Re: [RFC PATCH v2 1/5] drm: add vblank hooks to struct drm_crtc_funcs

On Sun, Jan 22, 2017 at 02:09:02PM +0800, Shawn Guo wrote:

From: Shawn Guo shawn.guo@linaro.org

The vblank is mostly CRTC specific and implemented as part of CRTC driver. Let's keep the vblank hooks struct drm_driver for legacy drivers, and add corresponding hooks in struct drm_crtc_funcs. These hooks take struct drm_crtc pointer as argument, and will be called by core vblank handling code for MODESET drivers.

Signed-off-by: Shawn Guo shawn.guo@linaro.org

Looks great. Just a few tiny nits below.

Cheers, Daniel

---

drivers/gpu/drm/drm_irq.c | 53 +++++++++++++++++++++++++++++++++++++++++------ include/drm/drm_crtc.h | 34 ++++++++++++++++++++++++++++++ include/drm/drm_drv.h | 9 ++++++++ 3 files changed, 90 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c index 88c69e71102e..604a2acda9d6 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -89,6 +89,19 @@ static void store_vblank(struct drm_device *dev, unsigned int pipe, write_sequnlock(&vblank->seqlock); }

+static u32 __get_vblank_counter(struct drm_device *dev, unsigned int pipe) +{

• if (drm_core_check_feature(dev, DRIVER_MODESET)) {

• struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
  

• if (crtc->funcs->get_vblank_counter)
  

• 	return crtc->funcs->get_vblank_counter(crtc);
  

• }
• /* fallback for legacy drivers */

Bikeshed: I'd drop these comments, it's kinda obvious what's going on.

• return dev->driver->get_vblank_counter(dev, pipe);

I think a great follow-up here would be to do

if (dev->driver->get_vblank_counter) return dev->driver->get_vblank_counter(dev, pipe); return drm_vblank_no_hw_counter(dev,pipe);

here (i.e. making get_vblank_counter optional), and then removing drm_vblank_no_hw_counter from all drivers. We might even want to unexport it, and adjust the help-text to state that hw without a vblank counter should leave this hook as NULL.

+}

/*

• Reset the stored timestamp for the current vblank count to correspond
• to the last vblank occurred.

@@ -112,9 +125,9 @@ static void drm_reset_vblank_timestamp(struct drm_device *dev, unsigned int pipe * when drm_vblank_enable() applies the diff */ do {

• cur_vblank = dev->driver->get_vblank_counter(dev, pipe);
  

• cur_vblank = __get_vblank_counter(dev, pipe);
  

  rc = drm_get_last_vbltimestamp(dev, pipe, &t_vblank, 0);

• } while (cur_vblank != dev->driver->get_vblank_counter(dev, pipe) && --count > 0);

• } while (cur_vblank != __get_vblank_counter(dev, pipe) && --count > 0);

  /*

  • Only reinitialize corresponding vblank timestamp if high-precision query

@@ -168,9 +181,9 @@ static void drm_update_vblank_count(struct drm_device *dev, unsigned int pipe, * corresponding vblank timestamp. */ do {

• cur_vblank = dev->driver->get_vblank_counter(dev, pipe);
  

• cur_vblank = __get_vblank_counter(dev, pipe);
  

  rc = drm_get_last_vbltimestamp(dev, pipe, &t_vblank, flags);

• } while (cur_vblank != dev->driver->get_vblank_counter(dev, pipe) && --count > 0);

• } while (cur_vblank != __get_vblank_counter(dev, pipe) && --count > 0);

  if (dev->max_vblank_count != 0) { /* trust the hw counter when it's around */

@@ -275,6 +288,21 @@ u32 drm_accurate_vblank_count(struct drm_crtc *crtc) } EXPORT_SYMBOL(drm_accurate_vblank_count);

+static void __disable_vblank(struct drm_device *dev, unsigned int pipe) +{

• if (drm_core_check_feature(dev, DRIVER_MODESET)) {

• struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
  

• if (crtc->funcs->disable_vblank) {
  

• 	crtc->funcs->disable_vblank(crtc);
  

• 	return;
  

• }
  

• }
• /* fallback for legacy drivers */
• dev->driver->disable_vblank(dev, pipe);

+}

/*

• Disable vblank irq's on crtc, make sure that last vblank count
• of hardware and corresponding consistent software vblank counter

@@ -298,7 +326,7 @@ static void vblank_disable_and_save(struct drm_device *dev, unsigned int pipe) * hardware potentially runtime suspended. */ if (vblank->enabled) {

