drm: Improve manual IRQ installation documentation
Define the rules for using irqs from drm drivers. Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Dave Airlie <airlied@redhat.com>
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@ -186,11 +186,12 @@
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<varlistentry>
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<term>DRIVER_HAVE_IRQ</term><term>DRIVER_IRQ_SHARED</term>
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<listitem><para>
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DRIVER_HAVE_IRQ indicates whether the driver has an IRQ handler. The
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DRM core will automatically register an interrupt handler when the
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flag is set. DRIVER_IRQ_SHARED indicates whether the device &
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handler support shared IRQs (note that this is required of PCI
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drivers).
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DRIVER_HAVE_IRQ indicates whether the driver has an IRQ handler
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managed by the DRM Core. The core will support simple IRQ handler
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installation when the flag is set. The installation process is
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described in <xref linkend="drm-irq-registration"/>.</para>
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<para>DRIVER_IRQ_SHARED indicates whether the device & handler
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support shared IRQs (note that this is required of PCI drivers).
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</para></listitem>
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</varlistentry>
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<varlistentry>
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@ -344,15 +345,18 @@ char *date;</synopsis>
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The DRM core tries to facilitate IRQ handler registration and
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unregistration by providing <function>drm_irq_install</function> and
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<function>drm_irq_uninstall</function> functions. Those functions only
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support a single interrupt per device.
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support a single interrupt per device, devices that use more than one
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IRQs need to be handled manually.
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</para>
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<!--!Fdrivers/char/drm/drm_irq.c drm_irq_install-->
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<sect4>
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<title>Managed IRQ Registration</title>
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<para>
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Both functions get the device IRQ by calling
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<function>drm_dev_to_irq</function>. This inline function will call a
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bus-specific operation to retrieve the IRQ number. For platform devices,
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<function>platform_get_irq</function>(..., 0) is used to retrieve the
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IRQ number.
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Both the <function>drm_irq_install</function> and
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<function>drm_irq_uninstall</function> functions get the device IRQ by
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calling <function>drm_dev_to_irq</function>. This inline function will
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call a bus-specific operation to retrieve the IRQ number. For platform
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devices, <function>platform_get_irq</function>(..., 0) is used to
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retrieve the IRQ number.
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</para>
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<para>
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<function>drm_irq_install</function> starts by calling the
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@ -388,6 +392,24 @@ char *date;</synopsis>
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must disable all hardware interrupts. Finally the function frees the IRQ
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by calling <function>free_irq</function>.
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</para>
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</sect4>
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<sect4>
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<title>Manual IRQ Registration</title>
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<para>
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Drivers that require multiple interrupt handlers can't use the managed
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IRQ registration functions. In that case IRQs must be registered and
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unregistered manually (usually with the <function>request_irq</function>
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and <function>free_irq</function> functions, or their devm_* equivalent).
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</para>
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<para>
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When manually registering IRQs, drivers must not set the DRIVER_HAVE_IRQ
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driver feature flag, and must not provide the
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<methodname>irq_handler</methodname> driver operation. They must set the
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<structname>drm_device</structname> <structfield>irq_enabled</structfield>
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field to 1 upon registration of the IRQs, and clear it to 0 after
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unregistering the IRQs.
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</para>
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</sect4>
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</sect3>
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<sect3>
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<title>Memory Manager Initialization</title>
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