ssbi: Comment the use of udelay() (3f7a73b5) · Commits · 戴 / test

The ssbi driver uses a busywait loop to read its status register. Add a comment explaining the timing of the device itself so that future developers can better understand this delay, and possibly diagnose any problems. Signed-off-by:

David Brown <davidb@codeaurora.org> Signed-off-by:

Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/ssbi/ssbi.c

+13 −0

Original line number	Diff line number	Diff line
		@@ -87,6 +87,15 @@ static inline void ssbi_writel(struct msm_ssbi *ssbi, u32 val, u32 reg)
		writel(val, ssbi->base + reg);
		}

		/*
		* Via private exchange with one of the original authors, the hardware
		* should generally finish a transaction in about 5us. The worst
		* case, is when using the arbiter and both other CPUs have just
		* started trying to use the SSBI bus will result in a time of about
		* 20us. It should never take longer than this.
		*
		* As such, this wait merely spins, with a udelay.
		*/
		static int ssbi_wait_mask(struct msm_ssbi *ssbi, u32 set_mask, u32 clr_mask)
		{
		u32 timeout = SSBI_TIMEOUT_US;
		@@ -161,6 +170,10 @@ err:
		return ret;
		}

		/*
		* See ssbi_wait_mask for an explanation of the time and the
		* busywait.
		*/
		static inline int
		msm_ssbi_pa_transfer(struct msm_ssbi ssbi, u32 cmd, u8 data)
		{

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