Re: [PATCH] intel: Add support for server managed fds

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

Hi,

On 03/07/2014 02:18 PM, Chris Wilson wrote:
> On Fri, Mar 07, 2014 at 02:13:38PM +0100, Hans de Goede wrote:
>> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
>> ---
>>  src/intel_device.c | 19 ++++++-------------
>>  src/intel_module.c |  4 ++++
>>  2 files changed, 10 insertions(+), 13 deletions(-)
>>
>> diff --git a/src/intel_device.c b/src/intel_device.c
>> index d0c8092..b19884c 100644
>> --- a/src/intel_device.c
>> +++ b/src/intel_device.c
>> @@ -240,19 +240,10 @@ static char *get_path(struct xf86_platform_device *dev)
>>  #endif
>>  
>>  
>> -#if defined(ODEV_ATTRIB_FD) && 0
>> +#if defined(ODEV_ATTRIB_FD)
>>  static int get_fd(struct xf86_platform_device *dev)
>>  {
>> -	const char *str;
>> -
>> -	if (dev == NULL)
>> -		return -1;
>> -
>> -	str = xf86_get_platform_device_attrib(dev, ODEV_ATTRIB_FD);
>> -	if (str == NULL)
>> -		return -1;
>> -
>> -	return atoi(str);
>> +	return xf86_get_platform_device_int_attrib(dev, ODEV_ATTRIB_FD, -1);
>>  }
>>  
>>  #else
>> @@ -270,7 +261,7 @@ int intel_open_device(int entity_num,
>>  {
>>  	struct intel_device *dev;
>>  	char *local_path;
>> -	int fd;
>> +	int fd, init_master_count = 0;
>>  
>>  	if (intel_device_key == -1)
>>  		intel_device_key = xf86AllocateEntityPrivateIndex();
>> @@ -286,6 +277,8 @@ int intel_open_device(int entity_num,
>>  	fd = get_fd(platform);
>>  	if (fd == -1)
>>  		fd = __intel_open_device(pci, &local_path);
>> +	else
>> +		init_master_count = 1; /* Server fd is already master */
> 
> If we set master_count to non-zero, we won't ever call drmDropMaster
> (since our get/put will be unbalanced). Does the server manage
> DRM_MASTER across VT switches for this fd?

Yes (*), so the never calling drmDropMaster is the intention.

Regards,

Hans

*) Well actually this is done by systemd-logind since it requires root
rights, but from the driver POV the server takes care of it. If we IE
get server managed fds on one of the BSD-s, it will no longer be done
by systemd-logind of course, but all that driver really needs to know
is that the server takes care of this one way or the other.