Messages in this thread | | | Subject | RE: [PATCH 1/2] [media] V4L: atmel-isi: add code toenable/disableISI_MCK clock | Date | Thu, 8 Dec 2011 11:18:23 +0800 | From | "Wu, Josh" <> |
| |
On Thursday, December 08, 2011 6:40AM, Russell King wrote:
> On Wed, Dec 07, 2011 at 06:12:52PM +0800, Wu, Josh wrote: >> Hi, Russell King >> >> On Wed, Dec 07, 2011 at 4:50 PM, Russell King wrote: >> >> > On Wed, Nov 30, 2011 at 06:06:43PM +0800, Josh Wu wrote: >> >> + /* Get ISI_MCK, provided by programmable clock or external clock >> */ >> >> + isi->mck = clk_get(dev, "isi_mck"); >> >> + if (IS_ERR_OR_NULL(isi->mck)) { >> >> > This should be IS_ERR() >> >> So it means the clk_get() will never return NULL even when clk structure >> is NULL in clk lookup entry. Right?
> It is not the drivers business to know whether NULL is valid or not.
> clk_get() is defined to either return an error pointer, or a cookie > which the rest of the clk API must accept.
> If an implementation decides that clk_get() can return NULL and deals > with that in the rest of the API (eg, to mean 'there is no clock but > don't fail for this') then drivers must not reject that.
> If a driver rejects NULL then it is performing checks outside of the > definition of the clk API, and making assumptions about the nature of > valid cookies.
Thanks for the feedback. I will send v3 patch which will not check the null return value.
Best Regards, Josh Wu
| |