[U-Boot] [PATCH v3 25/57] ram: rk3399: Avoid two channel ZQ Cal Start at the same time

[Kever Yang <kever.yang@rock-chips.com>]

On 2019/7/16 下午7:57, Jagan Teki wrote:
> It is possible in lpddr4 dram, where both the channels would
> start at same time with ZQ Cal Start. If it uses ZQ Call start
> then it will use RZQ.
>
> For example LPDDR4 366 Dual-Die, Quad-Channel Package, RZQ maybe
> connect to both channel. If ZQ Cal Start at the same time,
> it will use the same RZQ.
>
> It is not a problem of using RZQ in both the channels, but can not
> use at the same time.
>
> So, to avoid this, we have an option of dram tINIT3 value for
> increasing the frequency for channel 1.
>
> This patch increase the available tINIT3 with existing running
> dram frequency.
>
> Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
> Signed-off-by: YouMin Chen <cym@rock-chips.com>

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

Thanks,
  - Kever
> ---
>   drivers/ram/rockchip/sdram_rk3399.c | 14 ++++++++++++++
>   1 file changed, 14 insertions(+)
>
> diff --git a/drivers/ram/rockchip/sdram_rk3399.c b/drivers/ram/rockchip/sdram_rk3399.c
> index 023838a301..beb4f6de54 100644
> --- a/drivers/ram/rockchip/sdram_rk3399.c
> +++ b/drivers/ram/rockchip/sdram_rk3399.c
> @@ -550,6 +550,20 @@ static int pctl_cfg(struct dram_info *dram, const struct chan_info *chan,
>   		    sizeof(struct rk3399_ddr_pctl_regs) - 4);
>   	writel(params_ctl[0], &denali_ctl[0]);
>   
> +	/*
> +	 * two channel init at the same time, then ZQ Cal Start
> +	 * at the same time, it will use the same RZQ, but cannot
> +	 * start at the same time.
> +	 *
> +	 * So, increase tINIT3 for channel 1, will avoid two
> +	 * channel ZQ Cal Start at the same time
> +	 */
> +	if (params->base.dramtype == LPDDR4 && channel == 1) {
> +		tmp = ((params->base.ddr_freq * MHz + 999) / 1000);
> +		tmp1 = readl(&denali_ctl[14]);
> +		writel(tmp + tmp1, &denali_ctl[14]);
> +	}
> +
>   	copy_to_reg(denali_pi, &params->pi_regs.denali_pi[0],
>   		    sizeof(struct rk3399_ddr_pi_regs));
>