[PATCH] ARM: mx28: clock-mx28: Use a proper timeout mechanism
From: Wolfram Sang <hidden>
Date: 2012-01-23 21:18:54
Hi Fabio, On Mon, Jan 23, 2012 at 12:41:07PM -0200, Fabio Estevam wrote:
Introduce a function for checking the busy bits of CLKCTRL register that uses a proper timeout mechanism. Remove parts of code that use busy loops and replace them with the mxs_clkctrl_timeout() function. Tested on a mx28evk by performing audio playback. Suggested-by: Wolfram Sang <redacted> Signed-off-by: Fabio Estevam <redacted>
Is there a difference in the two versions you sent?
quoted hunk ↗ jump to hunk
--- arch/arm/mach-mxs/clock-mx28.c | 64 +++++++++++++--------------------------- 1 files changed, 21 insertions(+), 43 deletions(-)diff --git a/arch/arm/mach-mxs/clock-mx28.c b/arch/arm/mach-mxs/clock-mx28.c index 5d68e41..ad5482d 100644 --- a/arch/arm/mach-mxs/clock-mx28.c +++ b/arch/arm/mach-mxs/clock-mx28.c@@ -38,6 +38,7 @@ #define DIGCTRL_BASE_ADDR MX28_IO_ADDRESS(MX28_DIGCTL_BASE_ADDR) #define PARENT_RATE_SHIFT 8 +#define CLKCTRL_TIMEOUT 10 /* 10 ms = 1 jiffy */
I'd remove the jiffy-part of the comment to prevent belief that the relationship will always be true.
quoted hunk ↗ jump to hunk
static struct clk pll2_clk; static struct clk cpu_clk;@@ -127,6 +128,20 @@ static unsigned long pll2_clk_get_rate(struct clk *clk) return 50000000; } +static int mxs_clkctrl_timeout(unsigned int reg_offset, unsigned int mask) +{ + unsigned long timeout = jiffies + msecs_to_jiffies(CLKCTRL_TIMEOUT); + while (readl_relaxed(CLKCTRL_BASE_ADDR + reg_offset) & mask) {
Hmm, this is a lot better, yet not perfect. You could be scheduled away here for 10ms and then you had only checked at t=0. However, I think it makes more sense to introduce a generic timeout-loop somehow and then convert to it later. This is my homework, though...
+ if (time_after(jiffies, timeout)) {
+ pr_err("%s: divider writing timeout\n", __func__);__func__ is probably not useful here. Perhaps reg and mask?
+ return -ETIMEDOUT; + } +
Remove empty line.
+ } + + return 0; +} +
Rest looked good from a glimpse. Regards, Wolfram -- Pengutronix e.K. | Wolfram Sang | Industrial Linux Solutions | http://www.pengutronix.de/ | -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 198 bytes Desc: Digital signature URL: <http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20120123/6bdaf43a/attachment.sig>