_adapter *adap, u16 phys_addr, bool block)
> if (IS_ERR_OR_NULL(adap))
> return;
>
> + cancel_delayed_work_sync(&adap->debounce_work);
> +
> mutex_lock(&adap->lock);
> - __cec_s_phys_addr(adap, phys_addr, block);
> + if (cec_debounce > 0 && !block && phys_addr == CEC_PHYS_ADDR_INVALID &&
> + adap->phys_addr != phys_addr)
> + schedule_delayed_work(&adap->debounce_work,
> + msecs_to_jiffies(cec_debounce));
> + else
> + __cec_s_phys_addr(adap, phys_addr, block);
> mutex_unlock(&adap->lock);
> }
> EXPORT_SYMBOL_GPL(cec_s_phys_addr);
> diff --git a/drivers/media/cec/cec-core.c b/drivers/media/cec/cec-core.c
> index 9c610e1e99b8..fa93a724d7aa 100644
> --- a/drivers/media/cec/cec-core.c
> +++ b/drivers/media/cec/cec-core.c
> @@ -28,6 +28,10 @@ static bool debug_phys_addr;
> module_param(debug_phys_addr, bool, 0644);
> MODULE_PARM_DESC(debug_phys_addr, "add CEC_CAP_PHYS_ADDR if set");
>
> +int cec_debounce;
> +module_param_named(debounce, cec_debounce, int, 0644);
> +MODULE_PARM_DESC(debounce, "debounce invalid phys addr");

This should say: "invalid physical address debounce time in ms"

I also recommend renaming 'debounce' to 'debounce_ms' to signal that this
is in ms.

Regards,

Hans

> +
> static dev_t cec_dev_t;
>
> /* Active devices */
> @@ -174,6 +178,8 @@ static void cec_devnode_unregister(struct cec_adapter *adap)
> devnode->unregistered = true;
> mutex_unlock(&devnode->lock);
>
> + cancel_delayed_work_sync(&adap->debounce_work);
> +
> mutex_lock(&adap->lock);
> __cec_s_phys_addr(adap, CEC_PHYS_ADDR_INVALID, false);
> __cec_s_log_addrs(adap, NULL, false);
> @@ -250,6 +256,17 @@ static const struct file_operations cec_error_inj_fops = {
> };
> #endif
>
> +static void cec_s_phys_addr_debounce(struct work_struct *work)
> +{
> + struct delayed_work *delayed_work = to_delayed_work(work);
> + struct cec_adapter *adap =
> + container_of(delayed_work, struct cec_adapter, debounce_work);
> +
> + mutex_lock(&adap->lock);
> + __cec_s_phys_addr(adap, CEC_PHYS_ADDR_INVALID, false);
> + mutex_unlock(&adap->lock);
> +}
> +
> struct cec_adapter *cec_allocate_adapter(const struct cec_adap_ops *ops,
> void *priv, const char *name, u32 caps,
> u8 available_las)
> @@ -293,6 +310,7 @@ struct cec_adapter *cec_allocate_adapter(const struct cec_adap_ops *ops,
> INIT_LIST_HEAD(&adap->transmit_queue);
> INIT_LIST_HEAD(&adap->wait_queue);
> init_waitqueue_head(&adap->kthread_waitq);
> + INIT_DELAYED_WORK(&adap->debounce_work, cec_s_phys_addr_debounce);
>
> /* adap->devnode initialization */
> INIT_LIST_HEAD(&adap->devnode.fhs);
> diff --git a/drivers/media/cec/cec-priv.h b/drivers/media/cec/cec-priv.h
> index 7bdf855aaecd..65176294fcf0 100644
> --- a/drivers/media/cec/cec-priv.h
> +++ b/drivers/media/cec/cec-priv.h
> @@ -27,6 +27,7 @@ static inline bool msg_is_raw(const struct cec_msg *msg)
>
> /* cec-core.c */
> extern int cec_debug;
> +extern int cec_debounce;
> int cec_get_device(struct cec_devnode *devnode);
> void cec_put_device(struct cec_devnode *devnode);
>
> diff --git a/include/media/cec.h b/include/media/cec.h
> index 4d59387bc61b..4d96ece01ba2 100644
> --- a/include/media/cec.h
> +++ b/include/media/cec.h
> @@ -195,6 +195,8 @@ struct cec_adapter {
> wait_queue_head_t kthread_waitq;
> wait_queue_head_t waitq;
>
> + struct delayed_work debounce_work;
> +
> const struct cec_adap_ops *ops;
> void *priv;
> u32 capabilities;
>

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