linux-kernel - Re: [PATCH 4/7] spi: spi-geni-qcom: Add support for GPI dma

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Date:   Tue, 12 Jan 2021 08:31:52 +0100
From:   Lukas Wunner <lukas@...ner.de>
To:     Vinod Koul <vkoul@...nel.org>
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Mark Brown <broonie@...nel.org>, Wolfram Sang <wsa@...nel.org>,
        linux-arm-msm@...r.kernel.org, Andy Gross <agross@...nel.org>,
        Matthias Kaehlcke <mka@...omium.org>,
        Douglas Anderson <dianders@...omium.org>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Amit Pundir <amit.pundir@...aro.org>,
        linux-spi@...r.kernel.org, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/7] spi: spi-geni-qcom: Add support for GPI dma

On Mon, Jan 11, 2021 at 08:46:48PM +0530, Vinod Koul wrote:
> @@ -328,8 +609,34 @@ static int spi_geni_init(struct spi_geni_master *mas)
>  	spi_tx_cfg &= ~CS_TOGGLE;
>  	writel(spi_tx_cfg, se->base + SE_SPI_TRANS_CFG);
>  
> +	mas->tx = dma_request_slave_channel(mas->dev, "tx");
> +	if (IS_ERR_OR_NULL(mas->tx)) {
> +		dev_err(mas->dev, "Failed to get tx DMA ch %ld", PTR_ERR(mas->tx));
> +		ret = PTR_ERR(mas->tx);
> +		goto out_pm;
> +	} else {
> +		mas->rx = dma_request_slave_channel(mas->dev, "rx");
> +		if (IS_ERR_OR_NULL(mas->rx)) {
> +			dev_err(mas->dev, "Failed to get rx DMA ch %ld", PTR_ERR(mas->rx));
> +			dma_release_channel(mas->tx);
> +			ret = PTR_ERR(mas->rx);
> +			goto out_pm;
> +		}

These channels need to be released in spi_geni_remove().

Also, you may want to fall back to PIO mode if channel allocation fails.

Thanks,

Lukas