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authorThierry Reding <treding@nvidia.com>2016-08-12 16:00:53 +0200
committerThierry Reding <treding@nvidia.com>2016-08-24 15:58:57 +0200
commit87904c3e82319cf2bad8d656d79c5030dab9490e (patch)
tree63c0c4e6f0e89cb53e064b1839b59591df94b741 /drivers/gpu/host1x
parent29b4817d4018df78086157ea3a55c1d9424a7cfc (diff)
downloadlinux-87904c3e82319cf2bad8d656d79c5030dab9490e.tar.bz2
drm/tegra: dsi: Enhance runtime power management
The MIPI DSI output on Tegra SoCs requires some external logic to calibrate the MIPI pads before a video signal can be transmitted. This MIPI calibration logic requires to be powered on while the MIPI pads are being used, which is currently done as part of the DSI driver's probe implementation. This is suboptimal because it will leave the MIPI calibration logic powered up even if the DSI output is never used. On Tegra114 and earlier this behaviour also causes the driver to hang while trying to power up the MIPI calibration logic because the power partition that contains the MIPI calibration logic will be powered on by the display controller at output pipeline configuration time. Thus the power up sequence for the MIPI calibration logic happens before it's power partition is guaranteed to be enabled. Fix this by splitting up the API into a request/free pair of functions that manage the runtime dependency between the DSI and the calibration modules (no registers are accessed) and a set of enable, calibrate and disable functions that program the MIPI calibration logic at points in time where the power partition is really enabled. While at it, make sure that the runtime power management also works in ganged mode, which is currently also broken. Reported-by: Jonathan Hunter <jonathanh@nvidia.com> Tested-by: Jonathan Hunter <jonathanh@nvidia.com> Signed-off-by: Thierry Reding <treding@nvidia.com>
Diffstat (limited to 'drivers/gpu/host1x')
-rw-r--r--drivers/gpu/host1x/mipi.c63
1 files changed, 31 insertions, 32 deletions
diff --git a/drivers/gpu/host1x/mipi.c b/drivers/gpu/host1x/mipi.c
index 52a6fd224127..e00809d996a2 100644
--- a/drivers/gpu/host1x/mipi.c
+++ b/drivers/gpu/host1x/mipi.c
@@ -242,20 +242,6 @@ 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:
@@ -270,29 +256,42 @@ EXPORT_SYMBOL(tegra_mipi_request);
void tegra_mipi_free(struct tegra_mipi_device *device)
{
- int err;
+ platform_device_put(device->pdev);
+ kfree(device);
+}
+EXPORT_SYMBOL(tegra_mipi_free);
- mutex_lock(&device->mipi->lock);
+int tegra_mipi_enable(struct tegra_mipi_device *dev)
+{
+ int err = 0;
- 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_lock(&dev->mipi->lock);
- mutex_unlock(&device->mipi->lock);
+ if (dev->mipi->usage_count++ == 0)
+ err = tegra_mipi_power_up(dev->mipi);
+
+ mutex_unlock(&dev->mipi->lock);
+
+ return err;
- platform_device_put(device->pdev);
- kfree(device);
}
-EXPORT_SYMBOL(tegra_mipi_free);
+EXPORT_SYMBOL(tegra_mipi_enable);
+
+int tegra_mipi_disable(struct tegra_mipi_device *dev)
+{
+ int err = 0;
+
+ mutex_lock(&dev->mipi->lock);
+
+ if (--dev->mipi->usage_count == 0)
+ err = tegra_mipi_power_down(dev->mipi);
+
+ mutex_unlock(&dev->mipi->lock);
+
+ return err;
+
+}
+EXPORT_SYMBOL(tegra_mipi_disable);
static int tegra_mipi_wait(struct tegra_mipi *mipi)
{