Re: [PATCH 1/3] drm/tegra: vic: Implement explicit reset support

[Jon Hunter <jonathanh@nvidia.com>]

On 23/11/2018 12:06, Thierry Reding wrote:
> From: Thierry Reding <treding@nvidia.com>
> 
> Tegra supports generic PM domains on 64-bit ARM, and if that is enabled,
> the power domain code will make sure that resets are asserted and
> deasserted at appropriate points in time.
> 
> If generic PM domains are not implemented, such as on 32-bit Tegra, the
> resets need to be asserted and deasserted explicitly by the driver.
> 
> Signed-off-by: Thierry Reding <treding@nvidia.com>
> ---
>  drivers/gpu/drm/tegra/vic.c | 35 ++++++++++++++++++++++++++++++++++-
>  1 file changed, 34 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/tegra/vic.c b/drivers/gpu/drm/tegra/vic.c
> index 9fa77405db01..23f530db45ad 100644
> --- a/drivers/gpu/drm/tegra/vic.c
> +++ b/drivers/gpu/drm/tegra/vic.c
> @@ -38,6 +38,7 @@ struct vic {
>  	struct iommu_domain *domain;
>  	struct device *dev;
>  	struct clk *clk;
> +	struct reset_control *rst;
>  
>  	/* Platform configuration */
>  	const struct vic_config *config;
> @@ -56,13 +57,37 @@ static void vic_writel(struct vic *vic, u32 value, unsigned int offset)
>  static int vic_runtime_resume(struct device *dev)
>  {
>  	struct vic *vic = dev_get_drvdata(dev);
> +	int err;
> +
> +	err = clk_prepare_enable(vic->clk);
> +	if (err < 0)
> +		return err;
> +
> +	usleep_range(2000, 4000);

The Tegra genpd code has a usleep_range(10, 20), is that not sufficient
here? If it is, it would be good to be consistent.

> +
> +	err = reset_control_deassert(vic->rst);
> +	if (err < 0)
> +		goto disable;
> +
> +	usleep_range(2000, 4000);
> +
> +	return 0;
>  
> -	return clk_prepare_enable(vic->clk);
> +disable:
> +	clk_disable_unprepare(vic->clk);
> +	return err;
>  }
>  
>  static int vic_runtime_suspend(struct device *dev)
>  {
>  	struct vic *vic = dev_get_drvdata(dev);
> +	int err;
> +
> +	err = reset_control_assert(vic->rst);
> +	if (err < 0)
> +		return err;
> +
> +	usleep_range(2000, 4000);
>  
>  	clk_disable_unprepare(vic->clk);
>  
> @@ -324,6 +349,14 @@ static int vic_probe(struct platform_device *pdev)
>  		return PTR_ERR(vic->clk);
>  	}
>  
> +	if (!dev->pm_domain) {
> +		vic->rst = devm_reset_control_get(dev, "vic");
> +		if (IS_ERR(vic->rst)) {
> +			dev_err(&pdev->dev, "failed to get reset\n");
> +			return PTR_ERR(vic->rst);
> +		}
> +	}
> +
>  	vic->falcon.dev = dev;
>  	vic->falcon.regs = vic->regs;
>  	vic->falcon.ops = &vic_falcon_ops;
> 

Cheers
Jon

-- 
nvpublic
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