Re: [PATCH -next 12/25] spi: dw-mmio: Use helper function devm_clk_get_*()

Serge Semin
2023-08-22T13:46:42Z

Hi Li

On Tue, Aug 22, 2023 at 09:12:24PM +0800, Li Zetao wrote:
> Since commit 7ef9651e9792 ("clk: Provide new devm_clk helpers for prepared
> and enabled clocks"), devm_clk_get() and clk_prepare_enable() can now be
> replaced by devm_clk_get_enabled() when driver enables (and possibly
> prepares) the clocks for the whole lifetime of the device. Moreover, it is
> no longer necessary to unprepare and disable the clocks explicitly. Also,
> devm_clk_get_optional() and clk_prepare_enable() can now be replaced by
> devm_clk_get_optional_enabled(). Moreover, the lable "out_clk" no longer
> makes sense, rename it to "out_reset".
>
> Signed-off-by: Li Zetao <lizetao1@huawei.com>

Several nitpicks below please since you are touching the code anyway.

> ---
> drivers/spi/spi-dw-mmio.c | 20 +++++---------------
> 1 file changed, 5 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
> index 805264c9c65c..6d9f64ecbfd6 100644
> --- a/drivers/spi/spi-dw-mmio.c
> +++ b/drivers/spi/spi-dw-mmio.c
> @@ -340,28 +340,22 @@ static int dw_spi_mmio_probe(struct platform_device *pdev)
> if (dws->irq < 0)
> return dws->irq; /* -ENXIO */
>
> - dwsmmio->clk = devm_clk_get(&pdev->dev, NULL);
> + dwsmmio->clk = devm_clk_get_enabled(&pdev->dev, NULL);
> if (IS_ERR(dwsmmio->clk))
> return PTR_ERR(dwsmmio->clk);
> - ret = clk_prepare_enable(dwsmmio->clk);
> - if (ret)
> - return ret;
>
> /* Optional clock needed to access the registers */
> - dwsmmio->pclk = devm_clk_get_optional(&pdev->dev, "pclk");
> + dwsmmio->pclk = devm_clk_get_optional_enabled(&pdev->dev, "pclk");

> if (IS_ERR(dwsmmio->pclk)) {
> ret = PTR_ERR(dwsmmio->pclk);
> - goto out_clk;
> + goto out_reset;
> }

Just return from here please. There is no point in calling
reset_control_deassert() on error because the reset control handler
hasn't been requested yet. So the argument will be NULL and considered
as optional reset-control.

> - ret = clk_prepare_enable(dwsmmio->pclk);
> - if (ret)
> - goto out_clk;
>
> /* find an optional reset controller */
> dwsmmio->rstc = devm_reset_control_get_optional_exclusive(&pdev->dev, "spi");

> if (IS_ERR(dwsmmio->rstc)) {
> ret = PTR_ERR(dwsmmio->rstc);
> - goto out_clk;
> + goto out_reset;
> }

ditto

Please use the "out_reset" label in the next part of the code:
init_func = device_get_match_data(&pdev->dev);
if (init_func) {
ret = init_func(pdev, dwsmmio);
if (ret)
- goto out;
+ goto out_reset;
}

I know this changes the cleanup-on-error path logic. But since you are
touching exactly that code anyway it would be good to have it properly
fixed.

> reset_control_deassert(dwsmmio->rstc);
>
> @@ -397,9 +391,7 @@ static int dw_spi_mmio_probe(struct platform_device *pdev)
>
> out:
> pm_runtime_disable(&pdev->dev);
> - clk_disable_unprepare(dwsmmio->pclk);
> -out_clk:
> - clk_disable_unprepare(dwsmmio->clk);
> +out_reset:
> reset_control_assert(dwsmmio->rstc);
>
> return ret;
> @@ -411,8 +403,6 @@ static void dw_spi_mmio_remove(struct platform_device *pdev)
>

> dw_spi_remove_host(&dwsmmio->dws);
> pm_runtime_disable(&pdev->dev);
> - clk_disable_unprepare(dwsmmio->pclk);
> - clk_disable_unprepare(dwsmmio->clk);
> reset_control_assert(dwsmmio->rstc);

The order here isn't correct too. But I guess we can live with it.
It isn't that important.

-Serge(y)

> }
>
> --
> 2.34.1
>