Nouveau - Apr 2016 - [PATCH] tegra: acquire and enable reference clock if needed

GM20B requires an extra clock compared to GK20A. Add that information
into the platform data and acquire and enable this clock if necessary.

Signed-off-by: Alexandre Courbot <acourbot at nvidia.com>
---
Hi Ben,

The DT bindings for this have been approved but not merged yet. This means
that for 4.6 GM20B will fail to probe unless the DT is patched - but this
is better than the current situation where it silently freezes. Can you
take this for the next -rc? Thanks!

 drm/nouveau/include/nvkm/core/tegra.h  |  5 +++++
 drm/nouveau/nouveau_platform.c         |  7 ++++++-
 drm/nouveau/nvkm/engine/device/tegra.c | 17 +++++++++++++++++
 3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/drm/nouveau/include/nvkm/core/tegra.h
b/drm/nouveau/include/nvkm/core/tegra.h
index 16641cec18a2..b5370cb56e3c 100644
--- a/drm/nouveau/include/nvkm/core/tegra.h
+++ b/drm/nouveau/include/nvkm/core/tegra.h
@@ -11,6 +11,7 @@ struct nvkm_device_tegra {
 
 	struct reset_control *rst;
 	struct clk *clk;
+	struct clk *clk_ref;
 	struct clk *clk_pwr;
 
 	struct regulator *vdd;
@@ -36,6 +37,10 @@ struct nvkm_device_tegra_func {
 	 * bypassed). A value of 0 means an IOMMU is never used.
 	 */
 	u8 iommu_bit;
+	/*
+	 * Whether the chip requires a reference clock
+	 */
+	bool require_ref_clk;
 };
 
 int nvkm_device_tegra_new(const struct nvkm_device_tegra_func *,
diff --git a/drm/nouveau/nouveau_platform.c b/drm/nouveau/nouveau_platform.c
index 2dfe58af12e4..4c4cc2260257 100644
--- a/drm/nouveau/nouveau_platform.c
+++ b/drm/nouveau/nouveau_platform.c
@@ -55,6 +55,11 @@ static const struct nvkm_device_tegra_func
gk20a_platform_data = {
 	.iommu_bit = 34,
 };
 
+static const struct nvkm_device_tegra_func gm20b_platform_data = {
+	.iommu_bit = 34,
+	.require_ref_clk = true,
+};
+
 static const struct of_device_id nouveau_platform_match[] = {
 	{
 		.compatible = "nvidia,gk20a",
@@ -62,7 +67,7 @@ static const struct of_device_id nouveau_platform_match[] = {
 	},
 	{
 		.compatible = "nvidia,gm20b",
-		.data = &gk20a_platform_data,
+		.data = &gm20b_platform_data,
 	},
 	{ }
 };
diff --git a/drm/nouveau/nvkm/engine/device/tegra.c
b/drm/nouveau/nvkm/engine/device/tegra.c
index 9afa5f3e3c1c..ec12efb4689a 100644
--- a/drm/nouveau/nvkm/engine/device/tegra.c
+++ b/drm/nouveau/nvkm/engine/device/tegra.c
@@ -35,6 +35,11 @@ nvkm_device_tegra_power_up(struct nvkm_device_tegra *tdev)
 	ret = clk_prepare_enable(tdev->clk);
 	if (ret)
 		goto err_clk;
+	if (tdev->clk_ref) {
+		ret = clk_prepare_enable(tdev->clk_ref);
+		if (ret)
+			goto err_clk_ref;
+	}
 	ret = clk_prepare_enable(tdev->clk_pwr);
 	if (ret)
 		goto err_clk_pwr;
@@ -57,6 +62,9 @@ nvkm_device_tegra_power_up(struct nvkm_device_tegra *tdev)
 err_clamp:
 	clk_disable_unprepare(tdev->clk_pwr);
 err_clk_pwr:
+	if (tdev->clk_ref)
+		clk_disable_unprepare(tdev->clk_ref);
+err_clk_ref:
 	clk_disable_unprepare(tdev->clk);
 err_clk:
 	regulator_disable(tdev->vdd);
@@ -71,6 +79,8 @@ nvkm_device_tegra_power_down(struct nvkm_device_tegra *tdev)
 	udelay(10);
 
 	clk_disable_unprepare(tdev->clk_pwr);
+	if (tdev->clk_ref)
+		clk_disable_unprepare(tdev->clk_ref);
 	clk_disable_unprepare(tdev->clk);
 	udelay(10);
 
@@ -274,6 +284,13 @@ nvkm_device_tegra_new(const struct nvkm_device_tegra_func
*func,
 		goto free;
 	}
 
+	if (func->require_ref_clk)
+		tdev->clk_ref = devm_clk_get(&pdev->dev, "ref");
+	if (IS_ERR(tdev->clk_ref)) {
+		ret = PTR_ERR(tdev->clk_ref);
+		goto free;
+	}
+
 	tdev->clk_pwr = devm_clk_get(&pdev->dev, "pwr");
 	if (IS_ERR(tdev->clk_pwr)) {
 		ret = PTR_ERR(tdev->clk_pwr);
-- 
2.7.3

On Fri, Apr 01, 2016 at 11:37:44AM +0900, Alexandre Courbot
wrote:
> GM20B requires an extra clock compared to GK20A. Add that information
> into the platform data and acquire and enable this clock if necessary.
> 
> Signed-off-by: Alexandre Courbot <acourbot at nvidia.com>
> ---
> Hi Ben,
> 
> The DT bindings for this have been approved but not merged yet. This means
> that for 4.6 GM20B will fail to probe unless the DT is patched - but this
> is better than the current situation where it silently freezes. Can you
> take this for the next -rc? Thanks!
> 
>  drm/nouveau/include/nvkm/core/tegra.h  |  5 +++++
>  drm/nouveau/nouveau_platform.c         |  7 ++++++-
>  drm/nouveau/nvkm/engine/device/tegra.c | 17 +++++++++++++++++
>  3 files changed, 28 insertions(+), 1 deletion(-)
Yes, this looks like the proper fix for Tegra210:

Reviewed-by: Thierry Reding <treding at nvidia.com>
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