Re: [RFC PATCH v1 1/2] drm/rockchip: add a notify event about vblank enable/disable

[Daniel Vetter]

On Tue, May 31, 2016 at 09:39:19PM +0800, Yakir Yang wrote:
> EDP PSR function is interesting in vblank enable or disable event,
> so it would be great introduce a way to notify encoder about this
> event.
> 
> Signed-off-by: Yakir Yang <ykk@xxxxxxxxxxxxxx>

notifiers considered evil, especially if you add a global notifier for
something that's very specific to a given crtc.

I think the better fix would be add a suitable hook to drm_bridge to allow
encoders to go into self refresh, and to wake them up from self-refresh
again.
-Daniel

> ---
>  drivers/gpu/drm/rockchip/Makefile              |  2 +-
>  drivers/gpu/drm/rockchip/rockchip_drm_notify.c | 66 ++++++++++++++++++++++++++
>  drivers/gpu/drm/rockchip/rockchip_drm_notify.h | 29 +++++++++++
>  drivers/gpu/drm/rockchip/rockchip_drm_vop.c    |  5 ++
>  4 files changed, 101 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/gpu/drm/rockchip/rockchip_drm_notify.c
>  create mode 100644 drivers/gpu/drm/rockchip/rockchip_drm_notify.h
> 
> diff --git a/drivers/gpu/drm/rockchip/Makefile b/drivers/gpu/drm/rockchip/Makefile
> index 05d0713..49fee8c 100644
> --- a/drivers/gpu/drm/rockchip/Makefile
> +++ b/drivers/gpu/drm/rockchip/Makefile
> @@ -3,7 +3,7 @@
>  # Direct Rendering Infrastructure (DRI) in XFree86 4.1.0 and higher.
>  
>  rockchipdrm-y := rockchip_drm_drv.o rockchip_drm_fb.o \
> -		rockchip_drm_gem.o rockchip_drm_vop.o
> +		rockchip_drm_gem.o rockchip_drm_vop.o rockchip_drm_notify.o
>  rockchipdrm-$(CONFIG_DRM_FBDEV_EMULATION) += rockchip_drm_fbdev.o
>  
>  obj-$(CONFIG_ROCKCHIP_ANALOGIX_DP) += analogix_dp-rockchip.o
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_notify.c b/drivers/gpu/drm/rockchip/rockchip_drm_notify.c
> new file mode 100644
> index 0000000..84111d9
> --- /dev/null
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_notify.c
> @@ -0,0 +1,66 @@
> +#include "rockchip_drm_notify.h"
> +
> +static RAW_NOTIFIER_HEAD(vblank_chain);
> +static DEFINE_MUTEX(vblank_lock);
> +
> +/**
> + * rockchip_drm_vblank_enable - Send Vblank enable event. Will only enable send
> + * Vblank if there are 1 or fewer notifiers.
> + */
> +void rockchip_drm_vblank_enable(void)
> +{
> +	mutex_lock(&vblank_lock);
> +	raw_notifier_call_chain(&vblank_chain, VBLANK_ENABLE, NULL);
> +	mutex_unlock(&vblank_lock);
> +}
> +EXPORT_SYMBOL_GPL(rockchip_drm_vblank_enable);
> +
> +/**
> + * rockchip_drm_vblank_disable - Send VBlank disable event.
> + */
> +void rockchip_drm_vblank_disable(void)
> +{
> +	mutex_lock(&vblank_lock);
> +	raw_notifier_call_chain(&vblank_chain, VBLANK_DISABLE, NULL);
> +	mutex_unlock(&vblank_lock);
> +}
> +EXPORT_SYMBOL_GPL(rockchip_drm_vblank_disable);
> +
> +/**
> + * rockchip_drm_vblank_register_notifier - Add notifier to Vblank notifiers.
> + *
> + * Enable notifiers are called when we enable/disable vblank. This can be done
> + * through rockchip_drm_vblank_enable/disable or when there is more than one
> + * sync notifier. Must call rockchip_drm_vblank_lock before calling this.
> + * @nb The notifier to add
> + */
> +int rockchip_drm_vblank_register_notifier(struct notifier_block *nb)
> +{
> +	int ret = 0;
> +
> +	if (!nb)
> +		return -EINVAL;
> +
> +	ret = raw_notifier_chain_register(&vblank_chain, nb);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(rockchip_drm_vblank_register_notifier);
> +
> +/**
> + * rockchip_drm_vblank_unregister_notifier - Remove notifier from Vblank
> + * notifiers.
> + *
> + * Must call rockchip_drm_vblank_lock before calling this.
> + * @nb The notifier to remove.
> + */
> +int rockchip_drm_vblank_unregister_notifier(struct notifier_block *nb)
> +{
> +	int ret = 0;
> +
> +	if (!nb)
> +		return -EINVAL;
> +
> +	ret = raw_notifier_chain_unregister(&vblank_chain, nb);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(rockchip_drm_vblank_unregister_notifier);
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_notify.h b/drivers/gpu/drm/rockchip/rockchip_drm_notify.h
> new file mode 100644
> index 0000000..2f28afa
> --- /dev/null
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_notify.h
> @@ -0,0 +1,29 @@
> +/*
> + * Copyright (C) 2014 Google, Inc.
> + *
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#ifndef __ROCKCHIP_DRM_NOTIFY_H
> +#define __ROCKCHIP_DRM_NOTIFY_H
> +
> +#include <linux/notifier.h>
> +
> +enum vblank_enable_op {
> +	VBLANK_ENABLE = 0,
> +	VBLANK_DISABLE,
> +};
> +
> +void rockchip_drm_vblank_enable(void);
> +void rockchip_drm_vblank_disable(void);
> +int rockchip_drm_vblank_register_notifier(struct notifier_block *nb);
> +int rockchip_drm_vblank_unregister_notifier(struct notifier_block *nb);
> +
> +#endif /* __ROCKCHIP_DRM_NOTIFY_H */
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> index 257501f..fb6ce4b 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> @@ -35,6 +35,7 @@
>  #include "rockchip_drm_gem.h"
>  #include "rockchip_drm_fb.h"
>  #include "rockchip_drm_vop.h"
> +#include "rockchip_drm_notify.h"
>  
>  #define __REG_SET_RELAXED(x, off, mask, shift, v, write_mask) \
>  		vop_mask_write(x, off, mask, shift, v, write_mask, true)
> @@ -851,6 +852,8 @@ static int vop_crtc_enable_vblank(struct drm_crtc *crtc)
>  
>  	spin_unlock_irqrestore(&vop->irq_lock, flags);
>  
> +	rockchip_drm_vblank_enable();
> +
>  	return 0;
>  }
>  
> @@ -867,6 +870,8 @@ static void vop_crtc_disable_vblank(struct drm_crtc *crtc)
>  	VOP_INTR_SET_TYPE(vop, enable, FS_INTR, 0);
>  
>  	spin_unlock_irqrestore(&vop->irq_lock, flags);
> +
> +	rockchip_drm_vblank_disable();
>  }
>  
>  static void vop_crtc_wait_for_update(struct drm_crtc *crtc)
> -- 
> 1.9.1
> 
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch