linux-kernel - Re: [RFC PATCH 5/5] mtd: hyperbus: Add driver for TI's Hyperbus memory controller

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Date:   Mon, 25 Feb 2019 19:29:17 +0300
From:   Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:     "Vignesh R (by way of Boris Brezillon <bbrezillon@...nel.org>)" 
        <vigneshr@...com>, David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Boris Brezillon <bbrezillon@...nel.org>,
        Marek Vasut <marek.vasut@...il.com>,
        Richard Weinberger <richard@....at>,
        Rob Herring <robh+dt@...nel.org>
Cc:     devicetree@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
        tudor.ambarus@...rochip.com,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        nsekhar@...com, linux-kernel@...r.kernel.org,
        linux-mtd@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC PATCH 5/5] mtd: hyperbus: Add driver for TI's Hyperbus
 memory controller

Hello!

On 02/19/2019 09:36 AM, Vignesh R (by way of Boris Brezillon <bbrezillon@...nel.org>) wrote:

> Add driver for Hyperbus memory controller on TI's AM654 SoC. Programming
> IP is pretty simple and provides direct memory mapped access to
> connected Flash devices.

   Are you sure you posted the _complete_ driver?

> Add basic support for the IP without DMA. Second ChipSelect is not
> supported for now.
> 
> Signed-off-by: Vignesh R <vigneshr@...com>
> ---
>  drivers/mtd/hyperbus/hbmc_am654.c | 105 ++++++++++++++++++++++++++++++
>  1 file changed, 105 insertions(+)
>  create mode 100644 drivers/mtd/hyperbus/hbmc_am654.c
> 
> diff --git a/drivers/mtd/hyperbus/hbmc_am654.c b/drivers/mtd/hyperbus/hbmc_am654.c
> new file mode 100644
> index 000000000000..1f0d2dc52f9f
> --- /dev/null
> +++ b/drivers/mtd/hyperbus/hbmc_am654.c
> @@ -0,0 +1,105 @@
[...]
> +static int am654_hbmc_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct am654_hbmc_priv *priv;
> +	struct resource *res;
> +	int err;
> +
> +	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, priv);
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (IS_ERR(res)) {
> +		dev_err(&pdev->dev, "failed to get memory resource\n");
> +		return -ENOENT;
> +	}
> +
> +	priv->regbase = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(priv->regbase)) {
> +		dev_err(dev, "Cannot remap controller address.\n");
> +		return PTR_ERR(priv->regbase);
> +	}
> +
> +	pm_runtime_enable(&pdev->dev);
> +	err = pm_runtime_get_sync(&pdev->dev);

   That's all nice but where's the code that accesses the actual registers?

> +	if (err < 0) {
> +		pm_runtime_put_noidle(&pdev->dev);

   Calling "put" with previously failed "get" sees strange...

> +		return err;
> +	}
> +
> +	priv->hbdev.needs_calib = true;
> +	priv->hbdev.dev = &pdev->dev;
> +	priv->hbdev.np = of_get_next_child(dev->of_node, NULL);
> +	err = hb_register_device(&priv->hbdev);
> +	if (err) {
> +		dev_err(&pdev->dev, "failed to register controller\n");
> +		goto err_destroy;
> +	}
> +
> +	return 0;
> +
> +err_destroy:
> +	hb_unregister_device(&priv->hbdev);

   Calling "unregister" with "register" previously failed also looks strange...

> +	pm_runtime_put_sync(&pdev->dev);

   Why the sync() version?

> +	return err;
> +}
[...]

MBR, Sergei