drm/tegra: vic: Implement explicit reset support

Tegra supports generic PM domains on 64-bit ARM, and if that is enabled,
the power domain code will make sure that resets are asserted and
deasserted at appropriate points in time.

If generic PM domains are not implemented, such as on 32-bit Tegra, the
resets need to be asserted and deasserted explicitly by the driver.

Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

diff --git a/drivers/gpu/drm/tegra/vic.c b/drivers/gpu/drm/tegra/vic.c
index 9f657a63b0bb4a59943c436f3fece4efc460b074..396f29f289f525044d31e2776ca2c144a1c63f0c 100644 (file)
--- a/drivers/gpu/drm/tegra/vic.c
+++ b/drivers/gpu/drm/tegra/vic.c
@@ -38,6 +38,7 @@ struct vic {
        struct iommu_domain *domain;
        struct device *dev;
        struct clk *clk;
+       struct reset_control *rst;
 
        /* Platform configuration */
        const struct vic_config *config;
@@ -56,13 +57,37 @@ static void vic_writel(struct vic *vic, u32 value, unsigned int offset)
 static int vic_runtime_resume(struct device *dev)
 {
        struct vic *vic = dev_get_drvdata(dev);
+       int err;
+
+       err = clk_prepare_enable(vic->clk);
+       if (err < 0)
+               return err;
+
+       usleep_range(10, 20);
+
+       err = reset_control_deassert(vic->rst);
+       if (err < 0)
+               goto disable;
+
+       usleep_range(10, 20);
+
+       return 0;
 
-       return clk_prepare_enable(vic->clk);
+disable:
+       clk_disable_unprepare(vic->clk);
+       return err;
 }
 
 static int vic_runtime_suspend(struct device *dev)
 {
        struct vic *vic = dev_get_drvdata(dev);
+       int err;
+
+       err = reset_control_assert(vic->rst);
+       if (err < 0)
+               return err;
+
+       usleep_range(2000, 4000);
 
        clk_disable_unprepare(vic->clk);
 
@@ -323,6 +348,14 @@ static int vic_probe(struct platform_device *pdev)
                return PTR_ERR(vic->clk);
        }
 
+       if (!dev->pm_domain) {
+               vic->rst = devm_reset_control_get(dev, "vic");
+               if (IS_ERR(vic->rst)) {
+                       dev_err(&pdev->dev, "failed to get reset\n");
+                       return PTR_ERR(vic->rst);
+               }
+       }
+
        vic->falcon.dev = dev;
        vic->falcon.regs = vic->regs;
        vic->falcon.ops = &vic_falcon_ops;