linux-kernel - Re: [PATCH 1/2] SPI: Add SPI driver for Sunplus SP7021

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Date:   Tue, 02 Nov 2021 15:31:09 +0100
From:   Philipp Zabel <p.zabel@...gutronix.de>
To:     "LH.Kuo" <lhjeff911@...il.com>, broonie@...nel.org,
        robh+dt@...nel.org, linux-spi@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     dvorkin@...bo.com, qinjian@...lus1.com, wells.lu@...plus.com,
        "LH.Kuo" <lh.kuo@...plus.com>
Subject: Re: [PATCH 1/2] SPI: Add SPI driver for Sunplus SP7021

On Mon, 2021-11-01 at 14:18 +0800, LH.Kuo wrote:
[...]
> +static int pentagram_spi_controller_probe(struct platform_device *pdev)
> +{
> +	struct resource *res;
> +	int ret;
> +	int mode;
> +	unsigned int max_freq;
> +	struct spi_controller *ctlr;
> +	struct pentagram_spi_master *pspim;
> +
> +	FUNC_DBG();

Drop these.

[...]
> +	/* clk*/
> +	pspim->spi_clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(pspim->spi_clk)) {
> +		dev_err(&pdev->dev, "devm_clk_get fail\n");
> +		goto free_alloc;
> +	}
> +	ret = clk_prepare_enable(pspim->spi_clk);

Move this and reset_control_deassert() as far back as possible.

> +	if (ret)
> +		goto free_alloc;
> +
> +	/* reset*/
> +	pspim->rstc = devm_reset_control_get(&pdev->dev, NULL);

Use devm_reset_control_get_exclusive() instead.
This should be done before clk_prepare_enable().

> +	dev_dbg(&pdev->dev, "pspim->rstc : 0x%x\n", (unsigned int)pspim->rstc);
> +	if (IS_ERR(pspim->rstc)) {
> +		ret = PTR_ERR(pspim->rstc);
> +		dev_err(&pdev->dev, "SPI failed to retrieve reset controller: %d\n", ret);
> +		goto free_clk;
> +	}
> +	ret = reset_control_deassert(pspim->rstc);

Same as the clock, I'd move this after the dma allocations.

> +	if (ret)
> +		goto free_clk;
> +
> +	/* dma alloc*/
> +	pspim->tx_dma_vir_base = dma_alloc_coherent(&pdev->dev, bufsiz,
> +					&pspim->tx_dma_phy_base, GFP_ATOMIC);

Consider using dmam_alloc_coherent, same for rx_dma_vir_base.

regards
Philipp