Re: [RFC PATCH 03/10] devfreq: rk3399_dmc: Pass ODT and auto power down parameters to TF-A.

From: Chanwoo Choi
Date: Mon May 14 2018 - 18:20:23 EST

Hi,

On 2018ë 05ì 15ì 06:16, Enric Balletbo i Serra wrote:
> Trusted Firmware-A (TF-A) for rk3399 implements a SiP call to get the
> on-die termination (ODT) and auto power down parameters from kernel,
> this patch adds the functionality to do this. Also, if DDR clock
> frequency is lower than the on-die termination (ODT) disable frequency
> this driver should disable the DDR ODT.

I have a question.
'disable frequency' is the same meaning of 'disable the DDR ODT'?

>
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx>
> ---
>
> drivers/devfreq/rk3399_dmc.c | 50 ++++++++++++++++++++++++++++-
> include/soc/rockchip/rockchip_sip.h | 1 +
> 2 files changed, 50 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/devfreq/rk3399_dmc.c b/drivers/devfreq/rk3399_dmc.c
> index d5c03e5abe13..cc1bbca3fb15 100644
> --- a/drivers/devfreq/rk3399_dmc.c
> +++ b/drivers/devfreq/rk3399_dmc.c
> @@ -18,14 +18,17 @@
> #include <linux/devfreq.h>
> #include <linux/devfreq-event.h>
> #include <linux/interrupt.h>
> +#include <linux/mfd/syscon.h>
> #include <linux/module.h>
> #include <linux/of.h>
> #include <linux/platform_device.h>
> #include <linux/pm_opp.h>
> +#include <linux/regmap.h>
> #include <linux/regulator/consumer.h>
> #include <linux/rwsem.h>
> #include <linux/suspend.h>
>
> +#include <soc/rockchip/rk3399_grf.h>
> #include <soc/rockchip/rockchip_sip.h>
>
> struct dram_timing {
> @@ -69,8 +72,11 @@ struct rk3399_dmcfreq {
> struct mutex lock;
> struct dram_timing timing;
> struct regulator *vdd_center;
> + struct regmap *regmap_pmu;
> unsigned long rate, target_rate;
> unsigned long volt, target_volt;
> + unsigned int odt_dis_freq;
> + int odt_pd_arg0, odt_pd_arg1;
> };
>
> static int rk3399_dmcfreq_target(struct device *dev, unsigned long *freq,
> @@ -80,6 +86,8 @@ static int rk3399_dmcfreq_target(struct device *dev, unsigned long *freq,
> struct dev_pm_opp *opp;
> unsigned long old_clk_rate = dmcfreq->rate;
> unsigned long target_volt, target_rate;
> + struct arm_smccc_res res;
> + int dram_flag;
> int err;
>
> opp = devfreq_recommended_opp(dev, freq, flags);
> @@ -95,6 +103,15 @@ static int rk3399_dmcfreq_target(struct device *dev, unsigned long *freq,
>
> mutex_lock(&dmcfreq->lock);
>
> + dram_flag = 0;

Also, if dram_flag is 0, it mean that disable ODT frequency?
If it's right, you better to define the precise variables as following
instead of just integer(0 or 1).
For example,
- ROCKCHIP_SIP_DRAM_FREQ_ENABLE
- ROCKCHIP_SIP_DRAM_FREQ_DISABLE

> + if (target_rate >= dmcfreq->odt_dis_freq)
> + dram_flag = 1;
> +
> + arm_smccc_smc(ROCKCHIP_SIP_DRAM_FREQ, dmcfreq->odt_pd_arg0,
> + dmcfreq->odt_pd_arg1,
> + ROCKCHIP_SIP_CONFIG_DRAM_SET_ODT_PD,
> + dram_flag, 0, 0, 0, &res);
> +

This operation is special for only rk3399_dmc. It is difficult
to understand what to do. I recommend you better to add the detailed comment
with code.

