Re: [PATCH] drm: Improve manual IRQ installation documentation

On Thu, Jun 20, 2013 at 12:17:25PM +0200, Laurent Pinchart wrote:

Hi Thierry,

On Thursday 20 June 2013 12:10:47 Thierry Reding wrote:

...

On Wed, Jun 19, 2013 at 02:00:45PM +0200, Laurent Pinchart wrote:

...

Signed-off-by: Laurent Pinchart

laurent.pinchart+renesas@ideasonboard.com

Documentation/DocBook/drm.tmpl | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/Documentation/DocBook/drm.tmpl b/Documentation/DocBook/drm.tmpl index f9df3b8..738b727 100644 --- a/Documentation/DocBook/drm.tmpl +++ b/Documentation/DocBook/drm.tmpl @@ -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 & - 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>

@@ -344,7 +345,8 @@ 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.

Perhaps this should mention that if you handle IRQ installation manually you also need to manually set drm->irq_enabled = 1, as otherwise things like DRM_IOCTL_WAIT_VBLANK won't work properly.

That's only needed if DRIVER_HAVE_IRQ is set, otherwise the drm_wait_vblank() function skips the irq_enabled check.

Not quite. There's another check for dev->irq_enabled in the DRM_WAIT_ON() so it'll never actually block. Arguably this could be solved by making the DRM_WAIT_ON() condition drop the !dev->irq_enabled in case DRIVER_HAVE_IRQ isn't set.

I'll see if I can find the time to come up with a patch.

Thierry