linux-kernel - Re: [PATCH] media: davinci: vpif: add check for NULL handler

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Date:	Fri, 17 Aug 2012 14:02:19 +0530
From:	Prabhakar Lad <prabhakar.lad@...com>
To:	Sekhar Nori <nsekhar@...com>
CC:	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	<davinci-linux-open-source@...ux.davincidsp.com>,
	<linux-kernel@...r.kernel.org>,
	Mauro Carvalho Chehab <mchehab@...radead.org>,
	Hans Verkuil <hans.verkuil@...co.com>,
	LMML <linux-media@...r.kernel.org>,
	Manjunath Hadli <manjunath.hadli@...com>
Subject: Re: [PATCH] media: davinci: vpif: add check for NULL handler

Hi Sekhar,

On Friday 17 August 2012 11:07 AM, Sekhar Nori wrote:
> On 8/17/2012 10:51 AM, Prabhakar Lad wrote:
>> Hi Laurent,
>>
>> Thanks for the review.
>>
>> On Thursday 16 August 2012 08:43 PM, Laurent Pinchart wrote:
>>> Hi Prabhakar,
>>>
>>> Thanks for the patch.
>>>
>>> On Thursday 16 August 2012 19:32:00 Prabhakar Lad wrote:
>>>> From: Lad, Prabhakar <prabhakar.lad@...com>
>>>>
>>>> Signed-off-by: Lad, Prabhakar <prabhakar.lad@...com>
>>>> Signed-off-by: Manjunath Hadli <manjunath.hadli@...com>
>>>> Cc: Hans Verkuil <hans.verkuil@...co.com>
>>>> ---
>>>>  drivers/media/video/davinci/vpif_capture.c |   12 +++++++-----
>>>>  drivers/media/video/davinci/vpif_display.c |   14 ++++++++------
>>>>  2 files changed, 15 insertions(+), 11 deletions(-)
>>>>
>>>> diff --git a/drivers/media/video/davinci/vpif_capture.c
>>>> b/drivers/media/video/davinci/vpif_capture.c index 266025e..a87b7a5 100644
>>>> --- a/drivers/media/video/davinci/vpif_capture.c
>>>> +++ b/drivers/media/video/davinci/vpif_capture.c
>>>> @@ -311,12 +311,14 @@ static int vpif_start_streaming(struct vb2_queue *vq,
>>>> unsigned int count) }
>>>>
>>>>  	/* configure 1 or 2 channel mode */
>>>> -	ret = vpif_config_data->setup_input_channel_mode
>>>> -					(vpif->std_info.ycmux_mode);
>>>> +	if (vpif_config_data->setup_input_channel_mode) {
>>>> +		ret = vpif_config_data->setup_input_channel_mode
>>>> +						(vpif->std_info.ycmux_mode);
>>>>
>>>> -	if (ret < 0) {
>>>> -		vpif_dbg(1, debug, "can't set vpif channel mode\n");
>>>> -		return ret;
>>>> +		if (ret < 0) {
>>>> +			vpif_dbg(1, debug, "can't set vpif channel mode\n");
>>>> +			return ret;
>>>> +		}
>>>
>>> This change looks good to me. However, note that you will need to get rid of 
>>> board code callbacks at some point to implement device tree support. It would 
>>> be worth thinking about how to do so now.
>>>
>> Currently VPIF driver is only used by dm646x, and the handlers for this
>> in the the board code are not null. This patch is intended for da850
>> where this handlers will be null.
>>
>>>>  	}
>>>>
>>>>  	/* Call vpif_set_params function to set the parameters and addresses */
>>>> diff --git a/drivers/media/video/davinci/vpif_display.c
>>>> b/drivers/media/video/davinci/vpif_display.c index e129c98..1e35f92 100644
>>>> --- a/drivers/media/video/davinci/vpif_display.c
>>>> +++ b/drivers/media/video/davinci/vpif_display.c
>>>> @@ -280,12 +280,14 @@ static int vpif_start_streaming(struct vb2_queue *vq,
>>>> unsigned int count) }
>>>>
>>>>  	/* clock settings */
>>>> -	ret =
>>>> -	    vpif_config_data->set_clock(ch->vpifparams.std_info.ycmux_mode,
>>>> -					ch->vpifparams.std_info.hd_sd);
>>>> -	if (ret < 0) {
>>>> -		vpif_err("can't set clock\n");
>>>> -		return ret;
>>>> +	if (vpif_config_data->set_clock) {
>>>
>>> Does the DaVinci platform use the common clock framework ? If so, a better fix 
>>> for this would be to pass a clock name through platform data instead of using 
>>> a callback function.
>>>
>> Currently DaVinci is not using the common clock framework.
>>
>> Can you ACK this patch?
> 
> Yes, DaVinci has not migrated to common clock framework (yet). However,
> even without that it should be possible to use clock API in driver code.
> Using a callback to enable clocks or even passing the clock name from
> platform data would be bypassing an existing framework. Clock name
> should be IP specific, so it should be possible to use that in driver.
> 
The callback is not actually dealing with PSC clock's but with system
module registers.

Thx,
--Prabhakar

> Thanks,
> Sekhar
> 

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