Commit 3f7a73b5 authored by David Brown's avatar David Brown Committed by Greg Kroah-Hartman
Browse files

ssbi: Comment the use of udelay() 



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: default avatarDavid Brown <davidb@codeaurora.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 97f00f71

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 @@ msm_ssbi_write_bytes(struct msm_ssbi *ssbi, u16 addr, u8 *buf, int len) 
	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)

{