From 02b6298541f8a711b3f9cf589f7e508bd5cb99d8 Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Sat, 22 Jun 2013 14:10:59 +0200 Subject: drm: Improve manual IRQ installation documentation Define the rules for using irqs from drm drivers. Signed-off-by: Laurent Pinchart Reviewed-by: Daniel Vetter Signed-off-by: Dave Airlie --- Documentation/DocBook/drm.tmpl | 118 ++++++++++++++++++++++++----------------- 1 file changed, 70 insertions(+), 48 deletions(-) diff --git a/Documentation/DocBook/drm.tmpl b/Documentation/DocBook/drm.tmpl index 91ee107d5d0e..a6080941f5e4 100644 --- a/Documentation/DocBook/drm.tmpl +++ b/Documentation/DocBook/drm.tmpl @@ -186,11 +186,12 @@ DRIVER_HAVE_IRQDRIVER_IRQ_SHARED - DRIVER_HAVE_IRQ indicates whether the driver has an IRQ handler. The - DRM core will automatically register an interrupt handler when the - flag is set. DRIVER_IRQ_SHARED indicates whether the device & - handler support shared IRQs (note that this is required of PCI - drivers). + DRIVER_HAVE_IRQ indicates whether the driver has an IRQ handler + managed by the DRM Core. The core will support simple IRQ handler + installation when the flag is set. The installation process is + described in . + DRIVER_IRQ_SHARED indicates whether the device & handler + support shared IRQs (note that this is required of PCI drivers). @@ -344,50 +345,71 @@ char *date; The DRM core tries to facilitate IRQ handler registration and unregistration by providing drm_irq_install and drm_irq_uninstall functions. Those functions only - support a single interrupt per device. - - - - Both functions get the device IRQ by calling - drm_dev_to_irq. This inline function will call a - bus-specific operation to retrieve the IRQ number. For platform devices, - platform_get_irq(..., 0) is used to retrieve the - IRQ number. - - - 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 IRQ will then be requested by a call to - 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 - 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. - - - 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 free_irq. + support a single interrupt per device, devices that use more than one + IRQs need to be handled manually. + + Managed IRQ Registration + + Both the drm_irq_install and + drm_irq_uninstall functions get the device IRQ by + calling drm_dev_to_irq. This inline function will + call a bus-specific operation to retrieve the IRQ number. For platform + devices, platform_get_irq(..., 0) is used to + retrieve the IRQ number. + + + 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 IRQ will then be requested by a call to + 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 + 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. + + + 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 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 request_irq + and free_irq functions, or their devm_* equivalent). + + + 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 + drm_device irq_enabled + field to 1 upon registration of the IRQs, and clear it to 0 after + unregistering the IRQs. + + Memory Manager Initialization -- cgit v1.2.3