Re: [PATCH v2] [media] at91: add code to initialize and manage the ISI_MCK for Atmel ISI driver.

[Guennadi Liakhovetski <g.liakhovetski@gmx.de>]

On Tue, 6 Sep 2011, Josh Wu wrote:

> This patch enable the configuration for ISI_MCK, which is provided by programmable clock.
> 
> Signed-off-by: Josh Wu <josh.wu@atmel.com>
> ---
>  drivers/media/video/atmel-isi.c |   60 ++++++++++++++++++++++++++++++++++++++-
>  include/media/atmel-isi.h       |    4 ++
>  2 files changed, 63 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/media/video/atmel-isi.c b/drivers/media/video/atmel-isi.c
> index 7b89f00..768bf59 100644
> --- a/drivers/media/video/atmel-isi.c
> +++ b/drivers/media/video/atmel-isi.c
> @@ -90,7 +90,10 @@ struct atmel_isi {
>  	struct isi_dma_desc		dma_desc[MAX_BUFFER_NUM];
>  
>  	struct completion		complete;
> +	/* ISI peripherial clock */
>  	struct clk			*pclk;
> +	/* ISI_MCK, provided by PCK */
> +	struct clk			*mck;
>  	unsigned int			irq;
>  
>  	struct isi_platform_data	*pdata;
> @@ -763,6 +766,10 @@ static int isi_camera_add_device(struct soc_camera_device *icd)
>  	if (ret)
>  		return ret;
>  
> +	ret = clk_enable(isi->mck);
> +	if (ret)
> +		return ret;
> +

Don't you have to disable the pixel clock (isi->pclk), that you just have 
enabled above this hunk, on the above error path?

>  	isi->icd = icd;
>  	dev_dbg(icd->parent, "Atmel ISI Camera driver attached to camera %d\n",
>  		 icd->devnum);
> @@ -776,6 +783,7 @@ static void isi_camera_remove_device(struct soc_camera_device *icd)
>  
>  	BUG_ON(icd != isi->icd);
>  
> +	clk_disable(isi->mck);
>  	clk_disable(isi->pclk);
>  	isi->icd = NULL;
>  
> @@ -882,6 +890,49 @@ static struct soc_camera_host_ops isi_soc_camera_host_ops = {
>  };
>  
>  /* -----------------------------------------------------------------------*/
> +/* Initialize ISI_MCK clock, called by atmel_isi_probe() function */
> +static int initialize_mck(struct platform_device *pdev,
> +			struct atmel_isi *isi)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct isi_platform_data *pdata = dev->platform_data;
> +	struct clk *pck_parent;
> +	int ret;
> +
> +	if (!strlen(pdata->pck_name) || !strlen(pdata->pck_parent_name))
> +		return -EINVAL;
> +
> +	/* ISI_MCK is provided by PCK clock */
> +	isi->mck = clk_get(dev, pdata->pck_name);

I think, it's still not what Russell meant. Look at 
drivers/mmc/host/atmel-mci.c:

	host->mck = clk_get(&pdev->dev, "mci_clk");

and in arch/arm/mach-at91/at91sam9g45.c they've got

	CLKDEV_CON_DEV_ID("mci_clk", "atmel_mci.0", &mmc0_clk),
	CLKDEV_CON_DEV_ID("mci_clk", "atmel_mci.1", &mmc1_clk),

where

#define CLKDEV_CON_DEV_ID(_con_id, _dev_id, _clk)	\
	{						\
		.con_id = _con_id,			\
		.dev_id = _dev_id,			\
		.clk = _clk,				\
	}

I.e., in the device driver (mmc in this case) you only use the (platform) 
device instance, whose dev_name(dev) is then matched against one of clock 
lookups above, and a connection ID, which is used in case your device is 
using more than one clock. In the ISI case, your pck1 clock, that you seem 
to need here, doesn't have a clock lookup object, so, you might have to 
add one, and then use its connection ID.

> +	if (IS_ERR(isi->mck)) {
> +		dev_err(dev, "Failed to get PCK: %s\n", pdata->pck_name);
> +		return PTR_ERR(isi->mck);
> +	}
> +
> +	pck_parent = clk_get(dev, pdata->pck_parent_name);
> +	if (IS_ERR(pck_parent)) {
> +		ret = PTR_ERR(pck_parent);
> +		dev_err(dev, "Failed to get PCK parent: %s\n",
> +				pdata->pck_parent_name);
> +		goto err_init_mck;
> +	}
> +
> +	ret = clk_set_parent(isi->mck, pck_parent);

I'm not entirely sure on this one, but as we had a similar situation with 
clocks, we decided to extablish the clock hierarchy in the board code, and 
only deal with the actual device clocks in the driver itself. I.e., we 
moved all clk_set_parent() and setting up the parent clock into the board. 
And I do think, this makes more sense, than doing this in the driver, not 
all users of this driver will need to manage the parent clock, right?

> +	clk_put(pck_parent);
> +	if (ret)
> +		goto err_init_mck;
> +
> +	ret = clk_set_rate(isi->mck, pdata->isi_mck_hz);
> +	if (ret < 0)
> +		goto err_init_mck;
> +
> +	return 0;
> +
> +err_init_mck:
> +	clk_put(isi->mck);
> +	return ret;
> +}
> +
>  static int __devexit atmel_isi_remove(struct platform_device *pdev)
>  {
>  	struct soc_camera_host *soc_host = to_soc_camera_host(&pdev->dev);
> @@ -897,6 +948,7 @@ static int __devexit atmel_isi_remove(struct platform_device *pdev)
>  			isi->fb_descriptors_phys);
>  
>  	iounmap(isi->regs);
> +	clk_put(isi->mck);
>  	clk_put(isi->pclk);
>  	kfree(isi);
>  
> @@ -915,7 +967,8 @@ static int __devinit atmel_isi_probe(struct platform_device *pdev)
>  	struct isi_platform_data *pdata;
>  
>  	pdata = dev->platform_data;
> -	if (!pdata || !pdata->data_width_flags) {
> +	if (!pdata || !pdata->data_width_flags || !pdata->isi_mck_hz
> +			|| !pdata->pck_name || !pdata->pck_parent_name) {

These names you won't need either.

>  		dev_err(&pdev->dev,
>  			"No config available for Atmel ISI\n");
>  		return -EINVAL;
> @@ -944,6 +997,11 @@ static int __devinit atmel_isi_probe(struct platform_device *pdev)
>  	INIT_LIST_HEAD(&isi->video_buffer_list);
>  	INIT_LIST_HEAD(&isi->dma_desc_head);
>  
> +	/* Initialize ISI_MCK clock */
> +	ret = initialize_mck(pdev, isi);
> +	if (ret)
> +		goto err_alloc_descriptors;
> +
>  	isi->p_fb_descriptors = dma_alloc_coherent(&pdev->dev,
>  				sizeof(struct fbd) * MAX_BUFFER_NUM,
>  				&isi->fb_descriptors_phys,
> diff --git a/include/media/atmel-isi.h b/include/media/atmel-isi.h
> index 26cece5..dcbb822 100644
> --- a/include/media/atmel-isi.h
> +++ b/include/media/atmel-isi.h
> @@ -114,6 +114,10 @@ struct isi_platform_data {
>  	u32 data_width_flags;
>  	/* Using for ISI_CFG1 */
>  	u32 frate;
> +	/* Using for ISI_MCK, provided by PCK */
> +	u32 isi_mck_hz;
> +	const char *pck_name;
> +	const char *pck_parent_name;
>  };
>  
>  #endif /* __ATMEL_ISI_H__ */
> -- 
> 1.6.3.3
> 

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/