Re: [PATCH 1/4] CLK: ti: dra7: Initialize USB_DPLL

Nishanth Menon
2013-08-02T12:52:48Z

On 08/02/2013 05:57 AM, Tero Kristo wrote:
> On 08/02/2013 10:30 AM, Roger Quadros wrote:
>> Hi Nishant,
>>
>> On 08/01/2013 06:06 PM, Nishanth Menon wrote:
>>> On 08/01/2013 09:58 AM, Roger Quadros wrote:
>>>> USB_DPLL must be initialized and locked at boot so that
>>>> USB modules can work.
>>>>
>>>> Also program USB_DLL_M2 output to half rate.
>>>>
>>>> Signed-off-by: Roger Quadros <rogerq@ti.com>
>>>> ---
>>>> drivers/clk/omap/clk-7xx.c | 11 +++++++++++
>>>> 1 files changed, 11 insertions(+), 0 deletions(-)
>>>>
>>>> diff --git a/drivers/clk/omap/clk-7xx.c b/drivers/clk/omap/clk-7xx.c
>>>> index ddb39dd..f444513 100644
>>>> --- a/drivers/clk/omap/clk-7xx.c
>>>> +++ b/drivers/clk/omap/clk-7xx.c
>>>> @@ -19,6 +19,7 @@
>>>>
>>>> #define DRA7_DPLL_ABE_DEFFREQ 361267200
>>>> #define DRA7_DPLL_GMAC_DEFFREQ 1000000000
>>>> +#define DRA7_DPLL_USB_DEFFREQ 960000000
>>>>
>>>>
>>>> static struct omap_dt_clk dra7xx_clks[] = {
>>>> @@ -63,5 +64,15 @@ int __init dra7xx_clk_init(void)
>>>> if (rc)
>>>> pr_err("%s: failed to configure GMAC DPLL!\n", __func__);
>>>>
>>>> + dpll_ck = clk_get_sys(NULL, "dpll_usb_ck");
>>>> + rc = clk_set_rate(dpll_ck, DRA7_DPLL_USB_DEFFREQ);
>>>> + if (rc)
>>>> + pr_err("%s: failed to configure USB DPLL!\n", __func__);
>>>> +
>>>> + dpll_ck = clk_get_sys(NULL, "dpll_usb_m2_ck");
>>>> + rc = clk_set_rate(dpll_ck, DRA7_DPLL_USB_DEFFREQ/2);
>>>> + if (rc)
>>>> + pr_err("%s: failed to set USB_DPLL M2 OUT\n", __func__);
>>>> +
>>>> return rc;
>>>> }
>>>>
>>> As I had mentioned on [1] - we are going to see similar needs keep
>>> popping up. there is no need to hack this up for even more
>>> peripherals :(
>>>
>>> http://marc.info/?l=linux-omap&m=137536803106017&w=2
>>>
>> The DPLLs need to be initialized irrespective of whether peripheral
>> drivers are present or not.
>> We have seen cases where the SoC fails to enter RETention if the DPLLS
>> are not correctly
>> configured.
>>
>> But I agree with you that we should be able to initialize it by
>> specifying the initial rate via Clock Data.
>>
>> This patch can be removed when the appropriate feature is added in
>> OMAP clock core.
>
> ... not OMAP clock core, I would say clock core. This is again a feature
> we can work with once we have initial support in place.

OK. /me gives up for now. but please squash this into your set.

--
Regards,
Nishanth Menon