Subject: [PATCH] dmaengine:sirf:take clock and enable it while probing

From: [email-masked] (Vinod Koul)
Date: Thu, 21 Mar 2013 15:37:16 +0530

On Mon, Mar 18, 2013 at 04:33:43PM +0800, Barry Song wrote:
> From: Barry Song <[email-masked]>
> 
> there is hardcode which enabled the clock of dmaengine before,
> this patch takes the clock by standard clock API and enable it
> in probe.
> 
> Signed-off-by: Barry Song <[email-masked]>
> ---
>  drivers/dma/sirf-dma.c |   11 +++++++++++
>  1 files changed, 11 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/dma/sirf-dma.c b/drivers/dma/sirf-dma.c
> index 1d627e2..c439529 100644
> --- a/drivers/dma/sirf-dma.c
> +++ b/drivers/dma/sirf-dma.c
> @@ -16,6 +16,7 @@
>  #include <linux/of_address.h>
>  #include <linux/of_device.h>
>  #include <linux/of_platform.h>
> +#include <linux/clk.h>
>  #include <linux/sirfsoc_dma.h>
>  
>  #include "dmaengine.h"
> @@ -78,6 +79,7 @@ struct sirfsoc_dma {
>  	struct sirfsoc_dma_chan		channels[SIRFSOC_DMA_CHANNELS];
>  	void __iomem			*base;
>  	int				irq;
> +	struct clk			*clk;
>  	bool				is_marco;
>  };
>  
> @@ -639,6 +641,12 @@ static int sirfsoc_dma_probe(struct platform_device *op)
>  		return -EINVAL;
>  	}
>  
> +	sdma->clk = devm_clk_get(dev, NULL);
NULL? Arent you supposed to send a avlid non global string with. It may work now
but do you really want to go that path?

> +	if (IS_ERR(sdma->clk)) {
> +		dev_err(dev, "failed to get a clock.\n");
> +		return PTR_ERR(sdma->clk);
> +	}
> +
>  	ret = of_address_to_resource(dn, 0, &res);
>  	if (ret) {
>  		dev_err(dev, "Error parsing memory region!\n");
> @@ -698,6 +706,8 @@ static int sirfsoc_dma_probe(struct platform_device *op)
>  
>  	tasklet_init(&sdma->tasklet, sirfsoc_dma_tasklet, (unsigned long)sdma);
>  
> +	clk_prepare_enable(sdma->clk);
shouldnt you be enabling clock when you start a txn. Keeping clock on in probe
doesnt seem too smart

> +
>  	/* Register DMA engine */
>  	dev_set_drvdata(dev, sdma);
>  	ret = dma_async_device_register(dma);
> @@ -720,6 +730,7 @@ static int sirfsoc_dma_remove(struct platform_device *op)
>  	struct device *dev = &op->dev;
>  	struct sirfsoc_dma *sdma = dev_get_drvdata(dev);
>  
> +	clk_disable_unprepare(sdma->clk);
>  	dma_async_device_unregister(&sdma->dma);
>  	free_irq(sdma->irq, sdma);
>  	irq_dispose_mapping(sdma->irq);
> -- 
> 1.7.5.4
> 
> 
> 
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