[bug report] ASoC: starfive: Add JH7110 TDM driver

[Dan Carpenter <dan.carpenter@xxxxxxxxxx>]

Hello Walker Chen,

The patch fd4762b6b5cf: "ASoC: starfive: Add JH7110 TDM driver" from
May 26, 2023, leads to the following Smatch static checker warning:

	sound/soc/starfive/jh7110_tdm.c:584 jh7110_tdm_clk_reset_get()
	warn: passing zero to 'PTR_ERR'

sound/soc/starfive/jh7110_tdm.c
    564 static int jh7110_tdm_clk_reset_get(struct platform_device *pdev,
    565                                     struct jh7110_tdm_dev *tdm)
    566 {
    567         int ret;
    568 
    569         tdm->clks[0].id = "mclk_inner";
    570         tdm->clks[1].id = "tdm_ahb";
    571         tdm->clks[2].id = "tdm_apb";
    572         tdm->clks[3].id = "tdm_internal";
    573         tdm->clks[4].id = "tdm_ext";
    574         tdm->clks[5].id = "tdm";
    575 
    576         ret = devm_clk_bulk_get(&pdev->dev, ARRAY_SIZE(tdm->clks), tdm->clks);
    577         if (ret) {
    578                 dev_err(&pdev->dev, "Failed to get tdm clocks\n");
    579                 return ret;
    580         }
    581 
    582         tdm->resets = devm_reset_control_array_get_exclusive(&pdev->dev);

The devm_reset_control_array_get() function returns NULL if it's
an optional request.  But this is not optional.

    583         if (IS_ERR_OR_NULL(tdm->resets)) {

So that means this should be an if (IS_ERR()) check.

--> 584                 ret = PTR_ERR(tdm->resets);
    585                 dev_err(&pdev->dev, "Failed to get tdm resets");

Or if optional was intended then NULL should not be treated as an error
case, but as a special kind of success case (no error message).  See
my blog for a long form of this information:

https://staticthinking.wordpress.com/2022/08/01/mixing-error-pointers-and-null/

    586                 return ret;
    587         }
    588 
    589         return 0;
    590 }

regards,
dan carpenter