On Mon, Jan 02, 2017 at 01:59:10PM +0100, Tomeu Vizoso wrote:
> Don't return from the open() call on the crc/data file until the HW has
> produced a first frame, as there's great variability in when the HW is
> able to do that and userspace shouldn't have to guess when this specific
> HW is ready to start giving frame CRCs.
>
> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx>
Merged the first 2, I guess the 2 i915 patches need to wait for Dave to be
back so that we can resync the trees ...
-Daniel
> ---
>
> drivers/gpu/drm/drm_debugfs_crc.c | 23 +++++++++++++++++------
> 1 file changed, 17 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_debugfs_crc.c b/drivers/gpu/drm/drm_debugfs_crc.c
> index 68b171af237b..8b0eeeed4d78 100644
> --- a/drivers/gpu/drm/drm_debugfs_crc.c
> +++ b/drivers/gpu/drm/drm_debugfs_crc.c
> @@ -125,6 +125,12 @@ static const struct file_operations drm_crtc_crc_control_fops = {
> .write = crc_control_write
> };
>
> +static int crtc_crc_data_count(struct drm_crtc_crc *crc)
> +{
> + assert_spin_locked(&crc->lock);
> + return CIRC_CNT(crc->head, crc->tail, DRM_CRC_ENTRIES_NR);
> +}
> +
> static int crtc_crc_open(struct inode *inode, struct file *filep)
> {
> struct drm_crtc *crtc = inode->i_private;
> @@ -160,8 +166,19 @@ static int crtc_crc_open(struct inode *inode, struct file *filep)
> crc->entries = entries;
> crc->values_cnt = values_cnt;
> crc->opened = true;
> +
> + /*
> + * Only return once we got a first frame, so userspace doesn't have to
> + * guess when this particular piece of HW will be ready to start
> + * generating CRCs.
> + */
> + ret = wait_event_interruptible_lock_irq(crc->wq,
> + crtc_crc_data_count(crc),
> + crc->lock);
> spin_unlock_irq(&crc->lock);
>
> + WARN_ON(ret);
> +
> return 0;
>
> err_disable:
> @@ -189,12 +206,6 @@ static int crtc_crc_release(struct inode *inode, struct file *filep)
> return 0;
> }
>
> -static int crtc_crc_data_count(struct drm_crtc_crc *crc)
> -{
> - assert_spin_locked(&crc->lock);
> - return CIRC_CNT(crc->head, crc->tail, DRM_CRC_ENTRIES_NR);
> -}
> -
> /*
> * 1 frame field of 10 chars plus a number of CRC fields of 10 chars each, space
> * separated, with a newline at the end and null-terminated.
> --
> 2.9.3
>
> _______________________________________________
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> dri-devel@xxxxxxxxxxxxxxxxxxxxx
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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