* [PATCH 2/2] ARM: plat-mxc: Fix pwm frequency
[not found] <1309485035-5964-1-git-send-email-troy.kisky@boundarydevices.com>
@ 2011-07-01 8:03 ` Sascha Hauer
2011-07-01 18:53 ` Troy Kisky
0 siblings, 1 reply; 2+ messages in thread
From: Sascha Hauer @ 2011-07-01 8:03 UTC (permalink / raw)
To: linux-arm-kernel
On Thu, Jun 30, 2011 at 06:50:35PM -0700, Troy Kisky wrote:
> The PWMPR register is number of clocks + 2, so include
> a -2 when setting the register. There is currently no rounding
> up, so this may give a higher frequency than requested.
Have you checked this applies to mx2/3 aswell?
Sascha
>
> Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
> ---
> arch/arm/plat-mxc/pwm.c | 8 +++++++-
> 1 files changed, 7 insertions(+), 1 deletions(-)
>
> diff --git a/arch/arm/plat-mxc/pwm.c b/arch/arm/plat-mxc/pwm.c
> index 73f17b2..844415e 100644
> --- a/arch/arm/plat-mxc/pwm.c
> +++ b/arch/arm/plat-mxc/pwm.c
> @@ -76,7 +76,13 @@ int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
> duty_cycles = c;
>
> writel(duty_cycles, pwm->mmio_base + MX3_PWMSAR);
> - writel(period_cycles, pwm->mmio_base + MX3_PWMPR);
> + if (period_cycles < 2)
> + period_cycles = 2;
> + /*
> + * manual says - "A value of zero in the PWMPR will result in
> + * a period of two clock cycles for the output signal.
> + */
> + writel(period_cycles - 2, pwm->mmio_base + MX3_PWMPR);
>
> cr = MX3_PWMCR_PRESCALER(prescale) | MX3_PWMCR_EN;
>
> --
> 1.7.0.4
>
>
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^ permalink raw reply [flat|nested] 2+ messages in thread
* [PATCH 2/2] ARM: plat-mxc: Fix pwm frequency
2011-07-01 8:03 ` [PATCH 2/2] ARM: plat-mxc: Fix pwm frequency Sascha Hauer
@ 2011-07-01 18:53 ` Troy Kisky
0 siblings, 0 replies; 2+ messages in thread
From: Troy Kisky @ 2011-07-01 18:53 UTC (permalink / raw)
To: linux-arm-kernel
On 7/1/2011 1:03 AM, Sascha Hauer wrote:
> On Thu, Jun 30, 2011 at 06:50:35PM -0700, Troy Kisky wrote:
>> The PWMPR register is number of clocks + 2, so include
>> a -2 when setting the register. There is currently no rounding
>> up, so this may give a higher frequency than requested.
>
> Have you checked this applies to mx2/3 aswell?
>
> Sascha
>
>>
>> Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
>> ---
>> arch/arm/plat-mxc/pwm.c | 8 +++++++-
>> 1 files changed, 7 insertions(+), 1 deletions(-)
>>
>> diff --git a/arch/arm/plat-mxc/pwm.c b/arch/arm/plat-mxc/pwm.c
>> index 73f17b2..844415e 100644
>> --- a/arch/arm/plat-mxc/pwm.c
>> +++ b/arch/arm/plat-mxc/pwm.c
>> @@ -76,7 +76,13 @@ int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
>> duty_cycles = c;
>>
>> writel(duty_cycles, pwm->mmio_base + MX3_PWMSAR);
>> - writel(period_cycles, pwm->mmio_base + MX3_PWMPR);
>> + if (period_cycles < 2)
>> + period_cycles = 2;
>> + /*
>> + * manual says - "A value of zero in the PWMPR will result in
>> + * a period of two clock cycles for the output signal.
>> + */
>> + writel(period_cycles - 2, pwm->mmio_base + MX3_PWMPR);
>>
>> cr = MX3_PWMCR_PRESCALER(prescale) | MX3_PWMCR_EN;
>>
>> --
>> 1.7.0.4
>>
>>
>
I just checked. It applies to mx27, mx31, mx25, mx51, mx53.
Thanks for the reminder.
Troy
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[not found] <1309485035-5964-1-git-send-email-troy.kisky@boundarydevices.com>
2011-07-01 8:03 ` [PATCH 2/2] ARM: plat-mxc: Fix pwm frequency Sascha Hauer
2011-07-01 18:53 ` Troy Kisky
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