Re: [Intel-gfx] [PATCH v3 02/10] drm/client: Add hotplug_failed flag

[Thomas Zimmermann <tzimmermann@suse.de>]

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Hi

Am 25.01.23 um 21:57 schrieb Sam Ravnborg:
> Hi Thomas,
> 
> On Wed, Jan 25, 2023 at 09:04:07PM +0100, Thomas Zimmermann wrote:
>> Signal failed hotplugging with a flag in struct drm_client_dev. If set,
>> the client helpers will not further try to set up the fbdev display.
>>
>> This used to be signalled with a combination of cleared pointers in
>> struct drm_fb_helper,
> I failed to find where we clear the pointers. What do I miss?

Those pointer fields, dev and funcs, where allocated with kzalloc(). The 
error path in drm_fbdev_client_hotplug() later reset them to NULL again 
if an error occured.

Best regards
Thomas

> (I had assumed we would stop clearing the pointers after this change).
> 
> 	Sam
> 
> which prevents us from initializing these pointers
>> early after allocation.
>>
>> The change also harmonizes behavior among DRM clients. Additional DRM
>> clients will now handle failed hotplugging like fbdev does.
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
>> ---
>>   drivers/gpu/drm/drm_client.c        | 5 +++++
>>   drivers/gpu/drm/drm_fbdev_generic.c | 4 ----
>>   include/drm/drm_client.h            | 8 ++++++++
>>   3 files changed, 13 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_client.c b/drivers/gpu/drm/drm_client.c
>> index 09ac191c202d..009e7b10455c 100644
>> --- a/drivers/gpu/drm/drm_client.c
>> +++ b/drivers/gpu/drm/drm_client.c
>> @@ -208,8 +208,13 @@ void drm_client_dev_hotplug(struct drm_device *dev)
>>   		if (!client->funcs || !client->funcs->hotplug)
>>   			continue;
>>   
>> +		if (client->hotplug_failed)
>> +			continue;
>> +
>>   		ret = client->funcs->hotplug(client);
>>   		drm_dbg_kms(dev, "%s: ret=%d\n", client->name, ret);
>> +		if (ret)
>> +			client->hotplug_failed = true;
>>   	}
>>   	mutex_unlock(&dev->clientlist_mutex);
>>   }
>> diff --git a/drivers/gpu/drm/drm_fbdev_generic.c b/drivers/gpu/drm/drm_fbdev_generic.c
>> index 3d455a2e3fb5..135d58b8007b 100644
>> --- a/drivers/gpu/drm/drm_fbdev_generic.c
>> +++ b/drivers/gpu/drm/drm_fbdev_generic.c
>> @@ -382,10 +382,6 @@ static int drm_fbdev_client_hotplug(struct drm_client_dev *client)
>>   	struct drm_device *dev = client->dev;
>>   	int ret;
>>   
>> -	/* Setup is not retried if it has failed */
>> -	if (!fb_helper->dev && fb_helper->funcs)
>> -		return 0;
>> -
>>   	if (dev->fb_helper)
>>   		return drm_fb_helper_hotplug_event(dev->fb_helper);
>>   
>> diff --git a/include/drm/drm_client.h b/include/drm/drm_client.h
>> index 4fc8018eddda..39482527a775 100644
>> --- a/include/drm/drm_client.h
>> +++ b/include/drm/drm_client.h
>> @@ -106,6 +106,14 @@ struct drm_client_dev {
>>   	 * @modesets: CRTC configurations
>>   	 */
>>   	struct drm_mode_set *modesets;
>> +
>> +	/**
>> +	 * @hotplug failed:
>> +	 *
>> +	 * Set by client hotplug helpers if the hotplugging failed
>> +	 * before. It is usually not tried again.
>> +	 */
>> +	bool hotplug_failed;
>>   };
>>   
>>   int drm_client_init(struct drm_device *dev, struct drm_client_dev *client,
>> -- 
>> 2.39.0

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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