linux-kernel - Re: [PATCH v5 3/3] soc: mediatek: mtk-svs: add thermal voltage compensation if needed

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Date:   Thu, 2 Feb 2023 13:58:56 +0100
From:   Matthias Brugger <matthias.bgg@...il.com>
To:     Roger Lu <roger.lu@...iatek.com>,
        Enric Balletbo Serra <eballetbo@...il.com>,
        Kevin Hilman <khilman@...nel.org>,
        Nicolas Boichat <drinkcat@...gle.com>
Cc:     Fan Chen <fan.chen@...iatek.com>,
        Jia-wei Chang <jia-wei.chang@...iatek.com>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org,
        Project_Global_Chrome_Upstream_Group@...iatek.com
Subject: Re: [PATCH v5 3/3] soc: mediatek: mtk-svs: add thermal voltage
 compensation if needed

Hi Roger,

I have some doubts, please see below.

On 02/02/2023 13:41, Roger Lu wrote:
> Some extreme test environment may keep IC temperature very low or very high
> during system boot stage. For stability concern, we add thermal voltage
> compenstation if needed no matter svs bank phase is in init02 or mon mode.
> 
> Signed-off-by: Roger Lu <roger.lu@...iatek.com>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
> ---
>   drivers/soc/mediatek/mtk-svs.c | 17 +++++++++--------
>   1 file changed, 9 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/soc/mediatek/mtk-svs.c b/drivers/soc/mediatek/mtk-svs.c
> index 299f580847bd..e104866d1ab5 100644
> --- a/drivers/soc/mediatek/mtk-svs.c
> +++ b/drivers/soc/mediatek/mtk-svs.c
> @@ -558,7 +558,7 @@ static int svs_adjust_pm_opp_volts(struct svs_bank *svsb)
>   	}
>   
>   	/* Get thermal effect */
> -	if (svsb->phase == SVSB_PHASE_MON) {
> +	if (!IS_ERR_OR_NULL(svsb->tzd)) {
>   		ret = thermal_zone_get_temp(svsb->tzd, &tzone_temp);
>   		if (ret || (svsb->temp > SVSB_TEMP_UPPER_BOUND &&
>   			    svsb->temp < SVSB_TEMP_LOWER_BOUND)) {
> @@ -573,7 +573,8 @@ static int svs_adjust_pm_opp_volts(struct svs_bank *svsb)
>   			temp_voffset += svsb->tzone_ltemp_voffset;
>   
>   		/* 2-line bank update all opp volts when running mon mode */
> -		if (svsb->type == SVSB_HIGH || svsb->type == SVSB_LOW) {
> +		if (svsb->phase == SVSB_PHASE_MON && (svsb->type == SVSB_HIGH ||
> +						      svsb->type == SVSB_LOW)) {
>   			opp_start = 0;
>   			opp_stop = svsb->opp_count;
>   		}
> @@ -589,11 +590,6 @@ static int svs_adjust_pm_opp_volts(struct svs_bank *svsb)
>   			/* do nothing */
>   			goto unlock_mutex;
>   		case SVSB_PHASE_INIT02:
> -			svsb_volt = max(svsb->volt[i], svsb->vmin);
> -			opp_volt = svs_bank_volt_to_opp_volt(svsb_volt,
> -							     svsb->volt_step,
> -							     svsb->volt_base);
> -			break;
>   		case SVSB_PHASE_MON:
>   			svsb_volt = max(svsb->volt[i] + temp_voffset, svsb->vmin);
>   			opp_volt = svs_bank_volt_to_opp_volt(svsb_volt,
> @@ -1683,7 +1679,7 @@ static int svs_bank_resource_setup(struct svs_platform *svsp)
>   			}
>   		}
>   
> -		if (svsb->mode_support & SVSB_MODE_MON) {
> +		if (!IS_ERR_OR_NULL(svsb->tzone_name)) {
>   			svsb->tzd = thermal_zone_get_zone_by_name(svsb->tzone_name);
>   			if (IS_ERR(svsb->tzd)) {
>   				dev_err(svsb->dev, "cannot get \"%s\" thermal zone\n",
> @@ -2127,6 +2123,7 @@ static struct svs_bank svs_mt8192_banks[] = {
>   		.type			= SVSB_LOW,
>   		.set_freq_pct		= svs_set_bank_freq_pct_v3,
>   		.get_volts		= svs_get_bank_volts_v3,
> +		.tzone_name		= "gpu1",
>   		.volt_flags		= SVSB_REMOVE_DVTFIXED_VOLT,
>   		.mode_support		= SVSB_MODE_INIT02,
>   		.opp_count		= MAX_OPP_ENTRIES,
> @@ -2144,6 +2141,10 @@ static struct svs_bank svs_mt8192_banks[] = {
>   		.core_sel		= 0x0fff0100,
>   		.int_st			= BIT(0),
>   		.ctl0			= 0x00540003,
> +		.tzone_htemp		= 85000,
> +		.tzone_htemp_voffset	= 0,
> +		.tzone_ltemp		= 25000,
> +		.tzone_ltemp_voffset	= 7,

Which is the exact same tzone then in the other bank. Which brings me to a good 
point:
Is the tzone bank specific or the same for all banks?
At least for mt8192 they are not. I suppose with this change to the code mt8183 
could take advantage of this on all it's banks as well. In that case, can we 
start to restructure the struct svs_bank to only have the tzone values declared 
once?

Background is that I'm very unhappy with the svs_bank data strucutre. It seems 
like a "throw it all in here". It should be structured for functional parts of 
the banks. Maybe using structs, maybe unions where possible. In any case having 
a flat struct of over 50 members isn't really what we want.

Regards,
Matthias

>   	},
>   	{
>   		.sw_id			= SVSB_GPU,