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SubjectRe: [PATCH 5/6] media: sun4i: Add H3 deinterlace driver
Hi,

On Thu, Sep 12, 2019 at 07:51:31PM +0200, Jernej Skrabec wrote:
> + dev->regmap = devm_regmap_init_mmio(dev->dev, dev->base,
> + &deinterlace_regmap_config);
> + if (IS_ERR(dev->regmap)) {
> + dev_err(dev->dev, "Couldn't create deinterlace regmap\n");
> +
> + return PTR_ERR(dev->regmap);
> + }
> +
> + ret = clk_prepare_enable(dev->bus_clk);
> + if (ret) {
> + dev_err(dev->dev, "Failed to enable bus clock\n");
> +
> + return ret;
> + }

Do you need to keep the bus clock enabled all the time? Usually, for
the SoCs that have a reset line, you only need it to read / write to
the registers, not to have the controller actually running.

If you don't, then regmap_init_mmio_clk will take care of that for
you.

> + clk_set_rate(dev->mod_clk, 300000000);
> +
> + ret = clk_prepare_enable(dev->mod_clk);
> + if (ret) {
> + dev_err(dev->dev, "Failed to enable mod clock\n");
> +
> + goto err_bus_clk;
> + }
> +
> + ret = clk_prepare_enable(dev->ram_clk);
> + if (ret) {
> + dev_err(dev->dev, "Failed to enable ram clock\n");
> +
> + goto err_mod_clk;
> + }
> +
> + ret = reset_control_reset(dev->rstc);
> + if (ret) {
> + dev_err(dev->dev, "Failed to apply reset\n");
> +
> + goto err_ram_clk;
> + }

This could be moved to a runtime_pm hook, with get_sync called in the
open. That way you won't leave the device powered on if it's unused.

> +struct deinterlace_dev {
> + struct v4l2_device v4l2_dev;
> + struct video_device vfd;
> + struct device *dev;
> + struct v4l2_m2m_dev *m2m_dev;
> +
> + /* Device file mutex */
> + struct mutex dev_mutex;
> +
> + void __iomem *base;
> + struct regmap *regmap;

Do you need to store the base address in that structure if you're
using the regmap?

Maxime

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