On Fri, Feb 02, 2018 at 03:27:43PM +0100, Maarten Lankhorst wrote:
> This will make it possible for userspace to know whether reading
> will block, without blocking on the fd. This makes it possible to
> drain all queued CRC's in blocking mode, without having to reopen
> the fd.
>
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/drm_debugfs_crc.c | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_debugfs_crc.c b/drivers/gpu/drm/drm_debugfs_crc.c
> index 9dd879589a2c..8af1a74ec64d 100644
> --- a/drivers/gpu/drm/drm_debugfs_crc.c
> +++ b/drivers/gpu/drm/drm_debugfs_crc.c
> @@ -307,10 +307,29 @@ static ssize_t crtc_crc_read(struct file *filep, char __user *user_buf,
> return LINE_LEN(crc->values_cnt);
> }
>
> +static unsigned int crtc_crc_poll(struct file *file, poll_table *wait)
> +{
> + struct drm_crtc *crtc = file->f_inode->i_private;
> + struct drm_crtc_crc *crc = &crtc->crc;
> + unsigned ret;
> +
> + poll_wait(file, &crc->wq, wait);
> +
> + spin_lock_irq(&crc->lock);
> + if (crc->source && crtc_crc_data_count(crc))
> + ret = POLLIN;
Most places seem to also set POLLRDNORM. Maybe we should do it as well?
Apart from that this seems good to me.
Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Could replace the usleep() loop in igt read_one_crc() with
poll/select() I suppose? Either that or we should switch between
blocking and nonblocking dynamically.
> + else
> + ret = 0;
> + spin_unlock_irq(&crc->lock);
> +
> + return ret;
> +}
> +
> static const struct file_operations drm_crtc_crc_data_fops = {
> .owner = THIS_MODULE,
> .open = crtc_crc_open,
> .read = crtc_crc_read,
> + .poll = crtc_crc_poll,
> .release = crtc_crc_release,
> };
>
> --
> 2.15.1
>
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--
Ville Syrjälä
Intel OTC
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