Le 06/09/2011 08:54, Guennadi Liakhovetski :
> 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@xxxxxxxxx>
>> ---
>> 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
[..]
>> /* -----------------------------------------------------------------------*/
>> +/* 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?
Exactly.
Josh, for the two comments by Guennadi above, you can take
sound/soc/atmel/sam9g20_wm8731.c
as an example of using PCK and parent clocks. You will also find how to
use named clocks and how to set the programmable clocks rate...
>> + 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);
[..]
Best regards,
--
Nicolas Ferre
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