Hi
Am 15.01.20 um 15:37 schrieb Ville Syrjälä:
> On Wed, Jan 15, 2020 at 01:16:33PM +0100, Thomas Zimmermann wrote:
>> VBLANK interrupts can be disabled immediately or with a delay, where the
>> latter is the default. The former option can be selected by setting
>> get_vblank_timestamp, and enabling vblank_disable_immediate in struct
>> drm_device.
>>
>> The setup is only evaluated once when DRM initializes VBLANKs. Evaluating
>> the settings on each use of vblank_disable_immediate will allow for easy
>> integration of CRTC VBLANK functions.
>>
>> Signed-off-by: Thomas Zimmermann <tzimmerm...@suse.de>
>> ---
>> drivers/gpu/drm/drm_vblank.c | 31 ++++++++++++++-----------------
>> 1 file changed, 14 insertions(+), 17 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
>> index 3f1dd54cc8bb..abb085c67d82 100644
>> --- a/drivers/gpu/drm/drm_vblank.c
>> +++ b/drivers/gpu/drm/drm_vblank.c
>> @@ -481,19 +481,6 @@ int drm_vblank_init(struct drm_device *dev, unsigned
>> int num_crtcs)
>>
>> DRM_INFO("Supports vblank timestamp caching Rev 2 (21.10.2013).\n");
>>
>> - /* Driver specific high-precision vblank timestamping supported? */
>> - if (dev->driver->get_vblank_timestamp)
>> - DRM_INFO("Driver supports precise vblank timestamp query.\n");
>> - else
>> - DRM_INFO("No driver support for vblank timestamp query.\n");
>> -
>> - /* Must have precise timestamping for reliable vblank instant disable */
>> - if (dev->vblank_disable_immediate &&
>> !dev->driver->get_vblank_timestamp) {
>> - dev->vblank_disable_immediate = false;
>> - DRM_INFO("Setting vblank_disable_immediate to false because "
>> - "get_vblank_timestamp == NULL\n");
>> - }
>
> Which drivers are so broken they set vblank_disable_immediate to true
> without having the vfunc specified? IMO this code should just go away
> (or converted to a WARN).
It's probably not a problem in practice. I'll put WARN_ON around the
condition.
Best regards
Thomas
>
>> -
>> return 0;
>>
>> err:
>> @@ -1070,6 +1057,15 @@ int drm_crtc_vblank_get(struct drm_crtc *crtc)
>> }
>> EXPORT_SYMBOL(drm_crtc_vblank_get);
>>
>> +static bool __vblank_disable_immediate(struct drm_device *dev, unsigned int
>> pipe)
>> +{
>> + if (!dev->vblank_disable_immediate)
>> + return false;
>> + if (!dev->driver->get_vblank_timestamp)
>> + return false;
>> + return true;
>> +}
>> +
>> static void drm_vblank_put(struct drm_device *dev, unsigned int pipe)
>> {
>> struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
>> @@ -1086,7 +1082,7 @@ static void drm_vblank_put(struct drm_device *dev,
>> unsigned int pipe)
>> return;
>> else if (drm_vblank_offdelay < 0)
>> vblank_disable_fn(&vblank->disable_timer);
>> - else if (!dev->vblank_disable_immediate)
>> + else if (__vblank_disable_immediate(dev, pipe))
>> mod_timer(&vblank->disable_timer,
>> jiffies + ((drm_vblank_offdelay * HZ)/1000));
>> }
>> @@ -1663,7 +1659,7 @@ int drm_wait_vblank_ioctl(struct drm_device *dev, void
>> *data,
>> /* If the counter is currently enabled and accurate, short-circuit
>> * queries to return the cached timestamp of the last vblank.
>> */
>> - if (dev->vblank_disable_immediate &&
>> + if (__vblank_disable_immediate(dev, pipe) &&
>> drm_wait_vblank_is_query(vblwait) &&
>> READ_ONCE(vblank->enabled)) {
>> drm_wait_vblank_reply(dev, pipe, &vblwait->reply);
>> @@ -1820,7 +1816,7 @@ bool drm_handle_vblank(struct drm_device *dev,
>> unsigned int pipe)
>> * been signaled. The disable has to be last (after
>> * drm_handle_vblank_events) so that the timestamp is always accurate.
>> */
>> - disable_irq = (dev->vblank_disable_immediate &&
>> + disable_irq = (__vblank_disable_immediate(dev, pipe) &&
>> drm_vblank_offdelay > 0 &&
>> !atomic_read(&vblank->refcount));
>>
>> @@ -1893,7 +1889,8 @@ int drm_crtc_get_sequence_ioctl(struct drm_device
>> *dev, void *data,
>> pipe = drm_crtc_index(crtc);
>>
>> vblank = &dev->vblank[pipe];
>> - vblank_enabled = dev->vblank_disable_immediate &&
>> READ_ONCE(vblank->enabled);
>> + vblank_enabled = __vblank_disable_immediate(dev, pipe) &&
>> + READ_ONCE(vblank->enabled);
>>
>> if (!vblank_enabled) {
>> ret = drm_crtc_vblank_get(crtc);
>> --
>> 2.24.1
>>
>> _______________________________________________
>> Intel-gfx mailing list
>> Intel-gfx@lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer
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