From: Sam Ravnborg <sam@ravnborg.org> To: Bjorn Andersson <bjorn.andersson@linaro.org> Cc: Thierry Reding <thierry.reding@gmail.com>, Maarten Lankhorst <maarten.lankhorst@linux.intel.com>, Maxime Ripard <mripard@kernel.org>, Thomas Zimmermann <tzimmermann@suse.de>, David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH] drm/panel: Make backlight attachment lazy Date: Tue, 8 Dec 2020 06:48:55 +0100 [thread overview] Message-ID: <20201208054855.GA18863@ravnborg.org> (raw) In-Reply-To: <20201208044446.973238-1-bjorn.andersson@linaro.org> Hi Bjorn, On Mon, Dec 07, 2020 at 10:44:46PM -0600, Bjorn Andersson wrote: > Some bridge chips, such as the TI SN65DSI86 DSI/eDP bridge, provides > means of generating a PWM signal for backlight control of the attached > panel. The provided PWM chip is typically controlled by the > pwm-backlight driver, which if tied to the panel will provide DPMS. > > But with the current implementation the panel will refuse to probe > because the bridge driver has yet to probe and register the PWM chip, > and the bridge driver will refuse to probe because it's unable to find > the panel. > > Mitigate this catch-22 situation by allowing the panel driver to probe > and retry the attachment of the backlight as the panel is turned on or > off. > > Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> > --- > drivers/gpu/drm/drm_panel.c | 47 +++++++++++++++++++++++++++---------- > include/drm/drm_panel.h | 8 +++++++ > 2 files changed, 43 insertions(+), 12 deletions(-) > > diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c > index f634371c717a..7487329bd22d 100644 > --- a/drivers/gpu/drm/drm_panel.c > +++ b/drivers/gpu/drm/drm_panel.c > @@ -43,6 +43,34 @@ static LIST_HEAD(panel_list); > * take look at drm_panel_bridge_add() and devm_drm_panel_bridge_add(). > */ > > +#if IS_REACHABLE(CONFIG_BACKLIGHT_CLASS_DEVICE) > +static int drm_panel_of_backlight_lazy(struct drm_panel *panel) > +{ > + struct backlight_device *backlight; > + > + if (!panel || !panel->dev) > + return -EINVAL; > + > + backlight = devm_of_find_backlight(panel->dev); > + > + if (IS_ERR(backlight)) { > + if (PTR_ERR(backlight) == -EPROBE_DEFER) { > + panel->backlight_init_pending = true; > + return 0; > + } > + > + return PTR_ERR(backlight); Use dev_err_probe() > + } > + > + panel->backlight = backlight; > + panel->backlight_init_pending = false; > + > + return 0; > +} > +#else > +static int drm_panel_of_backlight_lazy(struct drm_panel *panel) { return 0; } > +#endif > + > /** > * drm_panel_init - initialize a panel > * @panel: DRM panel > @@ -161,6 +189,9 @@ int drm_panel_enable(struct drm_panel *panel) > return ret; > } > > + if (panel->backlight_init_pending) > + drm_panel_of_backlight_lazy(panel); > + > ret = backlight_enable(panel->backlight); > if (ret < 0) > DRM_DEV_INFO(panel->dev, "failed to enable backlight: %d\n", > @@ -187,6 +218,9 @@ int drm_panel_disable(struct drm_panel *panel) > if (!panel) > return -EINVAL; > > + if (panel->backlight_init_pending) > + drm_panel_of_backlight_lazy(panel); > + > ret = backlight_disable(panel->backlight); > if (ret < 0) > DRM_DEV_INFO(panel->dev, "failed to disable backlight: %d\n", > @@ -328,18 +362,7 @@ EXPORT_SYMBOL(of_drm_get_panel_orientation); > */ > int drm_panel_of_backlight(struct drm_panel *panel) > { > - struct backlight_device *backlight; > - > - if (!panel || !panel->dev) > - return -EINVAL; > - > - backlight = devm_of_find_backlight(panel->dev); > - > - if (IS_ERR(backlight)) > - return PTR_ERR(backlight); > - > - panel->backlight = backlight; > - return 0; > + return drm_panel_of_backlight_lazy(panel); Could you update the drm_panel_of_backlight() implementation (and do not forget the documentation) and avoid drm_panel_of_backlight_lazy()? Sam > } > EXPORT_SYMBOL(drm_panel_of_backlight); > #endif > diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h > index 33605c3f0eba..b126abebb2f3 100644 > --- a/include/drm/drm_panel.h > +++ b/include/drm/drm_panel.h > @@ -149,6 +149,14 @@ struct drm_panel { > */ > struct backlight_device *backlight; > > + /** > + * @backlight_init_pending > + * > + * Backlight driver is not yet available so further attempts to > + * initialize @backlight is necessary. > + */ > + bool backlight_init_pending; > + We have not done so today for other fields, but it would be good to document this is for drm_panel use only and drivers shall not touch. Sam
WARNING: multiple messages have this Message-ID (diff)
