From 7d14bb6b537414ffe6a8641cb14088465c28460d Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Thu, 8 Aug 2013 15:41:15 +0200 Subject: drm: don't call ->firstopen for KMS drivers It has way too much potential for driver writers to do stupid things like delayed hw setup because the load sequence is somehow racy (e.g. the imx driver in staging). So don't call it for modesetting drivers, which reduces the complexity of the drm core -> driver interface a notch. v2: Don't forget to update DocBook. v3: Go with Laurent's slightly more elaborate proposal for the DocBook update. Add a few words on top of his diff to elaborate a bit on what KMS drivers should and shouldn't do in lastclose. There was already a paragraph present talking about restoring properties, I've simply extended that one. Cc: Laurent Pinchart Acked-by: Laurent Pinchart Signed-off-by: Daniel Vetter Signed-off-by: Dave Airlie --- Documentation/DocBook/drm.tmpl | 27 ++++++++++++++++----------- 1 file changed, 16 insertions(+), 11 deletions(-) (limited to 'Documentation/DocBook') diff --git a/Documentation/DocBook/drm.tmpl b/Documentation/DocBook/drm.tmpl index 6869b9b534b5..9fc8ed4ac0f4 100644 --- a/Documentation/DocBook/drm.tmpl +++ b/Documentation/DocBook/drm.tmpl @@ -2405,18 +2405,18 @@ void (*postclose) (struct drm_device *, struct drm_file *); The firstopen method is called by the DRM core - when an application opens a device that has no other opened file handle. - Similarly the lastclose method is called when - the last application holding a file handle opened on the device closes - it. Both methods are mostly used for UMS (User Mode Setting) drivers to - acquire and release device resources which should be done in the - load and unload - methods for KMS drivers. + for legacy UMS (User Mode Setting) drivers only when an application + opens a device that has no other opened file handle. UMS drivers can + implement it to acquire device resources. KMS drivers can't use the + method and must acquire resources in the load + method instead. - Note that the lastclose method is also called - at module unload time or, for hot-pluggable devices, when the device is - unplugged. The firstopen and + Similarly the lastclose method is called when + the last application holding a file handle opened on the device closes + it, for both UMS and KMS drivers. Additionally, the method is also + called at module unload time or, for hot-pluggable devices, when the + device is unplugged. The firstopen and lastclose calls can thus be unbalanced. @@ -2445,7 +2445,12 @@ void (*postclose) (struct drm_device *, struct drm_file *); The lastclose method should restore CRTC and plane properties to default value, so that a subsequent open of the - device will not inherit state from the previous user. + device will not inherit state from the previous user. It can also be + used to execute delayed power switching state changes, e.g. in + conjunction with the vga-switcheroo infrastructure. Beyond that KMS + drivers should not do any further cleanup. Only legacy UMS drivers might + need to clean up device state so that the vga console or an independent + fbdev driver could take over. -- cgit v1.2.3