linux-kernel - Re: [PATCH v4 13/20] dma: qcom: bam_dma: Add support to initialize interconnect path

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Date:   Wed, 13 Oct 2021 22:15:39 +0300
From:   Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>
To:     Bhupesh Sharma <bhupesh.sharma@...aro.org>,
        linux-arm-msm@...r.kernel.org, linux-crypto@...r.kernel.org
Cc:     bhupesh.linux@...il.com, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, robh+dt@...nel.org, agross@...nel.org,
        herbert@...dor.apana.org.au, davem@...emloft.net,
        Thara Gopinath <thara.gopinath@...aro.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>
Subject: Re: [PATCH v4 13/20] dma: qcom: bam_dma: Add support to initialize
 interconnect path

Hi Bhupesh, Thara,

On 10/13/21 1:55 PM, Bhupesh Sharma wrote:
> From: Thara Gopinath <thara.gopinath@...aro.org>
> 
> BAM dma engine associated with certain hardware blocks could require
> relevant interconnect pieces be initialized prior to the dma engine
> initialization. For e.g. crypto bam dma engine on sm8250. Such requirement
> is passed on to the bam dma driver from dt via the "interconnects"
> property.  Add support in bam_dma driver to check whether the interconnect
> path is accessible/enabled prior to attempting driver intializations.
> 
> Cc: Bjorn Andersson <bjorn.andersson@...aro.org>
> Cc: Rob Herring <robh+dt@...nel.org>
> Signed-off-by: Bhupesh Sharma <bhupesh.sharma@...aro.org>
> [Make header file inclusion alphabetical]
> Signed-off-by: Thara Gopinath <thara.gopinath@...aro.org>
> ---
>   drivers/dma/qcom/bam_dma.c | 16 +++++++++++++++-
>   1 file changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c
> index c8a77b428b52..fc84ef42507d 100644
> --- a/drivers/dma/qcom/bam_dma.c
> +++ b/drivers/dma/qcom/bam_dma.c
> @@ -26,6 +26,7 @@
>   #include <linux/kernel.h>
>   #include <linux/io.h>
>   #include <linux/init.h>
> +#include <linux/interconnect.h>
>   #include <linux/slab.h>
>   #include <linux/module.h>
>   #include <linux/interrupt.h>
> @@ -392,6 +393,7 @@ struct bam_device {
>   	const struct reg_offset_data *layout;
>   
>   	struct clk *bamclk;
> +	struct icc_path *mem_path;
>   	int irq;
>   
>   	/* dma start transaction tasklet */
> @@ -1284,9 +1286,18 @@ static int bam_dma_probe(struct platform_device *pdev)
>   		return ret;
>   	}
>   
> +	/* Ensure that interconnects are initialized */
> +	bdev->mem_path = of_icc_get(bdev->dev, "memory");

I suppose devm_of_icc_get() usage could leave the error path and
bam_dma_remove() intact.

> +
> +	if (IS_ERR(bdev->mem_path)) {
> +		ret = PTR_ERR(bdev->mem_path);
> +		dev_err(bdev->dev, "failed to acquire icc path %d\n", ret);
> +		goto err_disable_clk;
> +	}
> +
>   	ret = bam_init(bdev);
>   	if (ret)
> -		goto err_disable_clk;
> +		goto err_icc_path_put;
>   
>   	tasklet_setup(&bdev->task, dma_tasklet);
>   
> @@ -1371,6 +1382,8 @@ static int bam_dma_probe(struct platform_device *pdev)
>   		tasklet_kill(&bdev->channels[i].vc.task);
>   err_tasklet_kill:
>   	tasklet_kill(&bdev->task);
> +err_icc_path_put:
> +	icc_put(bdev->mem_path);
>   err_disable_clk:
>   	clk_disable_unprepare(bdev->bamclk);
>   
> @@ -1406,6 +1419,7 @@ static int bam_dma_remove(struct platform_device *pdev)
>   
>   	tasklet_kill(&bdev->task);
>   
> +	icc_put(bdev->mem_path);
>   	clk_disable_unprepare(bdev->bamclk);
>   
>   	return 0;
> 

--
Best wishes,
Vladimir