On Fri, Jun 10, 2022 at 10:42:33AM +0300, Serge Semin wrote:
> Even though the DW I2C controller reference clock source is requested by
> the method devm_clk_get() with non-optional clock requirement the way the
> clock handler is used afterwards has a pure optional clock semantic
> (though in some circumstances we can get a warning about the clock missing
> printed in the system console). There is no point in reimplementing that
> functionality seeing the kernel clock framework already supports the
> optional interface from scratch. Thus let's convert the platform driver to
> using it.
>
> Note by providing this commit we get to fix two problems. The first one
> was introduced in commit c62ebb3d5f0d ("i2c: designware: Add support for
> an interface clock"). It causes not having the interface clock (pclk)
> enabled/disabled in case if the reference clock isn't provided. The second
> problem was first introduced in commit b33af11de236 ("i2c: designware: Do
> not require clock when SSCN and FFCN are provided"). Since that
> modification the deferred probe procedure has been unsupported in case if
> the interface clock isn't ready.
Makes sense,
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Fixes: c62ebb3d5f0d ("i2c: designware: Add support for an interface clock")
> Fixes: b33af11de236 ("i2c: designware: Do not require clock when SSCN and FFCN are provided")
> Signed-off-by: Serge Semin <Sergey.Semin@xxxxxxxxxxxxxxxxxxxx>
> ---
> drivers/i2c/busses/i2c-designware-common.c | 3 ---
> drivers/i2c/busses/i2c-designware-platdrv.c | 13 +++++++++++--
> 2 files changed, 11 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-designware-common.c b/drivers/i2c/busses/i2c-designware-common.c
> index 9f8574320eb2..b08e5bc2b64c 100644
> --- a/drivers/i2c/busses/i2c-designware-common.c
> +++ b/drivers/i2c/busses/i2c-designware-common.c
> @@ -477,9 +477,6 @@ int i2c_dw_prepare_clk(struct dw_i2c_dev *dev, bool prepare)
> {
> int ret;
>
> - if (IS_ERR(dev->clk))
> - return PTR_ERR(dev->clk);
> -
> if (prepare) {
> /* Optional interface clock */
> ret = clk_prepare_enable(dev->pclk);
> diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
> index 70ade5306e45..ba043b547393 100644
> --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> @@ -320,8 +320,17 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
> goto exit_reset;
> }
>
> - dev->clk = devm_clk_get(&pdev->dev, NULL);
> - if (!i2c_dw_prepare_clk(dev, true)) {
> + dev->clk = devm_clk_get_optional(&pdev->dev, NULL);
> + if (IS_ERR(dev->clk)) {
> + ret = PTR_ERR(dev->clk);
> + goto exit_reset;
> + }
> +
> + ret = i2c_dw_prepare_clk(dev, true);
> + if (ret)
> + goto exit_reset;
> +
> + if (dev->clk) {
> u64 clk_khz;
>
> dev->get_clk_rate_khz = i2c_dw_get_clk_rate_khz;
> --
> 2.35.1
>
--
With Best Regards,
Andy Shevchenko
