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Message-ID: <4C79549CB6F772498162A641D92D532802CC5FEC@penmb01.corp.atmel.com>
Date: Thu, 22 Sep 2011 11:23:54 +0800
From: "Wu, Josh" <Josh.wu@...el.com>
To: "Ferre, Nicolas" <Nicolas.FERRE@...el.com>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-media@...r.kernel.org>
Cc: "Guennadi Liakhovetski" <g.liakhovetski@....de>,
<plagnioj@...osoft.com>, <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v2] [media] at91: add code to initialize and manage the ISI_MCK for Atmel ISI driver.
Hi, Nicolas
On Friday, September 09, 2011 6:05 PM, Nicolas Ferre wrote:
> 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@...el.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
> [..]
>>> /*
>>> ---------------------------------------------------------------------
>>> --*/
>>> +/* 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...
According to sam9g20_wm8731.c file, and combined Guennadi and J.C's advices, I'd like to only add clk_set_rate() and enable/disble isi_mck code in ISI driver.
Also I will define isi_mck clock in soc chip file(at91sam9g45.c).
Then I will move all setting up the parent clock code into the at91sam9g45_devices.c, where there are code to add Atmel ISI device.
I will generate the new version patch for it soon.
>>> + 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
Best Regards,
Josh Wu
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