Op 02-02-18 om 15:46 schreef Ville Syrjälä:
> 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>
Yeah, changed it and pushed, thanks for the suggestion. :)
> 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.
It could, but it would use 100% of cpu on older kernels that don't support poll(), if that's not a problem we could do it. :)
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