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From: Bjorn Andersson <bjorn.andersson@linaro.org>
To: Douglas Anderson <dianders@chromium.org>
Cc: Andrzej Hajda <a.hajda@samsung.com>,
	Neil Armstrong <narmstrong@baylibre.com>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	Jonas Karlman <jonas@kwiboo.se>,
	Jernej Skrabec <jernej.skrabec@siol.net>,
	Sam Ravnborg <sam@ravnborg.org>, Wolfram Sang <wsa@kernel.org>,
	Stephen Boyd <swboyd@chromium.org>,
	robdclark@chromium.org,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>,
	Steev Klimaszewski <steev@kali.org>,
	linux-arm-msm@vger.kernel.org, Linus W <linus.walleij@linaro.org>,
	Daniel Vetter <daniel@ffwll.ch>, David Airlie <airlied@linux.ie>,
	Thierry Reding <thierry.reding@gmail.com>,
	dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 16/27] drm/panel: panel-simple: Get rid of hacky HPD chicken-and-egg code
Date: Fri, 23 Apr 2021 09:50:47 -0500
Message-ID: <YILex5oaMUQy5zs/@builder.lan> (raw)
In-Reply-To: <20210416153909.v4.16.I40eeedc23459d1e3fc96fa6cdad775d88c6e706c@changeid>

On Fri 16 Apr 17:39 CDT 2021, Douglas Anderson wrote:

> When I added support for the hpd-gpio to simple-panel in commit
> 48834e6084f1 ("drm/panel-simple: Support hpd-gpios for delaying
> prepare()"), I added a special case to handle a circular dependency I
> was running into on the ti-sn65dsi86 bridge chip. On my board the
> hpd-gpio is actually provided by the bridge chip. That was causing
> some circular dependency problems that I had to work around by getting
> the hpd-gpio late.
> 
> I've now reorganized the ti-sn65dsi86 bridge chip driver to be a
> collection of sub-drivers. Now the GPIO part can probe separately and
> that breaks the chain. Let's get rid of the old code to clean things
> up.
> 

Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>

Regards,
Bjorn

> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---
> 
> (no changes since v1)
> 
>  drivers/gpu/drm/panel/panel-simple.c | 24 +++++-------------------
>  1 file changed, 5 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
> index 6b22872b3281..90a17ca79d06 100644
> --- a/drivers/gpu/drm/panel/panel-simple.c
> +++ b/drivers/gpu/drm/panel/panel-simple.c
> @@ -366,8 +366,7 @@ static int panel_simple_unprepare(struct drm_panel *panel)
>  	return 0;
>  }
>  
> -static int panel_simple_get_hpd_gpio(struct device *dev,
> -				     struct panel_simple *p, bool from_probe)
> +static int panel_simple_get_hpd_gpio(struct device *dev, struct panel_simple *p)
>  {
>  	int err;
>  
> @@ -375,17 +374,10 @@ static int panel_simple_get_hpd_gpio(struct device *dev,
>  	if (IS_ERR(p->hpd_gpio)) {
>  		err = PTR_ERR(p->hpd_gpio);
>  
> -		/*
> -		 * If we're called from probe we won't consider '-EPROBE_DEFER'
> -		 * to be an error--we'll leave the error code in "hpd_gpio".
> -		 * When we try to use it we'll try again.  This allows for
> -		 * circular dependencies where the component providing the
> -		 * hpd gpio needs the panel to init before probing.
> -		 */
> -		if (err != -EPROBE_DEFER || !from_probe) {
> +		if (err != -EPROBE_DEFER)
>  			dev_err(dev, "failed to get 'hpd' GPIO: %d\n", err);
> -			return err;
> -		}
> +
> +		return err;
>  	}
>  
>  	return 0;
> @@ -416,12 +408,6 @@ static int panel_simple_prepare_once(struct panel_simple *p)
>  		msleep(delay);
>  
>  	if (p->hpd_gpio) {
> -		if (IS_ERR(p->hpd_gpio)) {
> -			err = panel_simple_get_hpd_gpio(dev, p, false);
> -			if (err)
> -				goto error;
> -		}
> -
>  		if (p->desc->delay.hpd_absent_delay)
>  			hpd_wait_us = p->desc->delay.hpd_absent_delay * 1000UL;
>  		else
> @@ -682,7 +668,7 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
>  
>  	panel->no_hpd = of_property_read_bool(dev->of_node, "no-hpd");
>  	if (!panel->no_hpd) {
> -		err = panel_simple_get_hpd_gpio(dev, panel, true);
> +		err = panel_simple_get_hpd_gpio(dev, panel);
>  		if (err)
>  			return err;
>  	}
> -- 
> 2.31.1.368.gbe11c130af-goog
> 

