linux-kernel - Re: [PATCH v6 4/6] clk: qcom: gpucc-sc7280: Add cx collapse reset support

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Date:   Thu, 1 Sep 2022 12:34:49 +0200
From:   Philipp Zabel <p.zabel@...gutronix.de>
To:     Akhil P Oommen <quic_akhilpo@...cinc.com>
Cc:     freedreno <freedreno@...ts.freedesktop.org>,
        dri-devel@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        Rob Clark <robdclark@...il.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Douglas Anderson <dianders@...omium.org>,
        krzysztof.kozlowski@...aro.org, Andy Gross <agross@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 4/6] clk: qcom: gpucc-sc7280: Add cx collapse reset
 support

On Wed, Aug 31, 2022 at 10:48:25AM +0530, Akhil P Oommen wrote:
> Allow a consumer driver to poll for cx gdsc collapse through Reset
> framework.
> 
> Signed-off-by: Akhil P Oommen <quic_akhilpo@...cinc.com>
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> ---
> 
> (no changes since v3)
> 
> Changes in v3:
> - Convert 'struct qcom_reset_ops cx_gdsc_reset' to 'static const' (Krzysztof)
> 
> Changes in v2:
> - Minor update to use the updated custom reset ops implementation
> 
>  drivers/clk/qcom/gpucc-sc7280.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/clk/qcom/gpucc-sc7280.c b/drivers/clk/qcom/gpucc-sc7280.c
> index 9a832f2..fece3f4 100644
> --- a/drivers/clk/qcom/gpucc-sc7280.c
> +++ b/drivers/clk/qcom/gpucc-sc7280.c
> @@ -433,12 +433,22 @@ static const struct regmap_config gpu_cc_sc7280_regmap_config = {
>  	.fast_io = true,
>  };
>  
> +static const struct qcom_reset_ops cx_gdsc_reset = {
> +	.reset = gdsc_wait_for_collapse,

This should be accompanied by a comment explaining the not-quite-reset
nature of this workaround, i.e. what is the prerequisite for this to
actually work as expected?

> +};
> +
> +static const struct qcom_reset_map gpucc_sc7280_resets[] = {
> +	[GPU_CX_COLLAPSE] = { .ops = &cx_gdsc_reset, .priv = &cx_gdsc },
> +};
> +
>  static const struct qcom_cc_desc gpu_cc_sc7280_desc = {
>  	.config = &gpu_cc_sc7280_regmap_config,
>  	.clks = gpu_cc_sc7280_clocks,
>  	.num_clks = ARRAY_SIZE(gpu_cc_sc7280_clocks),
>  	.gdscs = gpu_cc_sc7180_gdscs,
>  	.num_gdscs = ARRAY_SIZE(gpu_cc_sc7180_gdscs),
> +	.resets = gpucc_sc7280_resets,
> +	.num_resets = ARRAY_SIZE(gpucc_sc7280_resets),

See my comment on patch 2. I think instead of adding a const struct
qcom_reset_ops * to gpucc_sc7280_resets, this should just add a const
struct reset_control * to gpu_cc_sc7280_desc.

regards
Philipp