• dev->driver->disable_vblank(dev, pipe);
  

• __disable_vblank(dev, pipe);
  

  vblank->enabled = false; }

@@ -1054,6 +1082,19 @@ void drm_crtc_send_vblank_event(struct drm_crtc *crtc, } EXPORT_SYMBOL(drm_crtc_send_vblank_event);

+static int __enable_vblank(struct drm_device *dev, unsigned int pipe) +{

• if (drm_core_check_feature(dev, DRIVER_MODESET)) {

• struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
  

• if (crtc->funcs->enable_vblank)
  

• 	return crtc->funcs->enable_vblank(crtc);
  

• }
• /* fallback for legacy drivers */
• return dev->driver->enable_vblank(dev, pipe);

+}

/**

• drm_vblank_enable - enable the vblank interrupt on a CRTC
• @dev: DRM device

@@ -1079,7 +1120,7 @@ static int drm_vblank_enable(struct drm_device *dev, unsigned int pipe) * timestamps. Filtercode in drm_handle_vblank() will * prevent double-accounting of same vblank interval. */

• ret = dev->driver->enable_vblank(dev, pipe);
  

• ret = __enable_vblank(dev, pipe);
  

  DRM_DEBUG("enabling vblank on crtc %u, ret: %d\n", pipe, ret); if (ret) atomic_dec(&vblank->refcount);

diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h index 06c943d1e04c..8b2f7266eada 100644 --- a/include/drm/drm_crtc.h +++ b/include/drm/drm_crtc.h @@ -600,6 +600,40 @@ struct drm_crtc_funcs { */ void (*atomic_print_state)(struct drm_printer *p, const struct drm_crtc_state *state);

• /**

• * @get_vblank_counter:
  

• *
  

• * Driver callback for fetching a raw hardware vblank counter for the
  

• * CRTC. It's meant to be used by new drivers as the replacement of
  

• * &drm_driver.get_vblank_counter hook.
  

Compared to the kerneldoc in drm_drv.h it misses the paragraph about wrap-around handling. Also this is missing the note about what to do if you don't have a vblank counter, but I think making the hook optional like I suggested above would be even better. If you do decided to make the hook optional, then please state that in the kernel-doc here too.

• *
  

• * Returns:
  

• *
  

• * Raw vblank counter value.
  

• */
  

• u32 (*get_vblank_counter)(struct drm_crtc *crtc);
• /**

• * @enable_vblank:
  

• *
  

• * Enable vblank interrupts for the CRTC. It's meant to be used by
  

• * new drivers as the replacement of &drm_driver.enable_vblank hook.
  

• *
  

• * Returns:
  

• *
  

• * Zero on success, appropriate errno if the vblank interrupt cannot
  

• * be enabled.
  

• */
  

• int (*enable_vblank)(struct drm_crtc *crtc);
• /**

• * @disable_vblank:
  

• *
  

• * Disable vblank interrupts for the CRTC. It's meant to be used by
  

• * new drivers as the replacement of &drm_driver.disable_vblank hook.
  

• */
  

• void (*disable_vblank)(struct drm_crtc *crtc);

};

/** diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h index 34ece393c639..6c325baddc40 100644 --- a/include/drm/drm_drv.h +++ b/include/drm/drm_drv.h @@ -123,6 +123,9 @@ struct drm_driver { * drm_crtc_vblank_off() and drm_crtc_vblank_on() when disabling or * enabling a CRTC. *

• * This is deprecated and should not be used by new drivers.
  

• * Use &drm_crtc_funcs.get_vblank_counter instead.
  

• *
  

  • Returns:
  • Raw vblank counter value.

@@ -135,6 +138,9 @@ struct drm_driver { * Enable vblank interrupts for the CRTC specified with the pipe * argument. *

• * This is deprecated and should not be used by new drivers.
  

• * Use &drm_crtc_funcs.enable_vblank instead.
  

• *
  

  • Returns:
  • Zero on success, appropriate errno if the given @crtc's vblank

@@ -147,6 +153,9 @@ struct drm_driver { * * Disable vblank interrupts for the CRTC specified with the pipe * argument.

• *
  

• * This is deprecated and should not be used by new drivers.
  

• * Use &drm_crtc_funcs.disable_vblank instead.
  

  */ void (*disable_vblank) (struct drm_device *dev, unsigned int pipe);

-- 1.9.1