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

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Date:   Sun, 24 Oct 2021 19:23:33 +0530
From:   Bhupesh Sharma <bhupesh.sharma@...aro.org>
To:     Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>
Cc:     MSM <linux-arm-msm@...r.kernel.org>, linux-crypto@...r.kernel.org,
        bhupesh.linux@...il.com,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Andy Gross <agross@...nel.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S . Miller" <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 Vladimir,

On Thu, 14 Oct 2021 at 00:46, Vladimir Zapolskiy
<vladimir.zapolskiy@...aro.org> wrote:
>
> 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.

Thanks, I will fix this in the v5.

Regards,
Bhupesh

> > +
> > +     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