From: Sam Ravnborg <sam@ravnborg.org> To: Bjorn Andersson <bjorn.andersson@linaro.org> Cc: Thomas Zimmermann <tzimmermann@suse.de>, David Airlie <airlied@linux.ie>, linux-kernel@vger.kernel.org, Thierry Reding <thierry.reding@gmail.com>, dri-devel@lists.freedesktop.org Subject: Re: [RFC PATCH] drm/panel: Make backlight attachment lazy Date: Tue, 8 Dec 2020 06:48:55 +0100 [thread overview] Message-ID: <20201208054855.GA18863@ravnborg.org> (raw) In-Reply-To: <20201208044446.973238-1-bjorn.andersson@linaro.org> Hi Bjorn, On Mon, Dec 07, 2020 at 10:44:46PM -0600, Bjorn Andersson wrote: > Some bridge chips, such as the TI SN65DSI86 DSI/eDP bridge, provides > means of generating a PWM signal for backlight control of the attached > panel. The provided PWM chip is typically controlled by the > pwm-backlight driver, which if tied to the panel will provide DPMS. > > But with the current implementation the panel will refuse to probe > because the bridge driver has yet to probe and register the PWM chip, > and the bridge driver will refuse to probe because it's unable to find > the panel. > > Mitigate this catch-22 situation by allowing the panel driver to probe > and retry the attachment of the backlight as the panel is turned on or > off. > > Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> > --- > drivers/gpu/drm/drm_panel.c | 47 +++++++++++++++++++++++++++---------- > include/drm/drm_panel.h | 8 +++++++ > 2 files changed, 43 insertions(+), 12 deletions(-) > > diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c > index f634371c717a..7487329bd22d 100644 > --- a/drivers/gpu/drm/drm_panel.c > +++ b/drivers/gpu/drm/drm_panel.c > @@ -43,6 +43,34 @@ static LIST_HEAD(panel_list); > * take look at drm_panel_bridge_add() and devm_drm_panel_bridge_add(). > */ > > +#if IS_REACHABLE(CONFIG_BACKLIGHT_CLASS_DEVICE) > +static int drm_panel_of_backlight_lazy(struct drm_panel *panel) > +{ > + struct backlight_device *backlight; > + > + if (!panel || !panel->dev) > + return -EINVAL; > + > + backlight = devm_of_find_backlight(panel->dev); > + > + if (IS_ERR(backlight)) { > + if (PTR_ERR(backlight) == -EPROBE_DEFER) { > + panel->backlight_init_pending = true; > + return 0; > + } > + > + return PTR_ERR(backlight); Use dev_err_probe() > + } > + > + panel->backlight = backlight; > + panel->backlight_init_pending = false; > + > + return 0; > +} > +#else > +static int drm_panel_of_backlight_lazy(struct drm_panel *panel) { return 0; } > +#endif > + > /** > * drm_panel_init - initialize a panel > * @panel: DRM panel > @@ -161,6 +189,9 @@ int drm_panel_enable(struct drm_panel *panel) > return ret; > } > > + if (panel->backlight_init_pending) > + drm_panel_of_backlight_lazy(panel); > + > ret = backlight_enable(panel->backlight); > if (ret < 0) > DRM_DEV_INFO(panel->dev, "failed to enable backlight: %d\n", > @@ -187,6 +218,9 @@ int drm_panel_disable(struct drm_panel *panel) > if (!panel) > return -EINVAL; > > + if (panel->backlight_init_pending) > + drm_panel_of_backlight_lazy(panel); > + > ret = backlight_disable(panel->backlight); > if (ret < 0) > DRM_DEV_INFO(panel->dev, "failed to disable backlight: %d\n", > @@ -328,18 +362,7 @@ EXPORT_SYMBOL(of_drm_get_panel_orientation); > */ > int drm_panel_of_backlight(struct drm_panel *panel) > { > - struct backlight_device *backlight; > - > - if (!panel || !panel->dev) > - return -EINVAL; > - > - backlight = devm_of_find_backlight(panel->dev); > - > - if (IS_ERR(backlight)) > - return PTR_ERR(backlight); > - > - panel->backlight = backlight; > - return 0; > + return drm_panel_of_backlight_lazy(panel); Could you update the drm_panel_of_backlight() implementation (and do not forget the documentation) and avoid drm_panel_of_backlight_lazy()? Sam > } > EXPORT_SYMBOL(drm_panel_of_backlight); > #endif > diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h > index 33605c3f0eba..b126abebb2f3 100644 > --- a/include/drm/drm_panel.h > +++ b/include/drm/drm_panel.h > @@ -149,6 +149,14 @@ struct drm_panel { > */ > struct backlight_device *backlight; > > + /** > + * @backlight_init_pending > + * > + * Backlight driver is not yet available so further attempts to > + * initialize @backlight is necessary. > + */ > + bool backlight_init_pending; > + We have not done so today for other fields, but it would be good to document this is for drm_panel use only and drivers shall not touch. Sam _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
next prev parent reply other threads:[~2020-12-08 5:50 UTC|newest] Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-12-08 4:44 [RFC PATCH] drm/panel: Make backlight attachment lazy Bjorn Andersson 2020-12-08 4:44 ` Bjorn Andersson 2020-12-08 5:48 ` Sam Ravnborg [this message] 2020-12-08 5:48 ` Sam Ravnborg 2020-12-08 21:39 ` Bjorn Andersson 2020-12-08 21:39 ` Bjorn Andersson 2020-12-08 12:47 ` Thierry Reding 2020-12-08 12:47 ` Thierry Reding 2020-12-08 22:02 ` Bjorn Andersson 2020-12-08 22:02 ` Bjorn Andersson 2020-12-08 23:52 ` Daniel Vetter 2020-12-08 23:52 ` Daniel Vetter 2020-12-09 20:28 ` Bjorn Andersson 2020-12-09 20:28 ` Bjorn Andersson 2020-12-10 10:15 ` Daniel Vetter 2020-12-10 10:15 ` Daniel Vetter 2020-12-10 16:44 ` Thierry Reding 2020-12-10 16:44 ` Thierry Reding 2020-12-10 16:50 ` Daniel Vetter 2020-12-10 16:50 ` Daniel Vetter 2020-12-10 17:18 ` Thierry Reding 2020-12-10 17:18 ` Thierry Reding
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