- Integrate into the drm DocBook - Disable kerneldoc for functions not exported to drivers. - Properly document the new drm_vblank_on|off and add cautious comments explaining when drm_vblank_pre|post_modesets shouldn't be used. - General polish and OCD.
v2: Polish as suggested by Thierry.
Cc: Thierry Reding thierry.reding@gmail.com Signed-off-by: Daniel Vetter daniel.vetter@ffwll.ch --- Documentation/DocBook/drm.tmpl | 5 +- drivers/gpu/drm/drm_irq.c | 165 +++++++++++++++++++++++++++++------------ 2 files changed, 121 insertions(+), 49 deletions(-)
diff --git a/Documentation/DocBook/drm.tmpl b/Documentation/DocBook/drm.tmpl index 96cee6438472..9c47e3147ad1 100644 --- a/Documentation/DocBook/drm.tmpl +++ b/Documentation/DocBook/drm.tmpl @@ -2519,6 +2519,10 @@ void (*disable_vblank) (struct drm_device *dev, int crtc);</synopsis> with a call to <function>drm_vblank_cleanup</function> in the driver <methodname>unload</methodname> operation handler. </para> + <sect2> + <title>Vertical Blanking and Interrupt Handling Functions Reference</title> +!Edrivers/gpu/drm/drm_irq.c + </sect2> </sect1>
<!-- Internals: open/close, file operations and ioctls --> @@ -2871,7 +2875,6 @@ int num_ioctls;</synopsis> </listitem> </varlistentry> </variablelist> -<!--!Edrivers/char/drm/drm_irq.c--> </para> </sect1>
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c index dd786d84daab..f3dafccca456 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -1,6 +1,5 @@ -/** - * \file drm_irq.c - * IRQ support +/* + * drm_irq.c IRQ and vblank support * * \author Rickard E. (Rik) Faith faith@valinux.com * \author Gareth Hughes gareth@valinux.com @@ -156,6 +155,12 @@ static void vblank_disable_fn(unsigned long arg) spin_unlock_irqrestore(&dev->vbl_lock, irqflags); }
+/** + * drm_vblank_cleanup - cleanup vblank support + * @dev: DRM device + * + * This function cleans up any resources allocated in drm_vblank_init. + */ void drm_vblank_cleanup(struct drm_device *dev) { int crtc; @@ -175,6 +180,16 @@ void drm_vblank_cleanup(struct drm_device *dev) } EXPORT_SYMBOL(drm_vblank_cleanup);
+/** + * drm_vblank_init - initialize vblank support + * @dev: drm_device + * @num_crtcs: number of crtcs supported by @dev + * + * This function initializes vblank support for @num_crtcs display pipelines. + * + * Returns: + * Zero on success or a negative error code on failure. + */ int drm_vblank_init(struct drm_device *dev, int num_crtcs) { int i, ret = -ENOMEM; @@ -238,13 +253,21 @@ static void drm_irq_vgaarb_nokms(void *cookie, bool state) }
/** - * Install IRQ handler. - * - * \param dev DRM device. + * drm_irq_install - install IRQ handler + * @dev: DRM device + * @irq: IRQ number to install the handler for * * Initializes the IRQ related data. Installs the handler, calling the driver - * \c irq_preinstall() and \c irq_postinstall() functions - * before and after the installation. + * irq_preinstall() and irq_postinstall() functions before and after the + * installation. + * + * This is the simplified helper interface provided for drivers with no special + * needs. Drivers which need to install interrupt handlers for multiple + * interrupts must instead set drm_device->irq_enabled to signal the DRM core + * that vblank interrupts are available. + * + * Returns: + * Zero on success or a negative error code on failure. */ int drm_irq_install(struct drm_device *dev, int irq) { @@ -304,11 +327,20 @@ int drm_irq_install(struct drm_device *dev, int irq) EXPORT_SYMBOL(drm_irq_install);
/** - * Uninstall the IRQ handler. + * drm_irq_uninstall - uninstall the IRQ handler + * @dev: DRM device + * + * Calls the driver's irq_uninstall() function and unregisters the IRQ handler. + * This should only be called by drivers which used drm_irq_install() to set up + * their interrupt handler. Other drivers must only reset + * drm_device->irq_enabled to false. * - * \param dev DRM device. + * Note that for kernel modesetting drivers it is a bug if this function fails. + * The sanity checks are only to catch buggy user modesetting drivers which call + * the same function through an ioctl. * - * Calls the driver's \c irq_uninstall() function, and stops the irq. + * Returns: + * Zero on success or a negative error code on failure. */ int drm_irq_uninstall(struct drm_device *dev) { @@ -353,7 +385,7 @@ int drm_irq_uninstall(struct drm_device *dev) } EXPORT_SYMBOL(drm_irq_uninstall);
-/** +/* * IRQ control ioctl. * * \param inode device inode. @@ -406,15 +438,14 @@ int drm_control(struct drm_device *dev, void *data, }
