Re: [PATCH 02/10] drm: crc: Introduce pre_crc_read function

["Kumar, Mahesh" <mahesh1.kumar@intel.com>]

Hi,


On 6/27/2018 8:48 PM, Maarten Lankhorst wrote:
> Op 27-06-18 om 16:44 schreef Mahesh Kumar:
>> This patch implements a callback function "pre_crc_read" which will
>> be called before crc read. In this function driver can implement and
>> preparation work required for successfully reading CRC data.
>>
>> Signed-off-by: Mahesh Kumar <mahesh1.kumar@intel.com>
>> Cc: dri-devel@lists.freedesktop.org
>> ---
>>   drivers/gpu/drm/drm_debugfs_crc.c |  8 ++++++++
>>   include/drm/drm_crtc.h            | 14 ++++++++++++++
>>   2 files changed, 22 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/drm_debugfs_crc.c b/drivers/gpu/drm/drm_debugfs_crc.c
>> index c6a725b79ac6..2b4a737c5aeb 100644
>> --- a/drivers/gpu/drm/drm_debugfs_crc.c
>> +++ b/drivers/gpu/drm/drm_debugfs_crc.c
>> @@ -278,6 +278,14 @@ static ssize_t crtc_crc_read(struct file *filep, char __user *user_buf,
>>   		return 0;
>>   	}
>>   
>> +	if (crtc->funcs->pre_crc_read) {
>> +		ret = crtc->funcs->pre_crc_read(crtc);
>> +		if (ret) {
>> +			spin_unlock_irq(&crc->lock);
>> +			return ret;
>> +		}
>> +	}
>> +
>>   	/* Nothing to read? */
>>   	while (crtc_crc_data_count(crc) == 0) {
>>   		if (filep->f_flags & O_NONBLOCK) {
>> diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
>> index 1a6dcbf91744..bae432469616 100644
>> --- a/include/drm/drm_crtc.h
>> +++ b/include/drm/drm_crtc.h
>> @@ -676,6 +676,20 @@ struct drm_crtc_funcs {
>>   	 */
>>   	int (*verify_crc_source)(struct drm_crtc *crtc, const char *source,
>>   				 size_t *values_cnt);
>> +	/**
>> +	 * @pre_crc_read:
>> +	 *
>> +	 * Driver callback for performing any preparation work required by
>> +	 * driver before reading CRC
>> +	 *
>> +	 * This callback is optional if the driver does not support CRC
>> +	 * generation or no prework is required before reading the crc
>> +	 *
>> +	 * RETURNS:
>> +	 *
>> +	 * 0 on success or a negative error code on failure.
>> +	 */
>> +	int (*pre_crc_read)(struct drm_crtc *crtc);
>>   
>>   	/**
>>   	 * @atomic_print_state:
> I think this patch might have to be dropped, or reordered after the revert in 10/10, because else in theory open could block. :)
>
> Or maybe just drop until we have upstream kernel users?
thanks,
Can reorder it after patch-10 and if others also vote to drop it will 
take decision accordingly, atleast it should not block other patches :)

-Mahesh
>
> ~Maarten
>

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