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From 09c1533f7f5dabd79aa2018083d1b71d26cd7eda Mon Sep 17 00:00:00 2001
From: Naushir Patuck <naush@raspberrypi.com>
Date: Mon, 11 May 2020 13:02:22 +0100
Subject: [PATCH] media: bcm2835: unicam: Set VPU min clock freq to
 250Mhz.

When streaming with Unicam, the VPU must have a clock frequency of at
least 250Mhz.  Otherwise, the input fifos could overrun, causing
image corruption.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
---
 arch/arm/boot/dts/bcm270x.dtsi                | 10 ++--
 .../media/platform/bcm2835/bcm2835-unicam.c   | 49 +++++++++++++++++--
 2 files changed, 50 insertions(+), 9 deletions(-)

--- a/arch/arm/boot/dts/bcm270x.dtsi
+++ b/arch/arm/boot/dts/bcm270x.dtsi
@@ -88,8 +88,9 @@
                        reg = <0x7e800000 0x800>,
                              <0x7e802000 0x4>;
                        interrupts = <2 6>;
-                       clocks = <&clocks BCM2835_CLOCK_CAM0>;
-                       clock-names = "lp";
+                       clocks = <&clocks BCM2835_CLOCK_CAM0>,
+                                <&firmware_clocks 4>;
+                       clock-names = "lp", "vpu";
                        power-domains = <&power RPI_POWER_DOMAIN_UNICAM0>;
                        #address-cells = <1>;
                        #size-cells = <0>;
@@ -102,8 +103,9 @@
                        reg = <0x7e801000 0x800>,
                              <0x7e802004 0x4>;
                        interrupts = <2 7>;
-                       clocks = <&clocks BCM2835_CLOCK_CAM1>;
-                       clock-names = "lp";
+                       clocks = <&clocks BCM2835_CLOCK_CAM1>,
+                                <&firmware_clocks 4>;
+                       clock-names = "lp", "vpu";
                        power-domains = <&power RPI_POWER_DOMAIN_UNICAM1>;
                        #address-cells = <1>;
                        #size-cells = <0>;
--- a/drivers/media/platform/bcm2835/bcm2835-unicam.c
+++ b/drivers/media/platform/bcm2835/bcm2835-unicam.c
@@ -89,6 +89,11 @@ MODULE_PARM_DESC(debug, "Debug level 0-3
                v4l2_err(&(dev)->v4l2_dev, fmt, ##arg)
 
 /*
+ * Unicam must request a minimum of 250Mhz from the VPU clock.
+ * Otherwise the input FIFOs overrun and cause image corruption.
+ */
+#define MIN_VPU_CLOCK_RATE (250 * 1000 * 1000)
+/*
  * To protect against a dodgy sensor driver never returning an error from
  * enum_mbus_code, set a maximum index value to be used.
  */
@@ -417,8 +422,10 @@ struct unicam_device {
        void __iomem *base;
        /* clock gating base address */
        void __iomem *clk_gate_base;
-       /* clock handle */
+       /* lp clock handle */
        struct clk *clock;
+       /* vpu clock handle */
+       struct clk *vpu_clock;
        /* V4l2 device */
        struct v4l2_device v4l2_dev;
        struct media_device mdev;
@@ -1674,16 +1681,28 @@ static int unicam_start_streaming(struct
        unicam_dbg(1, dev, "Running with %u data lanes\n",
                   dev->active_data_lanes);
 
-       ret = clk_set_rate(dev->clock, 100 * 1000 * 1000);
+       ret = clk_set_min_rate(dev->vpu_clock, MIN_VPU_CLOCK_RATE);
+       if (ret) {
+               unicam_err(dev, "failed to set up VPU clock\n");
+               goto err_pm_put;
+       }
+
+       ret = clk_prepare_enable(dev->vpu_clock);
        if (ret) {
-               unicam_err(dev, "failed to set up clock\n");
+               unicam_err(dev, "Failed to enable VPU clock: %d\n", ret);
                goto err_pm_put;
        }
 
+       ret = clk_set_rate(dev->clock, 100 * 1000 * 1000);
+       if (ret) {
+               unicam_err(dev, "failed to set up CSI clock\n");
+               goto err_vpu_clock;
+       }
+
        ret = clk_prepare_enable(dev->clock);
        if (ret) {
                unicam_err(dev, "Failed to enable CSI clock: %d\n", ret);
-               goto err_pm_put;
+               goto err_vpu_clock;
        }
 
        for (i = 0; i < ARRAY_SIZE(dev->node); i++) {
@@ -1717,6 +1736,11 @@ static int unicam_start_streaming(struct
 err_disable_unicam:
        unicam_disable(dev);
        clk_disable_unprepare(dev->clock);
+err_vpu_clock:
+       ret = clk_set_min_rate(dev->vpu_clock, 0);
+       if (ret)
+               unicam_err(dev, "failed to reset the VPU clock\n");
+       clk_disable_unprepare(dev->vpu_clock);
 err_pm_put:
        unicam_runtime_put(dev);
 err_streaming:
@@ -1734,6 +1758,8 @@ static void unicam_stop_streaming(struct
        node->streaming = false;
 
        if (node->pad_id == IMAGE_PAD) {
+               int ret;
+
                /*
                 * Stop streaming the sensor and disable the peripheral.
                 * We cannot continue streaming embedded data with the
@@ -1743,6 +1769,12 @@ static void unicam_stop_streaming(struct
                        unicam_err(dev, "stream off failed in subdev\n");
 
                unicam_disable(dev);
+
+               ret = clk_set_min_rate(dev->vpu_clock, 0);
+               if (ret)
+                       unicam_err(dev, "failed to reset the min VPU clock\n");
+
+               clk_disable_unprepare(dev->vpu_clock);
                clk_disable_unprepare(dev->clock);
                unicam_runtime_put(dev);
 
@@ -2742,11 +2774,18 @@ static int unicam_probe(struct platform_
 
        unicam->clock = devm_clk_get(&pdev->dev, "lp");
        if (IS_ERR(unicam->clock)) {
-               unicam_err(unicam, "Failed to get clock\n");
+               unicam_err(unicam, "Failed to get lp clock\n");
                ret = PTR_ERR(unicam->clock);
                goto err_unicam_put;
        }
 
+       unicam->vpu_clock = devm_clk_get(&pdev->dev, "vpu");
+       if (IS_ERR(unicam->vpu_clock)) {
+               unicam_err(unicam, "Failed to get vpu clock\n");
+               ret = PTR_ERR(unicam->vpu_clock);
+               goto err_unicam_put;
+       }
+
        ret = platform_get_irq(pdev, 0);
        if (ret <= 0) {
                dev_err(&pdev->dev, "No IRQ resource\n");