/** - * drm_calc_timestamping_constants - Calculate vblank timestamp constants - * - * @crtc drm_crtc whose timestamp constants should be updated. - * @mode display mode containing the scanout timings + * drm_calc_timestamping_constants - calculate vblank timestamp constants + * @crtc: drm_crtc whose timestamp constants should be updated. + * @mode: display mode containing the scanout timings * * Calculate and store various constants which are later * needed by vblank and swap-completion timestamping, e.g, * by drm_calc_vbltimestamp_from_scanoutpos(). They are - * derived from crtc's true scanout timing, so they take + * derived from CRTC's true scanout timing, so they take * things like panel scaling or other adjustments into account. */ void drm_calc_timestamping_constants(struct drm_crtc *crtc, @@ -459,11 +490,22 @@ void drm_calc_timestamping_constants(struct drm_crtc *crtc, EXPORT_SYMBOL(drm_calc_timestamping_constants);
/** - * drm_calc_vbltimestamp_from_scanoutpos - helper routine for kms - * drivers. Implements calculation of exact vblank timestamps from - * given drm_display_mode timings and current video scanout position - * of a crtc. This can be called from within get_vblank_timestamp() - * implementation of a kms driver to implement the actual timestamping. + * drm_calc_vbltimestamp_from_scanoutpos - precise vblank timestamp helper + * @dev: DRM device + * @crtc: Which CRTC's vblank timestamp to retrieve + * @max_error: Desired maximum allowable error in timestamps (nanosecs) + * On return contains true maximum error of timestamp + * @vblank_time: Pointer to struct timeval which should receive the timestamp + * @flags: Flags to pass to driver: + * 0 = Default, + * DRM_CALLED_FROM_VBLIRQ = If function is called from vbl IRQ handler + * @refcrtc: CRTC which defines scanout timing + * @mode: mode which defines the scanout timings + * + * Implements calculation of exact vblank timestamps from given drm_display_mode + * timings and current video scanout position of a CRTC. This can be called from + * within get_vblank_timestamp() implementation of a kms driver to implement the + * actual timestamping. * * Should return timestamps conforming to the OML_sync_control OpenML * extension specification. The timestamp corresponds to the end of @@ -478,21 +520,11 @@ EXPORT_SYMBOL(drm_calc_timestamping_constants); * returns as no operation if a doublescan or interlaced video mode is * active. Higher level code is expected to handle this. * - * @dev: DRM device. - * @crtc: Which crtc's vblank timestamp to retrieve. - * @max_error: Desired maximum allowable error in timestamps (nanosecs). - * On return contains true maximum error of timestamp. - * @vblank_time: Pointer to struct timeval which should receive the timestamp. - * @flags: Flags to pass to driver: - * 0 = Default. - * DRM_CALLED_FROM_VBLIRQ = If function is called from vbl irq handler. - * @refcrtc: drm_crtc* of crtc which defines scanout timing. - * @mode: mode which defines the scanout timings - * - * Returns negative value on error, failure or if not supported in current + * Returns: + * Negative value on error, failure or if not supported in current * video mode: * - * -EINVAL - Invalid crtc. + * -EINVAL - Invalid CRTC. * -EAGAIN - Temporary unavailable, e.g., called before initial modeset. * -ENOTSUPP - Function not supported in current display mode. * -EIO - Failed, e.g., due to failed scanout position query. @@ -641,23 +673,23 @@ static struct timeval get_drm_timestamp(void)
/** * drm_get_last_vbltimestamp - retrieve raw timestamp for the most recent - * vblank interval. - * + * vblank interval * @dev: DRM device - * @crtc: which crtc's vblank timestamp to retrieve + * @crtc: which CRTC's vblank timestamp to retrieve * @tvblank: Pointer to target struct timeval which should receive the timestamp * @flags: Flags to pass to driver: - * 0 = Default. - * DRM_CALLED_FROM_VBLIRQ = If function is called from vbl irq handler. + * 0 = Default, + * DRM_CALLED_FROM_VBLIRQ = If function is called from vbl IRQ handler * * Fetches the system timestamp corresponding to the time of the most recent - * vblank interval on specified crtc. May call into kms-driver to + * vblank interval on specified CRTC. May call into kms-driver to * compute the timestamp with a high-precision GPU specific method. * * Returns zero if timestamp originates from uncorrected do_gettimeofday() * call, i.e., it isn't very precisely locked to the true vblank. * - * Returns non-zero if timestamp is considered to be very precise. + * Returns: + * Non-zero if timestamp is considered to be very precise, zero otherwise. */ u32 drm_get_last_vbltimestamp(struct drm_device *dev, int crtc, struct timeval *tvblank, unsigned flags) @@ -692,6 +724,9 @@ EXPORT_SYMBOL(drm_get_last_vbltimestamp); * Fetches the "cooked" vblank count value that represents the number of * vblank events since the system was booted, including lost events due to * modesetting activity. + * + * Returns: + * The software vblank counter. */ u32 drm_vblank_count(struct drm_device *dev, int crtc) { @@ -710,8 +745,7 @@ EXPORT_SYMBOL(drm_vblank_count); * Fetches the "cooked" vblank count value that represents the number of * vblank events since the system was booted, including lost events due to * modesetting activity. Returns corresponding system timestamp of the time - * of the vblank interval that corresponds to the current value vblank counter - * value. + * of the vblank interval that corresponds to the current vblank counter value. */ u32 drm_vblank_count_and_time(struct drm_device *dev, int crtc, struct timeval *vblanktime) @@ -882,7 +916,7 @@ static int drm_vblank_enable(struct drm_device *dev, int crtc) * Acquire a reference count on vblank events to avoid having them disabled * while in use. * - * RETURNS + * Returns: * Zero on success, nonzero on failure. */ int drm_vblank_get(struct drm_device *dev, int crtc) @@ -930,6 +964,13 @@ EXPORT_SYMBOL(drm_vblank_put); * drm_vblank_off - disable vblank events on a CRTC * @dev: DRM device * @crtc: CRTC in question + * + * Drivers can use this function to shut down the vblank interrupt handling when + * disabling a crtc. This function ensures that the latest vblank frame count is + * stored so that drm_vblank_on() can restore it again. + * + * Drivers must use this function when the hardware vblank counter can get + * reset, e.g. when suspending. */ void drm_vblank_off(struct drm_device *dev, int crtc) { @@ -966,6 +1007,11 @@ EXPORT_SYMBOL(drm_vblank_off); * drm_vblank_on - enable vblank events on a CRTC * @dev: DRM device * @crtc: CRTC in question + * + * This functions restores the vblank interrupt state captured with + * drm_vblank_off() again. Note that calls to drm_vblank_on() and + * drm_vblank_off() can be unbalanced and so can also be unconditionaly called + * in driver load code to reflect the current hardware state of the crtc. */ void drm_vblank_on(struct drm_device *dev, int crtc) { @@ -986,6 +1032,21 @@ EXPORT_SYMBOL(drm_vblank_on); * * Account for vblank events across mode setting events, which will likely * reset the hardware frame counter. + * + * This is done by grabbing a temporary vblank reference to ensure that the + * vblank interrupt keeps running across the modeset sequence. With this the + * software-side vblank frame counting will ensure that there are no jumps or + * discontinuities. + * + * Unfortunately this approach is racy and also doesn't work when the vblank + * interrupt stops running, e.g. across system suspend resume. It is therefore + * highly recommended that drivers use the newer drm_vblank_off() and + * drm_vblank_on() instead. drm_vblank_pre_modeset() only works correctly when + * using "cooked" software vblank frame counters and not relying on any hardware + * counters. + * + * Drivers must call drm_vblank_post_modeset() when re-enabling the same crtc + * again. */ void drm_vblank_pre_modeset(struct drm_device *dev, int crtc) { @@ -1007,6 +1068,14 @@ void drm_vblank_pre_modeset(struct drm_device *dev, int crtc) } EXPORT_SYMBOL(drm_vblank_pre_modeset);
+/** + * drm_vblank_post_modeset - undo drm_vblank_pre_modeset changes + * @dev: DRM device + * @crtc: CRTC in question + * + * This function again drops the temporary vblank reference acquired in + * drm_vblank_pre_modeset. + */ void drm_vblank_post_modeset(struct drm_device *dev, int crtc) { unsigned long irqflags; @@ -1028,7 +1097,7 @@ void drm_vblank_post_modeset(struct drm_device *dev, int crtc) } EXPORT_SYMBOL(drm_vblank_post_modeset);
-/** +/* * drm_modeset_ctl - handle vblank event counter changes across mode switch * @DRM_IOCTL_ARGS: standard ioctl arguments * @@ -1141,7 +1210,7 @@ err_put: return ret; }
-/** +/* * Wait for VBLANK. * * \param inode device inode. @@ -1152,7 +1221,7 @@ err_put: * * This function enables the vblank interrupt on the pipe requested, then * sleeps waiting for the requested sequence number to occur, and drops - * the vblank interrupt refcount afterwards. (vblank irq disable follows that + * the vblank interrupt refcount afterwards. (vblank IRQ disable follows that * after a timeout with no further vblank waits scheduled). */ int drm_wait_vblank(struct drm_device *dev, void *data,