Re: [PATCH 8/9] usb: typec: altmodes/displayport: Notify drm subsys of hotplug events

[Hans de Goede <hdegoede@redhat.com>]

Hi Heikki,

On 5/5/21 12:17 PM, Heikki Krogerus wrote:
> Hi Hans,
> 
> On Mon, May 03, 2021 at 05:46:46PM +0200, Hans de Goede wrote:
>> Use the new drm_connector_find_by_fwnode() and
>> drm_connector_oob_hotplug_event() functions to let drm/kms drivers
>> know about DisplayPort over Type-C hotplug events.
>>
>> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
>> ---
>> Changes in v2:
>> - Add missing depends on DRM to TYPEC_DP_ALTMODE Kconfig entry
>> ---
>>  drivers/usb/typec/altmodes/Kconfig       |  1 +
>>  drivers/usb/typec/altmodes/displayport.c | 40 +++++++++++++++++++++++-
>>  2 files changed, 40 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/usb/typec/altmodes/Kconfig b/drivers/usb/typec/altmodes/Kconfig
>> index 60d375e9c3c7..1a6b5e872b0d 100644
>> --- a/drivers/usb/typec/altmodes/Kconfig
>> +++ b/drivers/usb/typec/altmodes/Kconfig
>> @@ -4,6 +4,7 @@ menu "USB Type-C Alternate Mode drivers"
>>  
>>  config TYPEC_DP_ALTMODE
>>  	tristate "DisplayPort Alternate Mode driver"
>> +	depends on DRM
>>  	help
>>  	  DisplayPort USB Type-C Alternate Mode allows DisplayPort
>>  	  displays and adapters to be attached to the USB Type-C
>> diff --git a/drivers/usb/typec/altmodes/displayport.c b/drivers/usb/typec/altmodes/displayport.c
>> index aa669b9cf70e..f00dfc5c14b6 100644
>> --- a/drivers/usb/typec/altmodes/displayport.c
>> +++ b/drivers/usb/typec/altmodes/displayport.c
>> @@ -11,8 +11,10 @@
>>  #include <linux/delay.h>
>>  #include <linux/mutex.h>
>>  #include <linux/module.h>
>> +#include <linux/property.h>
>>  #include <linux/usb/pd_vdo.h>
>>  #include <linux/usb/typec_dp.h>
>> +#include <drm/drm_connector.h>
>>  #include "displayport.h"
>>  
>>  #define DP_HEADER(_dp, ver, cmd)	(VDO((_dp)->alt->svid, 1, ver, cmd)	\
>> @@ -62,12 +64,30 @@ struct dp_altmode {
>>  	struct work_struct work;
>>  	struct typec_altmode *alt;
>>  	const struct typec_altmode *port;
>> +	struct fwnode_handle *connector_fwnode;
>>  };
>>  
>> +static void dp_altmode_notify_connector(struct dp_altmode *dp)
>> +{
>> +	struct drm_connector_oob_hotplug_event_data data = { };
>> +	u8 pin_assign = DP_CONF_GET_PIN_ASSIGN(dp->data.conf);
>> +
>> +	data.connected = dp->data.status & DP_STATUS_HPD_STATE;
>> +	data.orientation = typec_altmode_get_orientation(dp->alt);
>> +
>> +	if (pin_assign & DP_PIN_ASSIGN_DP_ONLY_MASK)
>> +		data.dp_lanes = 4;
>> +	else if (pin_assign & DP_PIN_ASSIGN_MULTI_FUNC_MASK)
>> +		data.dp_lanes = 2;
>> +
>> +	drm_connector_oob_hotplug_event(dp->connector_fwnode, &data);
>> +}
>> +
>>  static int dp_altmode_notify(struct dp_altmode *dp)
>>  {
>>  	unsigned long conf;
>>  	u8 state;
>> +	int ret;
>>  
>>  	if (dp->data.conf) {
>>  		state = get_count_order(DP_CONF_GET_PIN_ASSIGN(dp->data.conf));
>> @@ -76,7 +96,12 @@ static int dp_altmode_notify(struct dp_altmode *dp)
>>  		conf = TYPEC_STATE_USB;
>>  	}
>>  
>> -	return typec_altmode_notify(dp->alt, conf, &dp->data);
>> +	ret = typec_altmode_notify(dp->alt, conf, &dp->data);
>> +	if (ret)
>> +		return ret;
>> +
>> +	dp_altmode_notify_connector(dp);
> 
> That is now going to be always called after configuration, right? The
> HPD is not necessarily issued at that point.
> 
> I think that should be called from dp_altmode_status_update(), and
> probable only if there really is HPD IRQ or HPD State changes... I
> think?

I did see this triggering a bit more often then necessary on the initial
plugin of a DP-altmode capable Type-C "dongle", so what you are suggesting
makes sense. I'll come up with a better approach for the next version.

Regards,

Hans