linux-kernel - [PATCH v3 1/2] drm/file: Rehabilitate the firstopen hook for non-legacy drivers

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Date:   Thu, 28 Mar 2019 17:13:05 +0100
From:   Paul Kocialkowski <paul.kocialkowski@...tlin.com>
To:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Cc:     Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <maxime.ripard@...tlin.com>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, Eric Anholt <eric@...olt.net>,
        Eben Upton <eben@...pberrypi.org>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Paul Kocialkowski <paul.kocialkowski@...tlin.com>
Subject: [PATCH v3 1/2] drm/file: Rehabilitate the firstopen hook for non-legacy drivers

The firstopen DRM driver hook was initially used to perform hardware
initialization, which is now considered legacy. Only a single user of
firstopen remains at this point (savage).

In some specific cases, non-legacy drivers may also need to implement
these hooks. For instance on VC4, we need to allocate a 16 MiB buffer
for the GPU. Because it's not required for fbcon, it's a waste to
allocate it before userspace starts using the DRM device.

Using firstopen and lastclose for this allocation seems like the best
fit, so re-habilitate the hook to allow it to be called for non-legacy
drivers.

Signed-off-by: Paul Kocialkowski <paul.kocialkowski@...tlin.com>
Reviewed-by: Eric Anholt <eric@...olt.net>
---
 drivers/gpu/drm/drm_file.c | 3 +--
 include/drm/drm_drv.h      | 3 ---
 2 files changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
index b1838a41ad43..c011b5cbfb6b 100644
--- a/drivers/gpu/drm/drm_file.c
+++ b/drivers/gpu/drm/drm_file.c
@@ -266,8 +266,7 @@ static int drm_setup(struct drm_device * dev)
 {
 	int ret;
 
-	if (dev->driver->firstopen &&
-	    drm_core_check_feature(dev, DRIVER_LEGACY)) {
+	if (dev->driver->firstopen) {
 		ret = dev->driver->firstopen(dev);
 		if (ret != 0)
 			return ret;
diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
index ca46a45a9cce..de5637494503 100644
--- a/include/drm/drm_drv.h
+++ b/include/drm/drm_drv.h
@@ -234,9 +234,6 @@ struct drm_driver {
 	 * kernel driver does not really own the hardware. Instead ownershipe is
 	 * handled with the help of userspace through an inheritedly racy dance
 	 * to set/unset the VT into raw mode.
-	 *
-	 * Legacy drivers initialize the hardware in the @firstopen callback,
-	 * which isn't even called for modern drivers.
 	 */
 	void (*lastclose) (struct drm_device *);
 
-- 
2.21.0