[U-Boot] [PATCH] rockchip: clk: rk3188: update dpll settings to make EMAC work

[Kever Yang]

Hi Philipp,

    Sorry for reply so late.
On 02/26/2018 07:28 PM, Dr. Philipp Tomsich wrote:
> Kever,
>
> please review.
>
> Thanks,
> Philipp.
>
>> On 26 Feb 2018, at 12:27, Alexander Kochetkov <al.kochet at gmail.com> wrote:
>>
>> The patch set dpll settings for 300MHz to values used by binary
>> blob[1]. With new values dpll still generate 300MHz clock, but
>> EMAC work. Probably with new values dpll generate more stable clock.
>>
>> dpll on rk3188 provide clocks to DDR and EMAC. With current
>> dpll settings EMAC doesn't work on radxa rock. EMAC sends packets
>> to network, but it doesn't receive anything. ifconfig shows a lot
>> of framing errors.
>>
>> [1] https://github.com/linux-rockchip/u-boot-rockchip/blob/u-boot-rk3288/
>>    tools/rk_tools/3188_LPDDR2_300MHz_DDR3_300MHz_20130830.bin
>>
>> Signed-off-by: Alexander Kochetkov <al.kochet at gmail.com>
>> ---
>> drivers/clk/rockchip/clk_rk3188.c |    2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/clk/rockchip/clk_rk3188.c b/drivers/clk/rockchip/clk_rk3188.c
>> index 6451c95..f674e60 100644
>> --- a/drivers/clk/rockchip/clk_rk3188.c
>> +++ b/drivers/clk/rockchip/clk_rk3188.c
>> @@ -123,7 +123,7 @@ static int rkclk_configure_ddr(struct rk3188_cru *cru, struct rk3188_grf *grf,
>> 			       unsigned int hz, bool has_bwadj)
>> {
>> 	static const struct pll_div dpll_cfg[] = {
>> -		{.nf = 25, .nr = 2, .no = 1},
>> +		{.nf = 75, .nr = 1, .no = 6},

Rockchip always prefer to use nr=1 even if we can only get a frequency
close to target frequency,
because this setting can get smaller jitter. Some of IP like jitter may
very sensitive to this setting.

Reviewed-by: Kever Yang <kever.yang at rock-chips.com>

Thanks,
- Kever
>> 		{.nf = 400, .nr = 9, .no = 2},
>> 		{.nf = 500, .nr = 9, .no = 2},
>> 		{.nf = 100, .nr = 3, .no = 1},
>> -- 
>> 1.7.9.5
>>
>