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Date: Mon, 1 Sep 2014 11:02:33 +0100
From: Chris Wilson <chris@...is-wilson.co.uk>
To: Ville Syrjälä <ville.syrjala@...ux.intel.com>
Cc: intel-gfx@...ts.freedesktop.org, David Airlie <airlied@...ux.ie>,
Daniel Vetter <daniel.vetter@...ll.ch>,
linux-kernel@...r.kernel.org, Tibor Billes <tbilles@....com>
Subject: Re: [Intel-gfx] [PATCH] drm/i915: Fix lock dropping in
intel_tv_detect()
On Mon, Sep 01, 2014 at 12:45:56PM +0300, Ville Syrjälä wrote:
> On Mon, Sep 01, 2014 at 09:50:22AM +0100, Chris Wilson wrote:
> > diff --git a/drivers/gpu/drm/i915/intel_tv.c b/drivers/gpu/drm/i915/intel_tv.c
> > index 32186a6..a109b7b 100644
> > --- a/drivers/gpu/drm/i915/intel_tv.c
> > +++ b/drivers/gpu/drm/i915/intel_tv.c
> > @@ -1311,6 +1311,7 @@ intel_tv_detect(struct drm_connector *connector, bool force)
> > {
> > struct drm_display_mode mode;
> > struct intel_tv *intel_tv = intel_attached_tv(connector);
> > + enum drm_connector_status status = connector->status;
> > int type;
> >
> > DRM_DEBUG_KMS("[CONNECTOR:%d:%s] force=%d\n",
> > @@ -1327,17 +1328,20 @@ intel_tv_detect(struct drm_connector *connector, bool force)
> >
> > if (intel_get_load_detect_pipe(connector, &mode, &tmp, &ctx)) {
> > type = intel_tv_detect_type(intel_tv, connector);
> > + status = type < 0 ?
> > + connector_status_disconnected :
> > + connector_status_connected;
> > +
> > intel_release_load_detect_pipe(connector, &tmp);
> > } else
> > - return connector_status_unknown;
> > + status = connector_status_unknown;
> >
> > drm_modeset_drop_locks(&ctx);
> > drm_modeset_acquire_fini(&ctx);
> > - } else
> > - return connector->status;
> > + }
> >
> > - if (type < 0)
> > - return connector_status_disconnected;
> > + if (status != connector_status_connected)
> > + return status;
> >
> > intel_tv->type = type;
> > intel_tv_find_better_format(connector);
>
> With this approach we're going to have to keep the !force else branch
> to avoid populating intel_tv->type with stack garbage. But I suppose
> the resulting code might still be a bit clearer.
Or just set intel_tv->type directly inside
status = intel_tv_detect_type() ?
Hmm. Indeed, we should not be touching them at all for !forced, as type
is only set for forced, and so we can similarly ignore hpd of better
formats.
diff --git a/drivers/gpu/drm/i915/intel_tv.c b/drivers/gpu/drm/i915/intel_tv.c
index 32186a656816..e80eac5e5239 100644
--- a/drivers/gpu/drm/i915/intel_tv.c
+++ b/drivers/gpu/drm/i915/intel_tv.c
@@ -1169,7 +1169,7 @@ static const struct drm_display_mode reported_modes[] = {
* \return true if TV is connected.
* \return false if TV is disconnected.
