linux-kernel - Re: [PATCH 1/3] media: atmel-isc: Not support RBG format from sensor.

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Date:   Thu, 24 Aug 2017 14:25:12 +0800
From:   "Yang, Wenyou" <Wenyou.Yang@...rochip.com>
To:     Hans Verkuil <hverkuil@...all.nl>, <mchehab@...pensource.com>
CC:     <Nicolas.Ferre@...rochip.com>, <linux-kernel@...r.kernel.org>,
        <sakari.ailus@....fi>, <corbet@....net>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-media@...r.kernel.org>
Subject: Re: [PATCH 1/3] media: atmel-isc: Not support RBG format from sensor.



On 2017/8/23 18:37, Hans Verkuil wrote:
> On 08/22/17 09:30, Wenyou.Yang@...rochip.com wrote:
>> Hi Hans,
>>
>>> -----Original Message-----
>>> From: Hans Verkuil [mailto:hverkuil@...all.nl]
>>> Sent: 2017年8月22日 15:00
>>> To: Wenyou Yang - A41535 <Wenyou.Yang@...rochip.com>; Mauro Carvalho
>>> Chehab <mchehab@...pensource.com>
>>> Cc: Nicolas Ferre - M43238 <Nicolas.Ferre@...rochip.com>; linux-
>>> kernel@...r.kernel.org; Sakari Ailus <sakari.ailus@....fi>; Jonathan Corbet
>>> <corbet@....net>; linux-arm-kernel@...ts.infradead.org; Linux Media Mailing List
>>> <linux-media@...r.kernel.org>
>>> Subject: Re: [PATCH 1/3] media: atmel-isc: Not support RBG format from sensor.
>>>
>>> On 08/22/2017 03:18 AM, Yang, Wenyou wrote:
>>>> Hi Hans,
>>>>
>>>> On 2017/8/21 22:07, Hans Verkuil wrote:
>>>>> On 08/17/2017 09:16 AM, Wenyou Yang wrote:
>>>>>> The 12-bit parallel interface supports the Raw Bayer, YCbCr,
>>>>>> Monochrome and JPEG Compressed pixel formats from the external
>>>>>> sensor, not support RBG pixel format.
>>>>>>
>>>>>> Signed-off-by: Wenyou Yang <wenyou.yang@...rochip.com>
>>>>>> ---
>>>>>>
>>>>>>    drivers/media/platform/atmel/atmel-isc.c | 5 +++++
>>>>>>    1 file changed, 5 insertions(+)
>>>>>>
>>>>>> diff --git a/drivers/media/platform/atmel/atmel-isc.c
>>>>>> b/drivers/media/platform/atmel/atmel-isc.c
>>>>>> index d4df3d4ccd85..535bb03783fe 100644
>>>>>> --- a/drivers/media/platform/atmel/atmel-isc.c
>>>>>> +++ b/drivers/media/platform/atmel/atmel-isc.c
>>>>>> @@ -1478,6 +1478,11 @@ static int isc_formats_init(struct isc_device *isc)
>>>>>>    	while (!v4l2_subdev_call(subdev, pad, enum_mbus_code,
>>>>>>    	       NULL, &mbus_code)) {
>>>>>>    		mbus_code.index++;
>>>>>> +
>>>>>> +		/* Not support the RGB pixel formats from sensor */
>>>>>> +		if ((mbus_code.code & 0xf000) == 0x1000)
>>>>>> +			continue;
>>>>> Am I missing something? Here you skip any RGB mediabus formats, but
>>>>> in patch 3/3 you add RGB mediabus formats. But this patch prevents
>>>>> those new formats from being selected, right?
>>>> This patch prevents getting the RGB format from the sensor directly.
>>>> The RGB format can be produced by ISC controller by itself.
>>> OK, I think I see what is going on here. The isc_formats array really is two arrays
>>> in one: up to RAW_FMT_IND_END it describes what it can receive from the
>>> source, and after that it describes what it can convert it to.
>> Not exactly.
>>
>> Yes, up to RAW_FMT_IND_END, these formats must be got from the senor, they are RAW formats.
>>  From ISC_FMT_IND_START to ISC_FMT_IND_END, they can be generated by the ISC controller.
>> It is possible they can be got from the sensor too, the driver will check it.
>> If it can be got from both the sensor and the ISC controller, the user can use the "sensor_preferred" parameter to decide from which one to get.
>> The RBG formats are the exception.
>>
>>> But if you can't handle RGB formats from the sensor, then why not make sure
>>> none of the mbus codes in isc_formats uses RGB? That makes much more sense.
>>>
>>> E.g.:
>>>
>>>          { V4L2_PIX_FMT_RGB565, MEDIA_BUS_FMT_RGB565_2X8_LE, 16,
>>>            ISC_PFE_CFG0_BPS_EIGHT, ISC_BAY_CFG_BGBG,
>>> ISC_RLP_CFG_MODE_RGB565,
>>>            ISC_DCFG_IMODE_PACKED16, ISC_DCTRL_DVIEW_PACKED, 0x7b,
>>>            false, false },
>>>
>>> Why use MEDIA_BUS_FMT_RGB565_2X8_LE if this apparently is not supported?
>> This array is also the lists of all formats supported by the ISC(including got from the sensor).
>> The RGB formats are only generated by the ISC controller, not from the sensor.
> You're adding code that skips any entries of the table where mbus_code is an
> RGB code. But this can also be done by not having RGB mbus codes in the table
> in the first place since they make no sense if the HW cannot handle that!
> Set the mbus_code to e.g. 0 for such entries, that makes more sense.
>
> I also strongly suggest changing how the table is organized since those
> _FMT_IND_ indices are all to easy to get wrong (and frankly hard to understand).
Yes, you are right, I will change it. Do you have some advice?

Thank you.

>
> Regards,
>
> 	Hans
>
>>> Regards,
>>>
>>> 	Hans
>>>
>>>>> Regards,
>>>>>
>>>>> 	Hans
>>>>>
>>>>>> +
>>>>>>    		fmt = find_format_by_code(mbus_code.code, &i);
>>>>>>    		if (!fmt)
>>>>>>    			continue;
>>>>>>
>>>> Best Regards,
>>>> Wenyou Yang
>>>>
>> Best Regards,
>> Wenyou Yang
Best Regards,
Wenyou Yang