Premi, Sanjeev wrote:
>> -----Original Message-----
>> From: Premi, Sanjeev
>> Sent: Friday, January 29, 2010 6:44 PM
>> To: u-boot@lists.denx.de
>> Cc: Premi, Sanjeev; Hiremath, Vaibhav
>> Subject: [PATCHv2] OMAP3: Avoid re-write to PRM_CLKSRC_CTRL
>>
>> The function get_osc_clk_speed() is used to determine the master
>> clock. If SYS_CLK is being divided by 2, the divider is changed
>> to 1 - without following any sequence.
>>
>> Before reaching this function, some of the clocks have already
>> been set (by x-loader or equiv) OR power-on defaults are in use.
>> This change is too sudden, leading to instability beyond certain
>> tolerance zone.
>>
>> The problem was observed with DM3730 (silimar to OMAP3630), on
>> the OMAP3EVM.
>>
>> This patch removes the step to change clock divider. Instead,
>> uses a multiplication factor (if needed). Mathematically, the
>> formula is unchanged.
>>
>> Tested on OMAP3EVM with OMAP3530 and DM3730.
>>
>> Signed-off-by: Sanjeev Premi <pr...@ti.com>
>> Signed-off-by: Hiremath Vaibhav <hvaib...@ti.com>
>> ---
>> cpu/arm_cortexa8/omap3/clock.c | 15 +++++++++++----
>> 1 files changed, 11 insertions(+), 4 deletions(-)
>>
>> diff --git a/cpu/arm_cortexa8/omap3/clock.c
>> b/cpu/arm_cortexa8/omap3/clock.c
>> index 174c453..e8189b4 100644
>> --- a/cpu/arm_cortexa8/omap3/clock.c
>> +++ b/cpu/arm_cortexa8/omap3/clock.c
>> @@ -40,7 +40,7 @@
>>
>> **************************************************************
>> ***************/
>> u32 get_osc_clk_speed(void)
>> {
>> - u32 start, cstart, cend, cdiff, val;
>> + u32 start, cstart, cend, cdiff, cdiv, val;
>> struct prcm *prcm_base = (struct prcm *)PRCM_BASE;
>> struct prm *prm_base = (struct prm *)PRM_BASE;
>> struct gptimer *gpt1_base = (struct gptimer *)OMAP34XX_GPT1;
>> @@ -48,9 +48,13 @@ u32 get_osc_clk_speed(void)
>>
>> val = readl(&prm_base->clksrc_ctrl);
>>
>> - /* If SYS_CLK is being divided by 2, remove for now */
>> - val = (val & (~SYSCLKDIV_2)) | SYSCLKDIV_1;
>> - writel(val, &prm_base->clksrc_ctrl);
>> + if (val & SYSCLKDIV_2)
>> + cdiv = 2;
>> + else if (val & SYSCLKDIV_1)
>> + cdiv = 1;
>> + else
>> + /*Should never reach here! (Assume divider as 1) */
>> + cdiv = 1;
>>
>> /* enable timer2 */
>> val = readl(&prcm_base->clksel_wkup) | CLKSEL_GPT1;
>> @@ -83,6 +87,9 @@ u32 get_osc_clk_speed(void)
>> cend = readl(&gpt1_base->tcrr); /* get end
>> sys_clk count */
>> cdiff = cend - cstart; /* get elapsed ticks */
>>
>> + if (cdiv == 2)
>> + cdiff *= 2;
>> +
>> /* based on number of ticks assign speed */
>> if (cdiff > 19000)
>> return S38_4M;
>> --
>> 1.6.2.2
>>
>>
>
> Tom, Sandeep,
>
> Just wanted to check the status of this patch.
>
Ack-ed
This looks fine.
Thanks
Tom
> Best regards,
> Sanjeev
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