> /*
> * If frequency scaling from low to high, adjust voltage first.
> * If frequency scaling from high to low, adjust frequency first.
> @@ -294,11 +311,13 @@ static int rk3399_dmcfreq_probe(struct platform_device *pdev)
> {
> struct arm_smccc_res res;
> struct device *dev = &pdev->dev;
> - struct device_node *np = pdev->dev.of_node;
> + struct device_node *np = pdev->dev.of_node, *node;
> struct rk3399_dmcfreq *data;
> int ret, index, size;
> uint32_t *timing;
> struct dev_pm_opp *opp;
> + u32 ddr_type;
> + u32 val;
>
> data = devm_kzalloc(dev, sizeof(struct rk3399_dmcfreq), GFP_KERNEL);
> if (!data)
> @@ -334,6 +353,29 @@ static int rk3399_dmcfreq_probe(struct platform_device *pdev)
> return ret;
> }
>
> + /* Try to find the optional reference to the pmu syscon */
> + node = of_parse_phandle(np, "rockchip,pmu", 0);
> + if (node) {
> + data->regmap_pmu = syscon_node_to_regmap(node);
> + if (IS_ERR(data->regmap_pmu))
> + return PTR_ERR(data->regmap_pmu);
> + }
> +
> + /* Get DDR type */
> + regmap_read(data->regmap_pmu, RK3399_PMUGRF_OS_REG2, &val);
> + ddr_type = (val >> RK3399_PMUGRF_DDRTYPE_SHIFT) &
> + RK3399_PMUGRF_DDRTYPE_MASK;
> +
> + /* Get the odt_dis_freq parameter in function of the DDR type */
> + if (ddr_type == RK3399_PMUGRF_DDRTYPE_DDR3)
> + data->odt_dis_freq = data->timing.ddr3_odt_dis_freq;
> + else if (ddr_type == RK3399_PMUGRF_DDRTYPE_LPDDR3)
> + data->odt_dis_freq = data->timing.lpddr3_odt_dis_freq;
> + else if (ddr_type == RK3399_PMUGRF_DDRTYPE_LPDDR4)
> + data->odt_dis_freq = data->timing.lpddr4_odt_dis_freq;
> + else
> + return -EINVAL;
> +

how about using 'switch' statement?

> /*
> * Get dram timing and pass it to arm trust firmware,
> * the dram drvier in arm trust firmware will get these
> @@ -358,6 +400,12 @@ static int rk3399_dmcfreq_probe(struct platform_device *pdev)
> ROCKCHIP_SIP_CONFIG_DRAM_INIT,
> 0, 0, 0, 0, &res);
>
> + data->odt_pd_arg0 = (data->timing.sr_idle & 0xff) |
> + ((data->timing.sr_mc_gate_idle & 0xff) << 8) |
> + ((data->timing.standby_idle & 0xffff) << 16);
> + data->odt_pd_arg1 = (data->timing.pd_idle & 0xfff) |
> + ((data->timing.srpd_lite_idle & 0xfff) << 16);
> +

odt_pd_arg0 and odt_pd_arg1 might be used for disabling/enabling the ODT frequency.
As I commented, it depend on only rk3399_dmc. You better to add detailed comment.

And I prefer to define the XXX_SHIFT/XXX_MASK definition instead of
using 8/16/0xff/0xffff for the readability.

> /*
> * We add a devfreq driver to our parent since it has a device tree node
> * with operating points.
> diff --git a/include/soc/rockchip/rockchip_sip.h b/include/soc/rockchip/rockchip_sip.h
> index 7e28092c4d3d..ad9482c56797 100644
> --- a/include/soc/rockchip/rockchip_sip.h
> +++ b/include/soc/rockchip/rockchip_sip.h
> @@ -23,5 +23,6 @@
> #define ROCKCHIP_SIP_CONFIG_DRAM_GET_RATE 0x05
> #define ROCKCHIP_SIP_CONFIG_DRAM_CLR_IRQ 0x06
> #define ROCKCHIP_SIP_CONFIG_DRAM_SET_PARAM 0x07
> +#define ROCKCHIP_SIP_CONFIG_DRAM_SET_ODT_PD 0x08
>
> #endif
>


--
Best Regards,
Chanwoo Choi
Samsung Electronics