drm/doc: Polish irq helper documentation (16584b20) · Commits · e / devices / android_kernel_oneplus_sm7250

Documentation/gpu/drm-internals.rst

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		@@ -149,60 +149,6 @@ Device Instance and Driver Handling
		Driver Load
		-----------

		IRQ Registration
		~~~~~~~~~~~~~~~~

		The DRM core tries to facilitate IRQ handler registration and
		unregistration by providing :c:func:`drm_irq_install()` and
		:c:func:`drm_irq_uninstall()` functions. Those functions only
		support a single interrupt per device, devices that use more than one
		IRQs need to be handled manually.

		Managed IRQ Registration
		''''''''''''''''''''''''

		:c:func:`drm_irq_install()` starts by calling the irq_preinstall
		driver operation. The operation is optional and must make sure that the
		interrupt will not get fired by clearing all pending interrupt flags or
		disabling the interrupt.

		The passed-in IRQ will then be requested by a call to
		:c:func:`request_irq()`. If the DRIVER_IRQ_SHARED driver feature
		flag is set, a shared (IRQF_SHARED) IRQ handler will be requested.

		The IRQ handler function must be provided as the mandatory irq_handler
		driver operation. It will get passed directly to
		:c:func:`request_irq()` and thus has the same prototype as all IRQ
		handlers. It will get called with a pointer to the DRM device as the
		second argument.

		Finally the function calls the optional irq_postinstall driver
		operation. The operation usually enables interrupts (excluding the
		vblank interrupt, which is enabled separately), but drivers may choose
		to enable/disable interrupts at a different time.

		:c:func:`drm_irq_uninstall()` is similarly used to uninstall an
		IRQ handler. It starts by waking up all processes waiting on a vblank
		interrupt to make sure they don't hang, and then calls the optional
		irq_uninstall driver operation. The operation must disable all hardware
		interrupts. Finally the function frees the IRQ by calling
		:c:func:`free_irq()`.

		Manual IRQ Registration
		'''''''''''''''''''''''

		Drivers that require multiple interrupt handlers can't use the managed
		IRQ registration functions. In that case IRQs must be registered and
		unregistered manually (usually with the :c:func:`request_irq()` and
		:c:func:`free_irq()` functions, or their :c:func:`devm_request_irq()` and
		:c:func:`devm_free_irq()` equivalents).

		When manually registering IRQs, drivers must not set the
		DRIVER_HAVE_IRQ driver feature flag, and must not provide the
		irq_handler driver operation. They must set the :c:type:`struct
		drm_device <drm_device>` irq_enabled field to 1 upon
		registration of the IRQs, and clear it to 0 after unregistering the
		IRQs.

		IRQ Helper Library
		~~~~~~~~~~~~~~~~~~

drivers/gpu/drm/drm_irq.c

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		@@ -61,20 +61,40 @@

		#include "drm_internal.h"

		/**
		* DOC: irq helpers
		*
		* The DRM core provides very simple support helpers to enable IRQ handling on a
		* device through the drm_irq_install() and drm_irq_uninstall() functions. This
		* only supports devices with a single interrupt on the main device stored in
		* &drm_device.dev and set as the device paramter in drm_dev_alloc().
		*
		* These IRQ helpers are strictly optional. Drivers which roll their own only
		* need to set &drm_device.irq_enabled to signal the DRM core that vblank
		* interrupts are working. Since these helpers don't automatically clean up the
		* requested interrupt like e.g. devm_request_irq() they're not really
		* recommended.
		*/

		/**
		* 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
		* irq_preinstall() and irq_postinstall() functions before and after the
		* installation.
		* &drm_driver.irq_preinstall and &drm_driver.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.
		*
		* @irq must match the interrupt number that would be passed to request_irq(),
		* if called directly instead of using this helper function.
		*
		* &drm_driver.irq_handler is called to handle the registered interrupt.
		*
		* Returns:
		* Zero on success or a negative error code on failure.
		*/
		@@ -136,9 +156,9 @@ EXPORT_SYMBOL(drm_irq_install);
		* 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
		* Calls the driver's &drm_driver.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.
		*
		* Note that for kernel modesetting drivers it is a bug if this function fails.

drivers/gpu/drm/drm_vblank.c

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		@@ -363,6 +363,9 @@ static void vblank_disable_fn(unsigned long arg)
		* @dev: DRM device
		*
		* This function cleans up any resources allocated in drm_vblank_init.
		*
		* Drivers which don't use drm_irq_install() need to set &drm_device.irq_enabled
		* themselves, to signal to the DRM core that vblank interrupts are enabled.
		*/
		void drm_vblank_cleanup(struct drm_device *dev)
		{

include/drm/drmP.h

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		@@ -377,8 +377,13 @@ struct drm_device {
		int last_context; /*< Last current context /
		/@} /

		/** \name VBLANK IRQ support */
		/@{ /
		/**
		* @irq_enabled:
		*
		* Indicates that interrupt handling is enabled, specifically vblank
		* handling. Drivers which don't use drm_irq_install() need to set this
		* to true manually.
		*/
		bool irq_enabled;
		int irq;

include/drm/drm_drv.h

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		@@ -327,11 +327,40 @@ struct drm_driver {
		struct timeval *vblank_time,
		bool in_vblank_irq);

		/* these have to be filled in */

		/**
		* @irq_handler:
		*
		* Interrupt handler called when using drm_irq_install(). Not used by
		* drivers which implement their own interrupt handling.
		*/
		irqreturn_t(irq_handler) (int irq, void arg);

		/**
		* @irq_preinstall:
		*
		* Optional callback used by drm_irq_install() which is called before
		* the interrupt handler is registered. This should be used to clear out
		* any pending interrupts (from e.g. firmware based drives) and reset
		* the interrupt handling registers.
		*/
		void (irq_preinstall) (struct drm_device dev);

		/**
		* @irq_postinstall:
		*
		* Optional callback used by drm_irq_install() which is called after
		* the interrupt handler is registered. This should be used to enable
		* interrupt generation in the hardware.
		*/
		int (irq_postinstall) (struct drm_device dev);

		/**
		* @irq_uninstall:
		*
		* Optional callback used by drm_irq_uninstall() which is called before
		* the interrupt handler is unregistered. This should be used to disable
		* interrupt generation in the hardware.
		*/
		void (irq_uninstall) (struct drm_device dev);

		/**