Re: [PATCH v3 2/4] drm/rockchip: add an common abstracted PSR driver

[Daniel Vetter]

On Fri, Jul 01, 2016 at 02:00:00PM -0400, Sean Paul wrote:
> On Fri, Jul 1, 2016 at 5:19 AM, Yakir Yang <ykk@xxxxxxxxxxxxxx> wrote:
> > The PSR driver have exported four symbols for specific device driver:
> > - rockchip_drm_psr_register()
> > - rockchip_drm_psr_unregister()
> > - rockchip_drm_psr_enable()
> > - rockchip_drm_psr_disable()
> > - rockchip_drm_psr_flush()
> >
> > Encoder driver should call the register/unregister interfaces to hook
> > itself into common PSR driver, encoder have implement the 'psr_set'
> > callback which use the set PSR state in hardware side.
> >
> > Crtc driver would call the enable/disable interfaces when vblank is
> > enable/disable, after that the common PSR driver would call the encoder
> > registered callback to set the PSR state.
> >
> 
> This feels overly complicated. It seems like you could cut out a bunch
> of code by just coding the psr functions into vop and
> analogix_dp-rockchip. I suppose the only reason to keep it abstracted
> would be if you plan on supporting psr in a different encoder or crtc
> in rockchip, or if you're planning on moving this into drm core.

Agreed on the layers of indirection. Also, you end up with 3 delayed
timers in total:
- defio timer from fbdev emulation
- timer in this abstraction
- delayed work in the psr backend driver

I'd cut out at least the middle one.

But since this seems to correctly use the ->dirty callback it gets my Ack
either way ;-)

