linux-kernel - Re: [PATCH 5/9] media: platform: Add Sunxi Cedrus decoder driver

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Date:   Fri, 9 Mar 2018 14:57:02 +0100
From:   Maxime Ripard <maxime.ripard@...tlin.com>
To:     Paul Kocialkowski <paul.kocialkowski@...tlin.com>
Cc:     linux-media@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-sunxi@...glegroups.com, Icenowy Zheng <icenowy@...c.xyz>,
        Florent Revest <revestflo@...il.com>,
        Alexandre Courbot <acourbot@...omium.org>,
        Hans Verkuil <hans.verkuil@...co.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Thomas van Kleef <thomas@...sch.nl>,
        "Signed-off-by : Bob Ham" <rah@...trans.net>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Chen-Yu Tsai <wens@...e.org>
Subject: Re: [PATCH 5/9] media: platform: Add Sunxi Cedrus decoder driver

Hi,

On Fri, Mar 09, 2018 at 11:14:41AM +0100, Paul Kocialkowski wrote:
> +/*
> + * mem2mem callbacks
> + */
> +
> +void job_abort(void *priv)
> +{}

Is that still needed?

> +/*
> + * device_run() - prepares and starts processing
> + */
> +void device_run(void *priv)
> +{

This function (and the one above) should probably made static. Or at
least if you can't, they should have a much more specific name in
order not to conflict with anything from the core.


> +	/*
> +	 * The VPU is only able to handle bus addresses so we have to subtract
> +	 * the RAM offset to the physcal addresses
> +	 */
> +	in_buf     -= PHYS_OFFSET;
> +	out_luma   -= PHYS_OFFSET;
> +	out_chroma -= PHYS_OFFSET;

You should take care of that by putting it in the dma_pfn_offset field
of the struct device (at least before we come up with something
better).

You'll then be able to use the dma_addr_t directly without modifying it.

> +	vpu->syscon = syscon_regmap_lookup_by_phandle(vpu->dev->of_node,
> +						      "syscon");
> +	if (IS_ERR(vpu->syscon)) {
> +		vpu->syscon = NULL;
> +	} else {
> +		regmap_write_bits(vpu->syscon, SYSCON_SRAM_CTRL_REG0,
> +				  SYSCON_SRAM_C1_MAP_VE,
> +				  SYSCON_SRAM_C1_MAP_VE);
> +	}

This should be using our SRAM controller driver (and API), see
Documentation/devicetree/bindings/sram/sunxi-sram.txt
include/linux/soc/sunxi/sunxi_sram.h

> +	ret = clk_prepare_enable(vpu->ahb_clk);
> +	if (ret) {
> +		dev_err(vpu->dev, "could not enable ahb clock\n");
> +		return -EFAULT;
> +	}
> +	ret = clk_prepare_enable(vpu->mod_clk);
> +	if (ret) {
> +		clk_disable_unprepare(vpu->ahb_clk);
> +		dev_err(vpu->dev, "could not enable mod clock\n");
> +		return -EFAULT;
> +	}
> +	ret = clk_prepare_enable(vpu->ram_clk);
> +	if (ret) {
> +		clk_disable_unprepare(vpu->mod_clk);
> +		clk_disable_unprepare(vpu->ahb_clk);
> +		dev_err(vpu->dev, "could not enable ram clock\n");
> +		return -EFAULT;
> +	}

Ideally, this should be using runtime_pm to manage the device power
state, and disable it when not used.

> +	reset_control_assert(vpu->rstc);
> +	reset_control_deassert(vpu->rstc);

You can use reset_control_reset here

> +	return 0;
> +}
> +
> +void sunxi_cedrus_hw_remove(struct sunxi_cedrus_dev *vpu)
> +{
> +	clk_disable_unprepare(vpu->ram_clk);
> +	clk_disable_unprepare(vpu->mod_clk);
> +	clk_disable_unprepare(vpu->ahb_clk);

The device is not put back into reset here

Thanks!
Maxime

-- 
Maxime Ripard, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com

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