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authorThierry Reding <treding@nvidia.com>2015-04-10 11:29:41 +0200
committerThierry Reding <treding@nvidia.com>2015-08-13 13:47:21 +0200
commit15372d4be7f099662dc84e4e35e844bd4373d959 (patch)
tree1654212589cad51d77aeb80bef21f5fe3c4c7b91 /drivers/gpu/host1x
parent5e7752436e10427ba598de4f2f6b7889daf586cc (diff)
downloadlinux-stericsson-15372d4be7f099662dc84e4e35e844bd4373d959.tar.gz
gpu: host1x: mipi: Power down regulators when unused
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>
Diffstat (limited to 'drivers/gpu/host1x')
-rw-r--r--drivers/gpu/host1x/mipi.c110
1 files changed, 98 insertions, 12 deletions
diff --git a/drivers/gpu/host1x/mipi.c b/drivers/gpu/host1x/mipi.c
index 0989b8151b4c..52a6fd224127 100644
--- a/drivers/gpu/host1x/mipi.c
+++ b/drivers/gpu/host1x/mipi.c
@@ -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);
}
@@ -227,23 +324,11 @@ 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);
value |= MIPI_CAL_BIAS_PAD_VCLAMP(soc->pad_vclamp_level);
@@ -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);