[PATCH V2 4/4] drm/crc: add pre_crc_read function

[Rodrigo Vivi]

On Tue, Aug 21, 2018 at 02:08:58PM +0530, Mahesh Kumar wrote:
> This patch implements a callback function which will be called before
> crc read. In this function driver can implement any preparation work
> required for successfully reading CRC data.
> 
> Changes Since V1:
>  - rebase
> 
> Cc: dri-devel at lists.freedesktop.org
> Signed-off-by: Mahesh Kumar <mahesh1.kumar at intel.com>

Reviewed-by: Rodrigo Vivi <rodrigo.vivi at intel.com>

> ---
>  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 00e743153e94..e303c194c080 100644
> --- a/drivers/gpu/drm/drm_debugfs_crc.c
> +++ b/drivers/gpu/drm/drm_debugfs_crc.c
> @@ -274,6 +274,14 @@ 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 b21437bc95bf..19c2bf63935e 100644
> --- a/include/drm/drm_crtc.h
> +++ b/include/drm/drm_crtc.h
> @@ -761,6 +761,20 @@ 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);
>  	/**
>  	 * @get_crc_sources:
>  	 *
> -- 
> 2.16.2
> 
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