Cheers, Daniel

> 
> Perhaps others will disagree with this sentiment and this is the right
> thing to do.
> 
> > Fb driver would call the flush interface in 'fb->dirty' callback, this
> > helper function would force all PSR enabled encoders to exit from PSR
> > for 3 seconds.
> >
> > Signed-off-by: Yakir Yang <ykk@xxxxxxxxxxxxxx>
> > ---
> > Changes in v3:
> > - split the psr flow into an common abstracted PSR driver
> > - implement the 'fb->dirty' callback function (Daniel)
> > - avoid to use notify to acqiure for vact event (Daniel)
> > - remove psr_active() callback which introduce in v2
> >
> > Changes in v2: None
> >
> >  drivers/gpu/drm/rockchip/Makefile           |   2 +-
> >  drivers/gpu/drm/rockchip/rockchip_drm_fb.c  |  12 ++
> >  drivers/gpu/drm/rockchip/rockchip_drm_psr.c | 200 ++++++++++++++++++++++++++++
> >  drivers/gpu/drm/rockchip/rockchip_drm_psr.h |  12 ++
> >  drivers/gpu/drm/rockchip/rockchip_drm_vop.c |  24 ++++
> >  5 files changed, 249 insertions(+), 1 deletion(-)
> >  create mode 100644 drivers/gpu/drm/rockchip/rockchip_drm_psr.c
> >  create mode 100644 drivers/gpu/drm/rockchip/rockchip_drm_psr.h
> >
> > diff --git a/drivers/gpu/drm/rockchip/Makefile b/drivers/gpu/drm/rockchip/Makefile
> > index 05d0713..9746365 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_psr.o rockchip_drm_vop.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_fb.c b/drivers/gpu/drm/rockchip/rockchip_drm_fb.c
> > index 20f12bc..0fec18f 100644
> > --- a/drivers/gpu/drm/rockchip/rockchip_drm_fb.c
> > +++ b/drivers/gpu/drm/rockchip/rockchip_drm_fb.c
> > @@ -21,6 +21,7 @@
> >
> >  #include "rockchip_drm_drv.h"
> >  #include "rockchip_drm_gem.h"
> > +#include "rockchip_drm_psr.h"
> >
> >  #define to_rockchip_fb(x) container_of(x, struct rockchip_drm_fb, fb)
> >
> > @@ -66,9 +67,20 @@ static int rockchip_drm_fb_create_handle(struct drm_framebuffer *fb,
> >                                      rockchip_fb->obj[0], handle);
> >  }
> >
> > +static int rockchip_drm_fb_dirty(struct drm_framebuffer *fb,
> > +                                struct drm_file *file,
> > +                                unsigned int flags, unsigned int color,
> > +                                struct drm_clip_rect *clips,
> > +                                unsigned int num_clips)
> > +{
> > +       rockchip_drm_psr_flush();
> > +       return 0;
> > +}
> > +
> >  static const struct drm_framebuffer_funcs rockchip_drm_fb_funcs = {
> >         .destroy        = rockchip_drm_fb_destroy,
> >         .create_handle  = rockchip_drm_fb_create_handle,
> > +       .dirty          = rockchip_drm_fb_dirty,
> >  };
> >
> >  static struct rockchip_drm_fb *
> > diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_psr.c b/drivers/gpu/drm/rockchip/rockchip_drm_psr.c
> > new file mode 100644
> > index 0000000..c044443
> > --- /dev/null
> > +++ b/drivers/gpu/drm/rockchip/rockchip_drm_psr.c
> > @@ -0,0 +1,200 @@
> > +#include <drm/drm_crtc_helper.h>
> > +
> > +#include "rockchip_drm_psr.h"
> > +
> > +#define PSR_FLUSH_TIMEOUT      msecs_to_jiffies(3000) /* 3 seconds */
> > +
> > +static LIST_HEAD(psr_list);
> > +static DEFINE_MUTEX(psr_list_mutex);
> 
> I'm not crazy about these globals. Perhaps you can initialize them
> with the rockchip driver and tuck them in a driver-level struct
> (rockchip_drm_private or something).
> 
> 
> > +
> > +enum psr_state {
> > +       PSR_FLUSH,
> > +       PSR_ENABLE,
> > +       PSR_DISABLE,
> > +};
> > +
> > +struct psr_drv {
> > +       struct list_head list;
> > +       enum psr_state state;
> > +       struct mutex state_mutex;
> > +
> > +       struct timer_list flush_timer;
> > +
> > +       struct drm_encoder *encoder;
> > +       int (*set)(struct drm_encoder *encoder, bool enable);
> > +};
> > +
> > +static struct psr_drv *find_psr_by_crtc(struct drm_crtc *crtc)
> > +{
> > +       struct psr_drv *psr;
> > +
> > +       mutex_lock(&psr_list_mutex);
> > +       list_for_each_entry(psr, &psr_list, list) {
> > +               if (psr->encoder->crtc == crtc) {
> > +                       mutex_unlock(&psr_list_mutex);
> > +                       return psr;
> > +               }
> > +       }