  reply index

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-16 22:39 [PATCH v4 00/27] drm: Fix EDID reading on ti-sn65dsi86; solve some chicken-and-egg problems Douglas Anderson
2021-04-16 22:39 ` [PATCH v4 01/27] drm/bridge: Fix the stop condition of drm_bridge_chain_pre_enable() Douglas Anderson
2021-04-16 22:39 ` [PATCH v4 02/27] drm/bridge: ti-sn65dsi86: Simplify refclk handling Douglas Anderson
2021-04-16 22:39 ` [PATCH v4 03/27] drm/bridge: ti-sn65dsi86: Remove incorrectly tagged kerneldoc comment Douglas Anderson
2021-04-16 22:39 ` [PATCH v4 04/27] drm/bridge: ti-sn65dsi86: Reorder remove() Douglas Anderson
2021-04-16 22:39 ` [PATCH v4 05/27] drm/bridge: ti-sn65dsi86: Move drm_panel_unprepare() to post_disable() Douglas Anderson
2021-04-16 22:39 ` [PATCH v4 06/27] drm/bridge: ti-sn65dsi86: Get rid of the useless detect() function Douglas Anderson
2021-04-16 22:39 ` [PATCH v4 07/27] drm/panel: panel-simple: Use runtime pm to avoid excessive unprepare / prepare Douglas Anderson
2021-04-16 22:39 ` [PATCH v4 08/27] drm/bridge: ti-sn65dsi86: Rename the main driver data structure Douglas Anderson
2021-04-23 14:28   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 09/27] drm/bridge: ti-sn65dsi86: More renames in prep for sub-devices Douglas Anderson
2021-04-23 14:30   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 10/27] drm/bridge: ti-sn65dsi86: Clean debugfs code Douglas Anderson
2021-04-23 14:35   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 11/27] drm/bridge: ti-sn65dsi86: Add local var for "dev" to simplify probe Douglas Anderson
2021-04-23 14:38   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 12/27] drm/bridge: ti-sn65dsi86: Cleanup managing of drvdata Douglas Anderson
2021-04-23 14:38   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 13/27] drm/bridge: ti-sn65dsi86: Use devm to do our runtime_disable Douglas Anderson
2021-04-23 14:39   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 14/27] drm/bridge: ti-sn65dsi86: Move all the chip-related init to the start Douglas Anderson
2021-04-23 14:41   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 15/27] drm/bridge: ti-sn65dsi86: Break GPIO and MIPI-to-eDP bridge into sub-drivers Douglas Anderson
2021-04-23 14:49   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 16/27] drm/panel: panel-simple: Get rid of hacky HPD chicken-and-egg code Douglas Anderson
2021-04-23 14:50   ` Bjorn Andersson [this message]
2021-04-16 22:39 ` [PATCH v4 17/27] drm/bridge: ti-sn65dsi86: Use pm_runtime autosuspend Douglas Anderson
2021-04-23 14:51   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 18/27] drm/bridge: ti-sn65dsi86: Code motion of refclk management functions Douglas Anderson
2021-04-23 14:51   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 19/27] drm/bridge: ti-sn65dsi86: If refclk, DP AUX can happen w/out pre-enable Douglas Anderson
2021-04-23 14:56   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 20/27] drm/bridge: ti-sn65dsi86: Promote the AUX channel to its own sub-dev Douglas Anderson
2021-04-23 14:59   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 21/27] i2c: i2c-core-of: Fix corner case of finding adapter by node Douglas Anderson
2021-04-23 15:12   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 22/27] drm/panel: panel-simple: Remove extra call: drm_connector_update_edid_property() Douglas Anderson
2021-04-23 15:15   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 23/27] drm/panel: panel-simple: Power the panel when reading the EDID Douglas Anderson
2021-04-23 15:16   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 24/27] drm/panel: panel-simple: Cache the EDID as long as we retain power Douglas Anderson
2021-04-23 16:12   ` Bjorn Andersson
2021-04-23 16:30     ` Doug Anderson
2021-04-16 22:39 ` [PATCH v4 25/27] drm/bridge: ti-sn65dsi86: Don't read EDID blob over DDC Douglas Anderson
2021-04-23 16:13   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 26/27] arm64: dts: qcom: Link the panel to the bridge's DDC bus Douglas Anderson
2021-04-23 16:16   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 27/27] drm/panel: panel-simple: Prepare/unprepare are refcounted, not forced Douglas Anderson
2021-04-23 16:16   ` Bjorn Andersson
2021-04-23 16:46   ` Doug Anderson
2021-04-20 16:42 ` [PATCH v4 00/27] drm: Fix EDID reading on ti-sn65dsi86; solve some chicken-and-egg problems Doug Anderson

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