linux-kernel - Re: [PATCH 2/6] dmaengine: sun6i: Add a quirk for additional mbus clock

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Date:   Sat, 16 Mar 2019 12:23:47 +0100
From:   Jernej Škrabec <jernej.skrabec@...l.net>
To:     Vinod Koul <vkoul@...nel.org>
Cc:     maxime.ripard@...tlin.com, wens@...e.org, robh+dt@...nel.org,
        mark.rutland@....com, dan.j.williams@...el.com,
        dmaengine@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-sunxi@...glegroups.com
Subject: Re: [PATCH 2/6] dmaengine: sun6i: Add a quirk for additional mbus clock

Hi!

Dne sobota, 16. marec 2019 ob 12:07:53 CET je Vinod Koul napisal(a):
> On 07-03-19, 17:58, Jernej Skrabec wrote:
> > H6 DMA controller needs additional mbus clock to be enabled.
> > 
> > Add a quirk for it and handle it accordingly.
> > 
> > Signed-off-by: Jernej Skrabec <jernej.skrabec@...l.net>
> > ---
> > 
> >  drivers/dma/sun6i-dma.c | 23 ++++++++++++++++++++++-
> >  1 file changed, 22 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
> > index 0cd13f17fc11..761555080325 100644
> > --- a/drivers/dma/sun6i-dma.c
> > +++ b/drivers/dma/sun6i-dma.c
> > @@ -129,6 +129,7 @@ struct sun6i_dma_config {
> > 
> >  	u32 dst_burst_lengths;
> >  	u32 src_addr_widths;
> >  	u32 dst_addr_widths;
> > 
> > +	bool mbus_clk;
> > 
> >  };
> >  
> >  /*
> > 
> > @@ -182,6 +183,7 @@ struct sun6i_dma_dev {
> > 
> >  	struct dma_device	slave;
> >  	void __iomem		*base;
> >  	struct clk		*clk;
> > 
> > +	struct clk		*clk_mbus;
> 
> So rather than have mbus_clk and then a ptr, why not use the ptr and use
> NULL value to check for..?
> 

I'm not sure what you mean here. clk_mbus will hold a reference to a clock 
retrieved by devm_clk_get() so it has to be "struct clk *".

What I'm missing here?

> >  	int			irq;
> >  	spinlock_t		lock;
> >  	struct reset_control	*rstc;
> > 
> > @@ -1208,6 +1210,14 @@ static int sun6i_dma_probe(struct platform_device
> > *pdev)> 
> >  		return PTR_ERR(sdc->clk);
> >  	
> >  	}
> > 
> > +	if (sdc->cfg->mbus_clk) {
> 
> where is the populated? I was expecting this to be set based on DT!

Of course it is based on DT. Check patch 5, where quirks structure attached to 
H6 DMA compatible contains ".mbus_clk = true,". "sdc->cfg" points to this 
quirk structure.

> 
> > +		sdc->clk_mbus = devm_clk_get(&pdev->dev, "mbus");
> > +		if (IS_ERR(sdc->clk_mbus)) {
> > +			dev_err(&pdev->dev, "No mbus clock 
specified\n");
> > +			return PTR_ERR(sdc->clk_mbus);
> > +		}
> > +	}
> > +
> > 
> >  	sdc->rstc = devm_reset_control_get(&pdev->dev, NULL);
> >  	if (IS_ERR(sdc->rstc)) {
> >  	
> >  		dev_err(&pdev->dev, "No reset controller specified\n");
> > 
> > @@ -1312,11 +1322,19 @@ static int sun6i_dma_probe(struct platform_device
> > *pdev)> 
> >  		goto err_reset_assert;
> >  	
> >  	}
> > 
> > +	if (sdc->cfg->mbus_clk) {
> > +		ret = clk_prepare_enable(sdc->clk_mbus);
> > +		if (ret) {
> > +			dev_err(&pdev->dev, "Couldn't enable mbus 
clock\n");
> > +			goto err_clk_disable;
> > +		}
> > +	}
> > +
> > 
> >  	ret = devm_request_irq(&pdev->dev, sdc->irq, sun6i_dma_interrupt, 
0,
> >  	
> >  			       dev_name(&pdev->dev), sdc);
> >  	
> >  	if (ret) {
> >  	
> >  		dev_err(&pdev->dev, "Cannot request IRQ\n");
> > 
> > -		goto err_clk_disable;
> > +		goto err_mbus_clk_disable;
> > 
> >  	}
> >  	
> >  	ret = dma_async_device_register(&sdc->slave);
> > 
> > @@ -1341,6 +1359,8 @@ static int sun6i_dma_probe(struct platform_device
> > *pdev)> 
> >  	dma_async_device_unregister(&sdc->slave);
> >  
> >  err_irq_disable:
> >  	sun6i_kill_tasklet(sdc);
> > 
> > +err_mbus_clk_disable:
> > +	clk_disable_unprepare(sdc->clk_mbus);
> > 
> >  err_clk_disable:
> >  	clk_disable_unprepare(sdc->clk);
> >  
> >  err_reset_assert:
> > @@ -1359,6 +1379,7 @@ static int sun6i_dma_remove(struct platform_device
> > *pdev)> 
> >  	sun6i_kill_tasklet(sdc);
> > 
> > +	clk_disable_unprepare(sdc->clk_mbus);
> > 
> >  	clk_disable_unprepare(sdc->clk);
> >  	reset_control_assert(sdc->rstc);