gpu: host1x: mipi: Power down regulators when unused
authorThierry Reding <treding@nvidia.com>
Fri, 10 Apr 2015 09:29:41 +0000 (11:29 +0200)
committerThierry Reding <treding@nvidia.com>
Thu, 13 Aug 2015 11:47:21 +0000 (13:47 +0200)
Keep track of the number of users of DSI and CSI pads and power down the
regulators that supply the bricks when all users are gone.

Signed-off-by: Thierry Reding <treding@nvidia.com>
drivers/gpu/host1x/mipi.c

index 0989b8151b4cd9775d84a30748a6a8fdfa6e7601..52a6fd224127ef113f2d23338a46d10df28e955e 100644 (file)
@@ -118,9 +118,12 @@ struct tegra_mipi_soc {
 
 struct tegra_mipi {
        const struct tegra_mipi_soc *soc;
+       struct device *dev;
        void __iomem *regs;
        struct mutex lock;
        struct clk *clk;
+
+       unsigned long usage_count;
 };
 
 struct tegra_mipi_device {
@@ -142,6 +145,67 @@ static inline void tegra_mipi_writel(struct tegra_mipi *mipi, u32 value,
        writel(value, mipi->regs + (offset << 2));
 }
 
+static int tegra_mipi_power_up(struct tegra_mipi *mipi)
+{
+       u32 value;
+       int err;
+
+       err = clk_enable(mipi->clk);
+       if (err < 0)
+               return err;
+
+       value = tegra_mipi_readl(mipi, MIPI_CAL_BIAS_PAD_CFG0);
+       value &= ~MIPI_CAL_BIAS_PAD_PDVCLAMP;
+
+       if (mipi->soc->needs_vclamp_ref)
+               value |= MIPI_CAL_BIAS_PAD_E_VCLAMP_REF;
+
+       tegra_mipi_writel(mipi, value, MIPI_CAL_BIAS_PAD_CFG0);
+
+       value = tegra_mipi_readl(mipi, MIPI_CAL_BIAS_PAD_CFG2);
+       value &= ~MIPI_CAL_BIAS_PAD_PDVREG;
+       tegra_mipi_writel(mipi, value, MIPI_CAL_BIAS_PAD_CFG2);
+
+       clk_disable(mipi->clk);
+
+       return 0;
+}
+
+static int tegra_mipi_power_down(struct tegra_mipi *mipi)
+{
+       u32 value;
+       int err;
+
+       err = clk_enable(mipi->clk);
+       if (err < 0)
+               return err;
+
+       /*
+        * The MIPI_CAL_BIAS_PAD_PDVREG controls a voltage regulator that
+        * supplies the DSI pads. This must be kept enabled until none of the
+        * DSI lanes are used anymore.
+        */
+       value = tegra_mipi_readl(mipi, MIPI_CAL_BIAS_PAD_CFG2);
+       value |= MIPI_CAL_BIAS_PAD_PDVREG;
+       tegra_mipi_writel(mipi, value, MIPI_CAL_BIAS_PAD_CFG2);
+
+       /*
+        * MIPI_CAL_BIAS_PAD_PDVCLAMP and MIPI_CAL_BIAS_PAD_E_VCLAMP_REF
+        * control a regulator that supplies current to the pre-driver logic.
+        * Powering down this regulator causes DSI to fail, so it must remain
+        * powered on until none of the DSI lanes are used anymore.
+        */
+       value = tegra_mipi_readl(mipi, MIPI_CAL_BIAS_PAD_CFG0);
+
+       if (mipi->soc->needs_vclamp_ref)
+               value &= ~MIPI_CAL_BIAS_PAD_E_VCLAMP_REF;
+
+       value |= MIPI_CAL_BIAS_PAD_PDVCLAMP;
+       tegra_mipi_writel(mipi, value, MIPI_CAL_BIAS_PAD_CFG0);
+
+       return 0;
+}
+
 struct tegra_mipi_device *tegra_mipi_request(struct device *device)
 {
        struct device_node *np = device->of_node;
@@ -178,6 +242,20 @@ struct tegra_mipi_device *tegra_mipi_request(struct device *device)
        dev->pads = args.args[0];
        dev->device = device;
 
+       mutex_lock(&dev->mipi->lock);
+
+       if (dev->mipi->usage_count++ == 0) {
+               err = tegra_mipi_power_up(dev->mipi);
+               if (err < 0) {
+                       dev_err(dev->mipi->dev,
+                               "failed to power up MIPI bricks: %d\n",
+                               err);
+                       return ERR_PTR(err);
+               }
+       }
+
+       mutex_unlock(&dev->mipi->lock);
+
        return dev;
 
 put:
@@ -192,6 +270,25 @@ EXPORT_SYMBOL(tegra_mipi_request);
 
 void tegra_mipi_free(struct tegra_mipi_device *device)
 {
+       int err;
+
+       mutex_lock(&device->mipi->lock);
+
+       if (--device->mipi->usage_count == 0) {
+               err = tegra_mipi_power_down(device->mipi);
+               if (err < 0) {
+                       /*
+                        * Not much that can be done here, so an error message
+                        * will have to do.
+                        */
+                       dev_err(device->mipi->dev,
+                               "failed to power down MIPI bricks: %d\n",
+                               err);
+               }
+       }
+
+       mutex_unlock(&device->mipi->lock);
+
        platform_device_put(device->pdev);
        kfree(device);
 }
@@ -227,22 +324,10 @@ int tegra_mipi_calibrate(struct tegra_mipi_device *device)
 
        mutex_lock(&device->mipi->lock);
 
-       value = tegra_mipi_readl(device->mipi, MIPI_CAL_BIAS_PAD_CFG0);
-       value &= ~MIPI_CAL_BIAS_PAD_PDVCLAMP;
-
-       if (soc->needs_vclamp_ref)
-               value |= MIPI_CAL_BIAS_PAD_E_VCLAMP_REF;
-
-       tegra_mipi_writel(device->mipi, value, MIPI_CAL_BIAS_PAD_CFG0);
-
        value = MIPI_CAL_BIAS_PAD_DRV_DN_REF(soc->pad_drive_down_ref) |
                MIPI_CAL_BIAS_PAD_DRV_UP_REF(soc->pad_drive_up_ref);
        tegra_mipi_writel(device->mipi, value, MIPI_CAL_BIAS_PAD_CFG1);
 
-       value = tegra_mipi_readl(device->mipi, MIPI_CAL_BIAS_PAD_CFG2);
-       value &= ~MIPI_CAL_BIAS_PAD_PDVREG;
-       tegra_mipi_writel(device->mipi, value, MIPI_CAL_BIAS_PAD_CFG2);
-
        value = tegra_mipi_readl(device->mipi, MIPI_CAL_BIAS_PAD_CFG2);
        value &= ~MIPI_CAL_BIAS_PAD_VCLAMP(0x7);
        value &= ~MIPI_CAL_BIAS_PAD_VAUXP(0x7);
@@ -426,6 +511,7 @@ static int tegra_mipi_probe(struct platform_device *pdev)
                return -ENOMEM;
 
        mipi->soc = match->data;
+       mipi->dev = &pdev->dev;
 
        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        mipi->regs = devm_ioremap_resource(&pdev->dev, res);