rk3399_dmc - anybody has it working?

[Kever Yang]

Hi Jack,

     Rockchip kernel + ATF is the one make sure of rk3399_dmc devfreq 
driver is working,

so I would suggest you to compare relate difference with mainline, eg. 
the dts of dmc

node for lpddr4.

     Which frequency do you want to change to during your test?


Thanks,

- Kever

On 2020/6/19 下午6:16, Jack Mitchell wrote:
> Hi all,
>
> Has anybody had any success in enabling the rk3399_dmc devfreq driver.
> I've been hacking on it for a few days now with very limited success.
>
> Our board has single channel lpddr4 which can run stable at either
> 400/800 MHz when set from the u-boot rk3399 sdram driver.
>
> I've tried numerous combinations such as:
>
> 1) mainline u-boot v2020.07-rc4 TPL (RAM init)/SPL+proper + mainline ATF
> + linux mainline 5.5.8
>
> This locks up when attempting to set the ddr clock rate at this point:
>
> 		/* PHY_LOW_FREQ_SEL */
> 		/* DENALI_PHY_913 1bit offset_0 */
> 		if (timing_config->freq > 400)
> 			mmio_clrbits_32(PHY_REG(i, 913), 1);
> 		else
> 			mmio_setbits_32(PHY_REG(i, 913), 1);
>
> https://github.com/ARM-software/arm-trusted-firmware/blob/master/plat/rockchip/rk3399/drivers/dram/dfs.c#L1521
>
> 2) rockchip DDR init + mainline uboot SPL+proper + mainline ATF + linux
> mainline 5.5.8
>
> This locks up at the same point as above.
>
> 3) rockchip DDR init + mainline uboot SPL+proper + rockchip binary ATF +
> linux mainline 5.5.8
>
> This manages to set the rate but then instantly crashes the system,
> probably something to do with ram config options in the reconfiguration
> stage, but I have no view to this as the ATF is proprietary.
>
> If anybody has any documentation on this, or could point me in the
> direction of someone who does have documentation that would help a lot.
> Any war stories for others who have this working would also be
> appreciated, there have been some changes to this code fairly recently,
> so even though there are no current users in kernel, I assume someone
> somewhere has this working?
>
> Regards,
> Jack.
>
>
>
>