linux-kernel - [PATCH] drm/omap: Migrate minimum FCK/PCK ratio from Kconfig to dts

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Message-Id: <20190510194229.20628-1-aford173@gmail.com>
Date:   Fri, 10 May 2019 14:42:29 -0500
From:   Adam Ford <aford173@...il.com>
To:     linux-omap@...r.kernel.org
Cc:     adam.ford@...icpd.com, Adam Ford <aford173@...il.com>,
        Tomi Valkeinen <tomi.valkeinen@...com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Benoît Cousson <bcousson@...libre.com>,
        Tony Lindgren <tony@...mide.com>,
        dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] drm/omap: Migrate minimum FCK/PCK ratio from Kconfig to dts

Currently the source code is compiled using hard-coded values
from CONFIG_OMAP2_DSS_MIN_FCK_PER_PCK.  This patch allows this
clock divider value to be moved to the device tree and be changed
without having to recompile the kernel.

Signed-off-by: Adam Ford <aford173@...il.com>

diff --git a/Documentation/devicetree/bindings/display/ti/ti,omap3-dss.txt b/Documentation/devicetree/bindings/display/ti/ti,omap3-dss.txt
index cd02516a40b6..42449d07c47e 100644
--- a/Documentation/devicetree/bindings/display/ti/ti,omap3-dss.txt
+++ b/Documentation/devicetree/bindings/display/ti/ti,omap3-dss.txt
@@ -40,7 +40,7 @@ Required properties:
 Optional properties:
 - max-memory-bandwidth: Input memory (from main memory to dispc) bandwidth limit
 			in bytes per second
-
+- min-fck-pck-ratio:  Make sure that DISPC FCK is at least n x PCK
 
 RFBI
 ----
diff --git a/arch/arm/boot/dts/omap3.dtsi b/arch/arm/boot/dts/omap3.dtsi
index 4043ecb38016..bf84a8487aae 100644
--- a/arch/arm/boot/dts/omap3.dtsi
+++ b/arch/arm/boot/dts/omap3.dtsi
@@ -751,7 +751,7 @@
 			#size-cells = <1>;
 			ranges;
 
-			dispc@...50400 {
+			dispc: dispc@...50400 {
 				compatible = "ti,omap3-dispc";
 				reg = <0x48050400 0x400>;
 				interrupts = <25>;
diff --git a/drivers/gpu/drm/omapdrm/dss/Kconfig b/drivers/gpu/drm/omapdrm/dss/Kconfig
index f24ebf7f61dd..d0666edcdf2a 100644
--- a/drivers/gpu/drm/omapdrm/dss/Kconfig
+++ b/drivers/gpu/drm/omapdrm/dss/Kconfig
@@ -102,24 +102,6 @@ config OMAP2_DSS_DSI
 
 	  See http://www.mipi.org/ for DSI specifications.
 
-config OMAP2_DSS_MIN_FCK_PER_PCK
-	int "Minimum FCK/PCK ratio (for scaling)"
-	range 0 32
-	default 0
-	help
-	  This can be used to adjust the minimum FCK/PCK ratio.
-
-	  With this you can make sure that DISPC FCK is at least
-	  n x PCK. Video plane scaling requires higher FCK than
-	  normally.
-
-	  If this is set to 0, there's no extra constraint on the
-	  DISPC FCK. However, the FCK will at minimum be
-	  2xPCK (if active matrix) or 3xPCK (if passive matrix).
-
-	  Max FCK is 173MHz, so this doesn't work if your PCK
-	  is very high.
-
 config OMAP2_DSS_SLEEP_AFTER_VENC_RESET
 	bool "Sleep 20ms after VENC reset"
 	default y
diff --git a/drivers/gpu/drm/omapdrm/dss/dispc.c b/drivers/gpu/drm/omapdrm/dss/dispc.c
index ba82d916719c..09a130c53da2 100644
--- a/drivers/gpu/drm/omapdrm/dss/dispc.c
+++ b/drivers/gpu/drm/omapdrm/dss/dispc.c
@@ -198,6 +198,9 @@ struct dispc_device {
 
 	/* DISPC_CONTROL & DISPC_CONFIG lock*/
 	spinlock_t control_lock;
+
+	/* Optional min-fck-pck-ratio */
+	u32 min_fck_per_pck;
 };
 
 enum omap_color_component {
@@ -3683,15 +3686,8 @@ bool dispc_div_calc(struct dispc_device *dispc, unsigned long dispc_freq,
 	unsigned long pck, lck;
 	unsigned long lck_max;
 	unsigned long pckd_hw_min, pckd_hw_max;
-	unsigned int min_fck_per_pck;
 	unsigned long fck;
 
-#ifdef CONFIG_OMAP2_DSS_MIN_FCK_PER_PCK
-	min_fck_per_pck = CONFIG_OMAP2_DSS_MIN_FCK_PER_PCK;
-#else
-	min_fck_per_pck = 0;
-#endif
-
 	pckd_hw_min = dispc->feat->min_pcd;
 	pckd_hw_max = 255;
 
@@ -3723,7 +3719,7 @@ bool dispc_div_calc(struct dispc_device *dispc, unsigned long dispc_freq,
 			else
 				fck = lck;
 
-			if (fck < pck * min_fck_per_pck)
+			if (fck < pck * dispc->min_fck_per_pck)
 				continue;
 
 			if (func(lckd, pckd, lck, pck, data))
@@ -4826,6 +4822,8 @@ static int dispc_bind(struct device *dev, struct device *master, void *data)
 		}
 	}
 
+	of_property_read_u32(np, "min-fck-pck-ratio", &dispc->min_fck_per_pck);
+
 	r = dispc_init_gamma_tables(dispc);
 	if (r)
 		goto err_free;
-- 
2.17.1