linux-kernel - Re: [PATCH v2 6/6] venus: pm_helpers: Use dev_pm_genpd_set

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Message-ID: <ef031105-3b77-484d-8f47-a6c0233dd9c2@linaro.org>
Date:   Wed, 16 Aug 2023 19:58:51 +0200
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Abel Vesa <abel.vesa@...aro.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Kevin Hilman <khilman@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Andy Gross <agross@...nel.org>,
        Mike Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Taniya Das <tdas@....qualcomm.com>
Cc:     linux-pm@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-msm@...r.kernel.org,
        Jagadeesh Kona <quic_jkona@...cinc.com>
Subject: Re: [PATCH v2 6/6] venus: pm_helpers: Use dev_pm_genpd_set_hwmode to
 switch GDSC mode

On 16.08.2023 16:57, Abel Vesa wrote:
> From: Jagadeesh Kona <quic_jkona@...cinc.com>
> 
> This change demonstrates the use of dev_pm_genpd_set_hwmode API from
> video driver to switch the video mvs0 gdsc to SW/HW modes at runtime
> based on requirement.
> 
> This change adds a new boolean array member vcodec_pmdomains_hwctrl in
> venus_resources structure to indicate if GDSC's have HW control support
> or not. This data is used in vcodec_control_v4() to check if GDSC has
> support to switch to HW control mode and then call dev_pm_genpd_set_hwmode
> to switch the GDSC mode.
> 
> Signed-off-by: Jagadeesh Kona <quic_jkona@...cinc.com>
> Signed-off-by: Abel Vesa <abel.vesa@...aro.org>
> ---
[...]

>  static int vcodec_control_v4(struct venus_core *core, u32 coreid, bool enable)
>  {
> -	void __iomem *ctrl, *stat;
> -	u32 val;
> -	int ret;
> -
> -	if (IS_V6(core)) {
> -		ctrl = core->wrapper_base + WRAPPER_CORE_POWER_CONTROL_V6;
> -		stat = core->wrapper_base + WRAPPER_CORE_POWER_STATUS_V6;
> -	} else if (coreid == VIDC_CORE_ID_1) {
> -		ctrl = core->wrapper_base + WRAPPER_VCODEC0_MMCC_POWER_CONTROL;
> -		stat = core->wrapper_base + WRAPPER_VCODEC0_MMCC_POWER_STATUS;
> -	} else {
> -		ctrl = core->wrapper_base + WRAPPER_VCODEC1_MMCC_POWER_CONTROL;
> -		stat = core->wrapper_base + WRAPPER_VCODEC1_MMCC_POWER_STATUS;
> -	}
> -
> -	if (enable) {
> -		writel(0, ctrl);
> -
> -		ret = readl_poll_timeout(stat, val, val & BIT(1), 1, 100);
> -		if (ret)
> -			return ret;
> -	} else {
> -		writel(1, ctrl);
This removal cries for better explanation.

Has the venus hw been setting some registers that alter the GDSC's state?
Or the hardware's expectations of the GDSC state?

Konrad