[PATCH] clk: tegra: dfll: Fix drvdata overwriting issue

From: Nicolin Chen
Date: Thu Oct 12 2017 - 19:10:06 EST


Both tegra124-dfll and clk-dfll are using platform_set_drvdata
to set drvdata of the exact same pdev while they use different
pointers for the drvdata. Once the drvdata has been overwritten
by tegra124-dfll, clk-dfll will never get its td pointer as it
expects.

Since tegra124-dfll merely needs its soc pointer in its remove
function, this patch fixes the bug by removing the overwriting
in the tegra124-dfll file and letting the tegra_dfll_unregister
return an soc pointer for it.

Signed-off-by: Nicolin Chen <nicoleotsuka@xxxxxxxxx>
---

As I don't have a T124 platform, I can't verify it on a board.
If someone could provide a Tested-by, it would be very helpful.
The test could be a simple system suspend/resume that activates
runtime_suspend/resume() where a platform_get_drvdata() would
be called. -- Nicolin

drivers/clk/tegra/clk-dfll.c | 10 +++++-----
drivers/clk/tegra/clk-dfll.h | 2 +-
drivers/clk/tegra/clk-tegra124-dfll-fcpu.c | 12 +++++-------
3 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/drivers/clk/tegra/clk-dfll.c b/drivers/clk/tegra/clk-dfll.c
index 2c44aeb..0a7deee 100644
--- a/drivers/clk/tegra/clk-dfll.c
+++ b/drivers/clk/tegra/clk-dfll.c
@@ -1728,10 +1728,10 @@ EXPORT_SYMBOL(tegra_dfll_register);
* @pdev: DFLL platform_device *
*
* Unbind this driver from the DFLL hardware device represented by
- * @pdev. The DFLL must be disabled for this to succeed. Returns 0
- * upon success or -EBUSY if the DFLL is still active.
+ * @pdev. The DFLL must be disabled for this to succeed. Returns a
+ * soc pointer upon success or -EBUSY if the DFLL is still active.
*/
-int tegra_dfll_unregister(struct platform_device *pdev)
+struct tegra_dfll_soc_data *tegra_dfll_unregister(struct platform_device *pdev)
{
struct tegra_dfll *td = platform_get_drvdata(pdev);

@@ -1739,7 +1739,7 @@ int tegra_dfll_unregister(struct platform_device *pdev)
if (td->mode != DFLL_DISABLED) {
dev_err(&pdev->dev,
"must disable DFLL before removing driver\n");
- return -EBUSY;
+ return ERR_PTR(-EBUSY);
}

debugfs_remove_recursive(td->debugfs_dir);
@@ -1753,6 +1753,6 @@ int tegra_dfll_unregister(struct platform_device *pdev)

reset_control_assert(td->dvco_rst);

- return 0;
+ return td->soc;
}
EXPORT_SYMBOL(tegra_dfll_unregister);
diff --git a/drivers/clk/tegra/clk-dfll.h b/drivers/clk/tegra/clk-dfll.h
index ed2ad88..83352c8 100644
--- a/drivers/clk/tegra/clk-dfll.h
+++ b/drivers/clk/tegra/clk-dfll.h
@@ -43,7 +43,7 @@ struct tegra_dfll_soc_data {

int tegra_dfll_register(struct platform_device *pdev,
struct tegra_dfll_soc_data *soc);
-int tegra_dfll_unregister(struct platform_device *pdev);
+struct tegra_dfll_soc_data *tegra_dfll_unregister(struct platform_device *pdev);
int tegra_dfll_runtime_suspend(struct device *dev);
int tegra_dfll_runtime_resume(struct device *dev);

diff --git a/drivers/clk/tegra/clk-tegra124-dfll-fcpu.c b/drivers/clk/tegra/clk-tegra124-dfll-fcpu.c
index ad1c1cc..269d359 100644
--- a/drivers/clk/tegra/clk-tegra124-dfll-fcpu.c
+++ b/drivers/clk/tegra/clk-tegra124-dfll-fcpu.c
@@ -125,19 +125,17 @@ static int tegra124_dfll_fcpu_probe(struct platform_device *pdev)
return err;
}

- platform_set_drvdata(pdev, soc);
-
return 0;
}

static int tegra124_dfll_fcpu_remove(struct platform_device *pdev)
{
- struct tegra_dfll_soc_data *soc = platform_get_drvdata(pdev);
- int err;
+ struct tegra_dfll_soc_data *soc;

- err = tegra_dfll_unregister(pdev);
- if (err < 0)
- dev_err(&pdev->dev, "failed to unregister DFLL: %d\n", err);
+ soc = tegra_dfll_unregister(pdev);
+ if (IS_ERR(soc))
+ dev_err(&pdev->dev, "failed to unregister DFLL: %ld\n",
+ PTR_ERR(soc));

tegra_cvb_remove_opp_table(soc->dev, soc->cvb, soc->max_freq);

--
2.1.4