Re: [PATCH V1] ASoC: fsl_ssi: refine ipg clock usage in this module

On Tue, Sep 09, 2014 at 03:03:53PM -0500, Timur Tabi wrote:

On 09/09/2014 02:59 PM, Nicolin Chen wrote:

quoted

+	/*
+	 * Initially mark the clock to NULL for all platforms so that later
+	 * clk_prepare_enable() will ignore and return 0 for non-clock cases.
+	 */
+	ssi_private->clk = NULL;

According to Mark, NULL is a valid clock, so this should be instead:

	ssi_private->clk = PTR_ERR(-EINVAL);

although that doesn't sit well with me.

I guess Mark's comment is merely against the check for clk validation
because if talking about clk validation, we should check IS_ERR(clk)
rather than check !=NULL directly.

However, my approach doesn't need any check. The open() or pm_resume()
can just call clk_prepare_enable() directly. The __clk_enable() will
then handle the 'clk == NULL' case:

static int __clk_enable(struct clk *clk)
{
	int ret = 0;

	if (!clk)
		return 0;