linux-kernel - Re: [PATCH v3 2/8] dmaengine: mmp_pdma: Add optional clock support

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Message-ID: <CAH1PCMZ7VbLxJbHQt4Ox_nO7yDSBMzTYiczC3FGBbG_oXgjLXw@mail.gmail.com>
Date: Fri, 15 Aug 2025 08:16:54 +0800
From: Guodong Xu <guodong@...cstar.com>
To: Yixun Lan <dlan@...too.org>
Cc: Vinod Koul <vkoul@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Duje Mihanović <duje.mihanovic@...le.hr>, 
	Philipp Zabel <p.zabel@...gutronix.de>, Paul Walmsley <paul.walmsley@...ive.com>, 
	Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
	Alexandre Ghiti <alex@...ti.fr>, Alex Elder <elder@...cstar.com>, 
	Vivian Wang <wangruikang@...as.ac.cn>, dmaengine@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-riscv@...ts.infradead.org, spacemit@...ts.linux.dev
Subject: Re: [PATCH v3 2/8] dmaengine: mmp_pdma: Add optional clock support

On Thu, Jul 24, 2025 at 8:31 PM Yixun Lan <dlan@...too.org> wrote:
>
> Hi Guodong,
>
> I personally find the word 'optional' introducing some confusions..
> I can understand from driver perspective, it's kind of optional,
> but from SpacemiT K1 perspective, it's mandatory for this driver
> (the 'clocks' property of DT is in 'required' section)
>
> feel free to improve the commit message, maybe add some motivation
> hehind this

Thanks Yixun for your advice. I will improve it.

-
Guodong

>
> On 17:39 Mon 14 Jul     , Guodong Xu wrote:
> > Add support for retrieving and enabling an optional clock during
> > mmp_pdma_probe().
> >
> > Signed-off-by: Guodong Xu <guodong@...cstar.com>
> > ---
> > v3: No change.
> > v2: No change.
> > ---
> >  drivers/dma/mmp_pdma.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/dma/mmp_pdma.c b/drivers/dma/mmp_pdma.c
> > index a95d31103d3063a1d11177a1a37b89ac2fd213e9..4a6dbf55823722d26cc69379d22aaa88fbe19313 100644
> > --- a/drivers/dma/mmp_pdma.c
> > +++ b/drivers/dma/mmp_pdma.c
> > @@ -15,6 +15,7 @@
> >  #include <linux/device.h>
> >  #include <linux/platform_data/mmp_dma.h>
> >  #include <linux/dmapool.h>
> > +#include <linux/clk.h>
> >  #include <linux/of_dma.h>
> >  #include <linux/of.h>
> >
> > @@ -1019,6 +1020,7 @@ static int mmp_pdma_probe(struct platform_device *op)
> >  {
> >       struct mmp_pdma_device *pdev;
> >       struct mmp_dma_platdata *pdata = dev_get_platdata(&op->dev);
> > +     struct clk *clk;
> >       int i, ret, irq = 0;
> >       int dma_channels = 0, irq_num = 0;
> >       const enum dma_slave_buswidth widths =
> > @@ -1037,6 +1039,10 @@ static int mmp_pdma_probe(struct platform_device *op)
> >       if (IS_ERR(pdev->base))
> >               return PTR_ERR(pdev->base);
> >
> > +     clk = devm_clk_get_optional_enabled(pdev->dev, NULL);
> > +     if (IS_ERR(clk))
> > +             return PTR_ERR(clk);
> > +
> >       if (pdev->dev->of_node) {
> >               /* Parse new and deprecated dma-channels properties */
> >               if (of_property_read_u32(pdev->dev->of_node, "dma-channels",
> >
> > --
> > 2.43.0
> >
>
> --
> Yixun Lan (dlan)