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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>
hifive-unleashed-5.1
Laurent Pinchart 2013-06-22 14:10:59 +02:00 committed by Dave Airlie
parent da34242e5e
commit 02b6298541
1 changed files with 70 additions and 48 deletions
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46
Documentation/DocBook/drm.tmpl
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@ -186,11 +186,12 @@
<varlistentry>
<term>DRIVER_HAVE_IRQ</term><term>DRIVER_IRQ_SHARED</term>
<listitem><para>
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 &amp;
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 <xref linkend="drm-irq-registration"/>.</para>
<para>DRIVER_IRQ_SHARED indicates whether the device &amp; handler
support shared IRQs (note that this is required of PCI drivers).
</para></listitem>
</varlistentry>
<varlistentry>
@ -344,15 +345,18 @@ char *date;</synopsis>
The DRM core tries to facilitate IRQ handler registration and
unregistration by providing <function>drm_irq_install</function> and
<function>drm_irq_uninstall</function> functions. Those functions only
support a single interrupt per device.
support a single interrupt per device, devices that use more than one
IRQs need to be handled manually.
</para>
<!--!Fdrivers/char/drm/drm_irq.c drm_irq_install-->
<sect4>
<title>Managed IRQ Registration</title>
<para>
Both functions get the device IRQ by calling
<function>drm_dev_to_irq</function>. This inline function will call a
bus-specific operation to retrieve the IRQ number. For platform devices,
<function>platform_get_irq</function>(..., 0) is used to retrieve the
IRQ number.
Both the <function>drm_irq_install</function> and
<function>drm_irq_uninstall</function> functions get the device IRQ by
calling <function>drm_dev_to_irq</function>. This inline function will
call a bus-specific operation to retrieve the IRQ number. For platform
devices, <function>platform_get_irq</function>(..., 0) is used to
retrieve the IRQ number.
</para>
<para>
<function>drm_irq_install</function> starts by calling the
@ -388,6 +392,24 @@ char *date;</synopsis>
must disable all hardware interrupts. Finally the function frees the IRQ
by calling <function>free_irq</function>.
</para>
</sect4>
<sect4>
<title>Manual IRQ Registration</title>
<para>
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 <function>request_irq</function>
and <function>free_irq</function> functions, or their devm_* equivalent).
</para>
<para>
When manually registering IRQs, drivers must not set the DRIVER_HAVE_IRQ
driver feature flag, and must not provide the
<methodname>irq_handler</methodname> driver operation. They must set the
<structname>drm_device</structname> <structfield>irq_enabled</structfield>
field to 1 upon registration of the IRQs, and clear it to 0 after
unregistering the IRQs.
</para>
</sect4>
</sect3>
<sect3>
<title>Memory Manager Initialization</title>