> > +       mutex_unlock(&psr_list_mutex);
> > +
> > +       return ERR_PTR(-ENODEV);
> > +}
> > +
> > +static void psr_enable(struct psr_drv *psr)
> > +{
> > +       if (psr->state == PSR_ENABLE)
> > +               return;
> 
> Should you be worried about races by accessing this outside of the state mutex?
> 
> > +
> > +       mutex_lock(&psr->state_mutex);
> > +       psr->state = PSR_ENABLE;
> > +       psr->set(psr->encoder, true);
> > +       mutex_unlock(&psr->state_mutex);
> > +}
> > +
> > +static void psr_disable(struct psr_drv *psr)
> > +{
> > +       if (psr->state == PSR_DISABLE)
> > +               return;
> > +
> > +       mutex_lock(&psr->state_mutex);
> > +       psr->state = PSR_DISABLE;
> > +       psr->set(psr->encoder, false);
> > +       mutex_unlock(&psr->state_mutex);
> > +}
> > +
> > +static void psr_flush_handler(unsigned long data)
> > +{
> > +       struct psr_drv *psr = (struct psr_drv *)data;
> > +
> > +       if (!psr || psr->state != PSR_FLUSH)
> > +               return;
> > +
> > +       psr_enable(psr);
> > +}
> > +
> > +/**
> > + * rockchip_drm_psr_enable - enable the encoder PSR which bind to given CRTC
> > + * @crtc: CRTC to obtain the PSR encoder
> > + *
> > + * Returns:
> > + * Zero on success, negative errno on failure.
> > + */
> > +int rockchip_drm_psr_enable(struct drm_crtc *crtc)
> > +{
> > +       struct psr_drv *psr = find_psr_by_crtc(crtc);
> > +
> > +       if (IS_ERR(psr))
> > +               return PTR_ERR(psr);
> > +
> > +       psr_enable(psr);
> > +       return 0;
> > +}
> > +EXPORT_SYMBOL(rockchip_drm_psr_enable);
> > +
> > +/**
> > + * rockchip_drm_psr_disable - disable the encoder PSR which bind to given CRTC
> > + * @crtc: CRTC to obtain the PSR encoder
> > + *
> > + * Returns:
> > + * Zero on success, negative errno on failure.
> > + */
> > +int rockchip_drm_psr_disable(struct drm_crtc *crtc)
> > +{
> > +       struct psr_drv *psr = find_psr_by_crtc(crtc);
> > +
> > +       if (IS_ERR(psr))
> > +               return PTR_ERR(psr);
> > +
> > +       psr_disable(psr);
> > +       return 0;
> > +}
> > +EXPORT_SYMBOL(rockchip_drm_psr_disable);
> > +
> > +/**
> > + * rockchip_drm_psr_flush - force to flush all registered PSR encoders
> > + *
> > + * Disable the PSR function for all registered encoders, and then enable the
> > + * PSR function back after 5 second. If encoder PSR state have been changed
> 
> s/5 second/PSR_FLUSH_TIMEOUT/
> 
> > + * during flush time, then keep the state no change after flush timeout.
> > + *
> > + * Returns:
> > + * Zero on success, negative errno on failure.
> > + */
> > +void rockchip_drm_psr_flush(void)
> > +{
> > +       struct psr_drv *psr;
> > +
> > +       mutex_lock(&psr_list_mutex);
> > +       list_for_each_entry(psr, &psr_list, list) {
> > +               if (psr->state == PSR_DISABLE)
> > +                       continue;
> > +
> > +               mod_timer(&psr->flush_timer,
> > +                         round_jiffies_up(jiffies + PSR_FLUSH_TIMEOUT));
> > +
> > +               psr_disable(psr);
> > +               psr->state = PSR_FLUSH;
> 
> This is set outside of state_mutex, is that intentional?
> 
> > +       }
> > +       mutex_unlock(&psr_list_mutex);
> > +}
> > +EXPORT_SYMBOL(rockchip_drm_psr_flush);
> > +
> > +/**
> > + * rockchip_drm_psr_register - register encoder to psr driver
> > + * @encoder: encoder that obtain the PSR function
> > + * @psr_set: call back to set PSR state
> > + *
> > + * Returns:
> > + * Zero on success, negative errno on failure.
> > + */
> > +int rockchip_drm_psr_register(struct drm_encoder *encoder,
> > +                             int (*psr_set)(struct drm_encoder *, bool enable))
> > +{
> > +       struct psr_drv *psr;
> > +
> > +       if (!encoder || !psr_set)
> > +               return -EINVAL;
> > +
> > +       psr = kzalloc(sizeof(struct psr_drv), GFP_KERNEL);
> > +       if (!psr)
> > +               return -ENOMEM;
> > +
> > +       setup_timer(&psr->flush_timer, psr_flush_handler, (unsigned long)psr);
> > +
> > +       mutex_init(&psr->state_mutex);
> > +
> > +       psr->state = PSR_DISABLE;
> > +       psr->encoder = encoder;
> > +       psr->set = psr_set;
