[PATCH 1/1] mtd:nand:fix memory leak

[Marc Gonzalez]

On 05/04/2018 11:54, Boris Brezillon wrote:

> On Thu, 5 Apr 2018 11:12:11 +0200, Marc Gonzalez wrote:
> 
>> I was not aware that clk_get() allocated memory, and required clk_put()
>> for cleanup. IIRC, I looked at Documentation/clk.txt
>>
>> On tango, clocks are configured by the boot loader. The existing clk driver
>> provides only read access to various clocks -- except the CPU clock, which
>> can be changed by tweaking a post-divider. Tweaking the PLLs requires much
>> more complex code. The boot loader enables every clock, and Linux has no
>> way to gate any of them.
> 
> Well, even if that's not supported today, it's always a good practice
> to retain reference and prepare/enable clks your HW depends on. This
> change should be harmless and when/if you someday decide to provide a
> way to gate clks, it will work out of the box.

IIUC, you're saying:
1) use devm_clk_get() instead of clk_get() to solve the memory leak
2) call clk_prepare_enable() before clk_get_rate() even if the former is a no-op today

The following patch implements these suggestions.
(Only compile-tested)

diff --git a/drivers/mtd/nand/tango_nand.c b/drivers/mtd/nand/tango_nand.c
index c5bee00b7f5e..39d190b7521f 100644
--- a/drivers/mtd/nand/tango_nand.c
+++ b/drivers/mtd/nand/tango_nand.c
@@ -643,7 +643,7 @@ static int tango_nand_probe(struct platform_device *pdev)
 
        writel_relaxed(MODE_RAW, nfc->pbus_base + PBUS_PAD_MODE);
 
-       clk = clk_get(&pdev->dev, NULL);
+       clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(clk))
                return PTR_ERR(clk);
 
@@ -651,6 +651,10 @@ static int tango_nand_probe(struct platform_device *pdev)
        if (IS_ERR(nfc->chan))
                return PTR_ERR(nfc->chan);
 
+       err = clk_prepare_enable(clk);
+       if (err)
+               return err;
+
        platform_set_drvdata(pdev, nfc);
        nand_hw_control_init(&nfc->hw);
        nfc->freq_kHz = clk_get_rate(clk) / 1000;