linux-kernel - Re: [PATCH] dmaengine: qcom: bam_dma: make channels/EEs optional in DT with clock

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Date:   Thu, 18 May 2023 16:43:57 +0530
From:   Bhupesh Sharma <bhupesh.sharma@...aro.org>
To:     Stephan Gerhold <stephan@...hold.net>
Cc:     Vinod Koul <vkoul@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Andy Gross <agross@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        linux-arm-msm@...r.kernel.org, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dmaengine: qcom: bam_dma: make channels/EEs optional in
 DT with clock

Hi Stephan,

On Thu, 18 May 2023 at 14:56, Stephan Gerhold <stephan@...hold.net> wrote:
>
> If we have a BAM clock in the DT we are able to turn on the BAM
> controller while probing, so there is no need to read "num-channels"
> and "qcom,num-ees" from the DT. It can be read more accurately directly
> from the identification registers of the BAM.
>
> This simplifies setting up typical controlled-remotely BAM DMAs in the
> DT that can be turned on via a clock (e.g. the BLSP DMA).

Can you please list which qcom board(s) you tested this patch on?

Thanks,
Bhupesh

> Signed-off-by: Stephan Gerhold <stephan@...hold.net>
> ---
>  drivers/dma/qcom/bam_dma.c | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c
> index 1e47d27e1f81..4c3eb972039d 100644
> --- a/drivers/dma/qcom/bam_dma.c
> +++ b/drivers/dma/qcom/bam_dma.c
> @@ -1272,7 +1272,15 @@ static int bam_dma_probe(struct platform_device *pdev)
>         bdev->powered_remotely = of_property_read_bool(pdev->dev.of_node,
>                                                 "qcom,powered-remotely");
>
> -       if (bdev->controlled_remotely || bdev->powered_remotely) {
> +       if (bdev->controlled_remotely || bdev->powered_remotely)
> +               bdev->bamclk = devm_clk_get_optional(bdev->dev, "bam_clk");
> +       else
> +               bdev->bamclk = devm_clk_get(bdev->dev, "bam_clk");
> +
> +       if (IS_ERR(bdev->bamclk))
> +               return PTR_ERR(bdev->bamclk);
> +
> +       if (!bdev->bamclk) {
>                 ret = of_property_read_u32(pdev->dev.of_node, "num-channels",
>                                            &bdev->num_channels);
>                 if (ret)
> @@ -1284,14 +1292,6 @@ static int bam_dma_probe(struct platform_device *pdev)
>                         dev_err(bdev->dev, "num-ees unspecified in dt\n");
>         }
>
> -       if (bdev->controlled_remotely || bdev->powered_remotely)
> -               bdev->bamclk = devm_clk_get_optional(bdev->dev, "bam_clk");
> -       else
> -               bdev->bamclk = devm_clk_get(bdev->dev, "bam_clk");
> -
> -       if (IS_ERR(bdev->bamclk))
> -               return PTR_ERR(bdev->bamclk);
> -
>         ret = clk_prepare_enable(bdev->bamclk);
>         if (ret) {
>                 dev_err(bdev->dev, "failed to prepare/enable clock\n");
>
> ---
> base-commit: 1c677f238f92ba0a329b7c13220f38b396872806
> change-id: 20230518-bamclk-dt-d44bae47b337
>
> Best regards,
> --
> Stephan Gerhold <stephan@...hold.net>
>