If simple-card-utils accept NULL pointer on asoc_simple_card_xxx(),
each driver code will be more simple.
Let's accept NULL pointer.
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
 
 int asoc_simple_card_clk_enable(struct asoc_simple_dai *dai)
 {
-       return clk_prepare_enable(dai->clk);
+       if (dai)
+               return clk_prepare_enable(dai->clk);
+
+       return 0;
 }
 EXPORT_SYMBOL_GPL(asoc_simple_card_clk_enable);
 
 void asoc_simple_card_clk_disable(struct asoc_simple_dai *dai)
 {
-       clk_disable_unprepare(dai->clk);
+       if (dai)
+               clk_disable_unprepare(dai->clk);
 }
 EXPORT_SYMBOL_GPL(asoc_simple_card_clk_disable);
 
 {
        int ret;
 
+       if (!simple_dai)
+               return 0;
+
        if (simple_dai->sysclk) {
                ret = snd_soc_dai_set_sysclk(dai, 0, simple_dai->sysclk,
                                             simple_dai->clk_direction);