*/
-static int
+static enum drm_connector_status
intel_tv_detect_type(struct intel_tv *intel_tv,
struct drm_connector *connector)
{
@@ -1178,10 +1178,10 @@ intel_tv_detect_type(struct intel_tv *intel_tv,
struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
struct drm_device *dev = encoder->dev;
struct drm_i915_private *dev_priv = dev->dev_private;
+ enum drm_connector_status status;
unsigned long irqflags;
u32 tv_ctl, save_tv_ctl;
u32 tv_dac, save_tv_dac;
- int type;
/* Disable TV interrupts around load detect or we'll recurse */
if (connector->polled & DRM_CONNECTOR_POLL_HPD) {
@@ -1229,7 +1229,6 @@ intel_tv_detect_type(struct intel_tv *intel_tv,
intel_wait_for_vblank(intel_tv->base.base.dev,
to_intel_crtc(intel_tv->base.base.crtc)->pipe);
- type = -1;
tv_dac = I915_READ(TV_DAC);
DRM_DEBUG_KMS("TV detected: %x, %x\n", tv_ctl, tv_dac);
/*
@@ -1238,18 +1237,19 @@ intel_tv_detect_type(struct intel_tv *intel_tv,
* 1 0 X svideo
* 0 0 0 Component
*/
+ status = connector_status_connected;
if ((tv_dac & TVDAC_SENSE_MASK) == (TVDAC_B_SENSE | TVDAC_C_SENSE)) {
DRM_DEBUG_KMS("Detected Composite TV connection\n");
- type = DRM_MODE_CONNECTOR_Composite;
+ intel_tv->type = DRM_MODE_CONNECTOR_Composite;
} else if ((tv_dac & (TVDAC_A_SENSE|TVDAC_B_SENSE)) == TVDAC_A_SENSE) {
DRM_DEBUG_KMS("Detected S-Video TV connection\n");
- type = DRM_MODE_CONNECTOR_SVIDEO;
+ intel_tv->type = DRM_MODE_CONNECTOR_SVIDEO;
} else if ((tv_dac & TVDAC_SENSE_MASK) == 0) {
DRM_DEBUG_KMS("Detected Component TV connection\n");
- type = DRM_MODE_CONNECTOR_Component;
+ intel_tv->type = DRM_MODE_CONNECTOR_Component;
} else {
DRM_DEBUG_KMS("Unrecognised TV connection\n");
- type = -1;
+ status = connector_status_disconnected;
}
I915_WRITE(TV_DAC, save_tv_dac & ~TVDAC_STATE_CHG_EN);
@@ -1269,7 +1269,7 @@ intel_tv_detect_type(struct intel_tv *intel_tv,
spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
}
- return type;
+ return status;
}
/*
@@ -1309,39 +1309,33 @@ static void intel_tv_find_better_format(struct drm_connector *connector)
static enum drm_connector_status
intel_tv_detect(struct drm_connector *connector, bool force)
{
- struct drm_display_mode mode;
struct intel_tv *intel_tv = intel_attached_tv(connector);
- int type;
+ struct drm_display_mode mode = reported_modes[0];
+ struct intel_load_detect_pipe tmp;
+ struct drm_modeset_acquire_ctx ctx;
+ enum drm_connector_status status;
DRM_DEBUG_KMS("[CONNECTOR:%d:%s] force=%d\n",
connector->base.id, connector->name,
force);
+ if (!force)
+ return connector->status;
- mode = reported_modes[0];
-
- if (force) {
- struct intel_load_detect_pipe tmp;
- struct drm_modeset_acquire_ctx ctx;
-
- drm_modeset_acquire_init(&ctx, 0);
-
- if (intel_get_load_detect_pipe(connector, &mode, &tmp, &ctx)) {
- type = intel_tv_detect_type(intel_tv, connector);
- intel_release_load_detect_pipe(connector, &tmp);
- } else
- return connector_status_unknown;
+ drm_modeset_acquire_init(&ctx, 0);
- drm_modeset_drop_locks(&ctx);
- drm_modeset_acquire_fini(&ctx);
+ if (intel_get_load_detect_pipe(connector, &mode, &tmp, &ctx)) {
+ status = intel_tv_detect_type(intel_tv, connector);
+ intel_release_load_detect_pipe(connector, &tmp);
} else
- return connector->status;
+ status = connector_status_unknown;
- if (type < 0)
- return connector_status_disconnected;
+ drm_modeset_drop_locks(&ctx);
+ drm_modeset_acquire_fini(&ctx);
- intel_tv->type = type;
- intel_tv_find_better_format(connector);
+ if (status != connector
+ return status;
+ intel_tv_find_better_format(connector);
return connector_status_connected;
}
--
Chris Wilson, Intel Open Source Technology Centre
--
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