| Message ID | 202b0a53ecee8d3104d25b22758dc0dffb156cef.1473148345.git.jsarha@ti.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 06/09/16 11:19, Jyri Sarha wrote: > Take mode config lock while updating the crtc clock rate. To avoid a > race in tilcdc_crtc_update_clk(), we do not want the mode to change > while we update crtc clock. > > Signed-off-by: Jyri Sarha <jsarha@ti.com> > --- > drivers/gpu/drm/tilcdc/tilcdc_drv.c | 5 +++++ > drivers/gpu/drm/tilcdc/tilcdc_drv.h | 2 ++ > 2 files changed, 7 insertions(+) > > diff --git a/drivers/gpu/drm/tilcdc/tilcdc_drv.c b/drivers/gpu/drm/tilcdc/tilcdc_drv.c > index f8892e9..882d9b5 100644 > --- a/drivers/gpu/drm/tilcdc/tilcdc_drv.c > +++ b/drivers/gpu/drm/tilcdc/tilcdc_drv.c > @@ -184,10 +184,14 @@ static int cpufreq_transition(struct notifier_block *nb, > { > struct tilcdc_drm_private *priv = container_of(nb, > struct tilcdc_drm_private, freq_transition); > + struct drm_mode_config *config = &priv->dev->mode_config; > + > if (val == CPUFREQ_POSTCHANGE) { > if (priv->lcd_fck_rate != clk_get_rate(priv->clk)) { > + mutex_lock(&config->mutex); drm_modeset_lock_crtc()? Or drm_modeset_lock_all() if per-crtc is not suitable. Tomi
On 09/06/16 12:07, Tomi Valkeinen wrote: > > > On 06/09/16 11:19, Jyri Sarha wrote: >> Take mode config lock while updating the crtc clock rate. To avoid a >> race in tilcdc_crtc_update_clk(), we do not want the mode to change >> while we update crtc clock. >> >> Signed-off-by: Jyri Sarha <jsarha@ti.com> >> --- >> drivers/gpu/drm/tilcdc/tilcdc_drv.c | 5 +++++ >> drivers/gpu/drm/tilcdc/tilcdc_drv.h | 2 ++ >> 2 files changed, 7 insertions(+) >> >> diff --git a/drivers/gpu/drm/tilcdc/tilcdc_drv.c b/drivers/gpu/drm/tilcdc/tilcdc_drv.c >> index f8892e9..882d9b5 100644 >> --- a/drivers/gpu/drm/tilcdc/tilcdc_drv.c >> +++ b/drivers/gpu/drm/tilcdc/tilcdc_drv.c >> @@ -184,10 +184,14 @@ static int cpufreq_transition(struct notifier_block *nb, >> { >> struct tilcdc_drm_private *priv = container_of(nb, >> struct tilcdc_drm_private, freq_transition); >> + struct drm_mode_config *config = &priv->dev->mode_config; >> + >> if (val == CPUFREQ_POSTCHANGE) { >> if (priv->lcd_fck_rate != clk_get_rate(priv->clk)) { >> + mutex_lock(&config->mutex); > > drm_modeset_lock_crtc()? Or drm_modeset_lock_all() if per-crtc is not > suitable. > I guess that should work too, all I need is just to make sure no one calls mode_set_nofb() while the clock is updated. I just thought that since I am not actually touching drm state at all the back off mechanisms etc add just unnecessary complexity. But now after reading a little bit drm locking code, for sure the mode config mutex is not the light weight lock I was looking for. One solution would be adding tilcdc internal mutex to synchronize mode_set_nofb() and cpufreq_transition(), but after all it is probably better to use the mechanisms that are already there and just use drm_modeset_lock_crtc() despite its apparent complexity. BR, Jyri
diff --git a/drivers/gpu/drm/tilcdc/tilcdc_drv.c b/drivers/gpu/drm/tilcdc/tilcdc_drv.c index f8892e9..882d9b5 100644 --- a/drivers/gpu/drm/tilcdc/tilcdc_drv.c +++ b/drivers/gpu/drm/tilcdc/tilcdc_drv.c @@ -184,10 +184,14 @@ static int cpufreq_transition(struct notifier_block *nb, { struct tilcdc_drm_private *priv = container_of(nb, struct tilcdc_drm_private, freq_transition); + struct drm_mode_config *config = &priv->dev->mode_config; + if (val == CPUFREQ_POSTCHANGE) { if (priv->lcd_fck_rate != clk_get_rate(priv->clk)) { + mutex_lock(&config->mutex); priv->lcd_fck_rate = clk_get_rate(priv->clk); tilcdc_crtc_update_clk(priv->crtc); + mutex_unlock(&config->mutex); } } @@ -251,6 +255,7 @@ static int tilcdc_load(struct drm_device *dev, unsigned long flags) } dev->dev_private = priv; + priv->dev = dev; priv->is_componentized = tilcdc_get_external_components(dev->dev, NULL) > 0; diff --git a/drivers/gpu/drm/tilcdc/tilcdc_drv.h b/drivers/gpu/drm/tilcdc/tilcdc_drv.h index a6e5e6d..6caecfc 100644 --- a/drivers/gpu/drm/tilcdc/tilcdc_drv.h +++ b/drivers/gpu/drm/tilcdc/tilcdc_drv.h @@ -49,6 +49,8 @@ struct tilcdc_drm_private { void __iomem *mmio; + struct drm_device *dev; + struct clk *clk; /* functional clock */ int rev; /* IP revision */
Take mode config lock while updating the crtc clock rate. To avoid a race in tilcdc_crtc_update_clk(), we do not want the mode to change while we update crtc clock. Signed-off-by: Jyri Sarha <jsarha@ti.com> --- drivers/gpu/drm/tilcdc/tilcdc_drv.c | 5 +++++ drivers/gpu/drm/tilcdc/tilcdc_drv.h | 2 ++ 2 files changed, 7 insertions(+)