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

Jernej Škrabec
2019-03-16T11:23:47Z

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-gGgVlfcn5nU@public.gmane.org>
> > ---
> >
> > 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);