> > +
> > +       mutex_lock(&psr_list_mutex);
> > +       list_add_tail(&psr->list, &psr_list);
> > +       mutex_unlock(&psr_list_mutex);
> > +
> > +       return 0;
> > +}
> > +EXPORT_SYMBOL(rockchip_drm_psr_register);
> > +
> > +/**
> > + * rockchip_drm_psr_unregister - unregister encoder to psr driver
> > + * @encoder: encoder that obtain the PSR function
> > + * @psr_set: call back to set PSR state
> > + *
> > + * Returns:
> > + * Zero on success, negative errno on failure.
> > + */
> > +void rockchip_drm_psr_unregister(struct drm_encoder *encoder)
> > +{
> > +       struct psr_drv *psr;
> > +
> > +       mutex_lock(&psr_list_mutex);
> > +       list_for_each_entry(psr, &psr_list, list) {
> > +               if (psr->encoder == encoder) {
> > +                       del_timer(&psr->flush_timer);
> > +                       list_del(&psr->list);
> > +                       kfree(psr);
> > +               }
> > +       }
> > +       mutex_unlock(&psr_list_mutex);
> > +}
> > +EXPORT_SYMBOL(rockchip_drm_psr_unregister);
> > diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_psr.h b/drivers/gpu/drm/rockchip/rockchip_drm_psr.h
> > new file mode 100644
> > index 0000000..622f605
> > --- /dev/null
> > +++ b/drivers/gpu/drm/rockchip/rockchip_drm_psr.h
> > @@ -0,0 +1,12 @@
> > +#ifndef __ROCKCHIP_DRM_PSR___
> > +#define __ROCKCHIP_DRM_PSR___
> > +
> > +void rockchip_drm_psr_flush(void);
> > +int rockchip_drm_psr_enable(struct drm_crtc *crtc);
> > +int rockchip_drm_psr_disable(struct drm_crtc *crtc);
> > +
> > +int rockchip_drm_psr_register(struct drm_encoder *encoder,
> > +                           int (*psr_set)(struct drm_encoder *, bool enable));
> > +void rockchip_drm_psr_unregister(struct drm_encoder *encoder);
> > +
> > +#endif /* __ROCKCHIP_DRM_PSR__ */
> > diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> > index cd3cac5..3c6dfc5 100644
> > --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> > +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> > @@ -34,6 +34,7 @@
> >  #include "rockchip_drm_drv.h"
> >  #include "rockchip_drm_gem.h"
> >  #include "rockchip_drm_fb.h"
> > +#include "rockchip_drm_psr.h"
> >  #include "rockchip_drm_vop.h"
> >
> >  #define __REG_SET_RELAXED(x, off, mask, shift, v, write_mask) \
> > @@ -121,6 +122,9 @@ struct vop {
> >         /* protected by dev->event_lock */
> >         struct drm_pending_vblank_event *event;
> >
> > +       bool psr_enabled;
> > +       struct delayed_work psr_work;
> > +
> >         struct completion line_flag_completion;
> >
> >         const struct vop_data *data;
> > @@ -911,6 +915,16 @@ static const struct drm_plane_funcs vop_plane_funcs = {
> >         .atomic_destroy_state = vop_atomic_plane_destroy_state,
> >  };
> >
> > +static void vop_psr_work(struct work_struct *work)
> > +{
> > +       struct vop *vop = container_of(work, typeof(*vop), psr_work.work);
> > +
> > +       if (vop->psr_enabled)
> > +               rockchip_drm_psr_enable(&vop->crtc);
> > +       else
> > +               rockchip_drm_psr_disable(&vop->crtc);
> > +}
> > +
> >  static int vop_crtc_enable_vblank(struct drm_crtc *crtc)
> >  {
> >         struct vop *vop = to_vop(crtc);
> > @@ -925,6 +939,9 @@ static int vop_crtc_enable_vblank(struct drm_crtc *crtc)
> >
> >         spin_unlock_irqrestore(&vop->irq_lock, flags);
> >
> > +       vop->psr_enabled = false;
> > +       schedule_delayed_work(&vop->psr_work, msecs_to_jiffies(10));
> > +
> >         return 0;
> >  }
> >
> > @@ -941,6 +958,9 @@ 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);
> > +
> > +       vop->psr_enabled = true;
> > +       schedule_delayed_work(&vop->psr_work, msecs_to_jiffies(10));
> >  }
> >
> >  static void vop_crtc_wait_for_update(struct drm_crtc *crtc)
> > @@ -1582,6 +1602,10 @@ static int vop_bind(struct device *dev, struct device *master, void *data)
> >                 return ret;
> >
> >         pm_runtime_enable(&pdev->dev);
> > +
> > +       vop->psr_enabled = false;
> > +       INIT_DELAYED_WORK(&vop->psr_work, vop_psr_work);
> > +
> >         return 0;
> >  }
> >
> > --
> > 1.9.1
> >
> >

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