Message ID | 3F263ABB4EDE344D974E1983B56807734FF6B38D@EX-DAG01.eckelmann.group |
---|---|
State | New |
Headers | show |
Hi Torsten, On Mon, Jul 04, 2011 at 03:24:25PM +0000, Mehnert, Torsten wrote: > i am using barebox and standard linux (2.6.39.1) on my mx25 board. Under > linux i now have the problem > that a sleepwait or busywait results in a factor 1.8 too long waiting time. > So sleep(10) results in ~18 seconds > of waiting. > > I see through the clock registers > and found that the clock source of the general purpose timer is set to > UPLL(240MHz), divided by 2 its 120MHz. > So when 120Mhz is factor 1.8 too much, then the correct value should be > 66MHz. As this value can't be divided from > UPLL i changed the clock source to AHB_DIV(133MHz), get the 66MHz and my > sleep(10) are the proper 10 seconds. > I think that the clock-mx25.c expected the CCM_MCR register to be cleared > completely, which it's not in my case. > > I tested this issue again on the mx25-3stack evaluation board, with the same result. > > Old Kernel message: sched_clock: 32 bits at 120MHz, resolution 8ns, wraps every 35791ms > New Kernel message: sched_clock: 32 bits at 66MHz, resolution 15ns, wraps every 64585ms You should Cc Sascha Hauer <kernel@pengutronix.de> on i.MX related patches. Also, see the tread at http://thread.gmane.org/gmane.linux.ports.arm.kernel/72944, and especially the note of Rob Herring of (then) Freescale. baruch > This patch fixes this issue: > > Request for comment and feedback. > > From: T. Mehnert <t.mehnert@eckelmann.de> > Date: Mon, 4 Jul 2011 15:53:30 +0200 > Subject: [PATCH] GPT clock fix: corrected the clock source > > This patch changes the clock source for the general purpose timer > of the arm/mx25 from UPLL to AHB_DIV. This fixes the problem, > that sleep/busy wating waits factor 1.8 too long. > > Signed-off-by: Torsten Mehnert <t.mehnert@eckelmann.de> > --- > arch/arm/mach-imx/clock-imx25.c | 4 ++++ > 1 files changed, 4 insertions(+), 0 deletions(-) > > diff --git a/arch/arm/mach-imx/clock-imx25.c b/arch/arm/mach-imx/clock-imx25.c > index a65838f..bf1ecda 100644 > --- a/arch/arm/mach-imx/clock-imx25.c > +++ b/arch/arm/mach-imx/clock-imx25.c > @@ -328,6 +328,10 @@ int __init mx25_clocks_init(void) > __raw_writel(__raw_readl(CRM_BASE+0x64) | (1 << 7) | (1 << 0), > CRM_BASE + 0x64); > > + /* Clock source for gpt is ahb_div */ > + __raw_writel(__raw_readl(CRM_BASE+0x64) & ~(1 << 5), > + CRM_BASE + 0x64); > + > mxc_timer_init(&gpt_clk, MX25_IO_ADDRESS(MX25_GPT1_BASE_ADDR), 54); > > return 0; > --
diff --git a/arch/arm/mach-imx/clock-imx25.c b/arch/arm/mach-imx/clock-imx25.c index a65838f..bf1ecda 100644 --- a/arch/arm/mach-imx/clock-imx25.c +++ b/arch/arm/mach-imx/clock-imx25.c @@ -328,6 +328,10 @@ int __init mx25_clocks_init(void) __raw_writel(__raw_readl(CRM_BASE+0x64) | (1 << 7) | (1 << 0), CRM_BASE + 0x64); + /* Clock source for gpt is ahb_div */ + __raw_writel(__raw_readl(CRM_BASE+0x64) & ~(1 << 5), + CRM_BASE + 0x64); + mxc_timer_init(&gpt_clk, MX25_IO_ADDRESS(MX25_GPT1_BASE_ADDR), 54); return 0;