On 06/22/2015 09:21 AM, Guennadi Liakhovetski wrote:
> Hi Hans,
>
> On Mon, 22 Jun 2015, Hans Verkuil wrote:
>
>> On 06/21/2015 07:23 PM, Guennadi Liakhovetski wrote:
>>> On Mon, 15 Jun 2015, Hans Verkuil wrote:
>>>
>>>> From: Hans Verkuil <hans.verkuil@xxxxxxxxx>
>>>>
>>>> When the standard changes the VACTIVE and VDELAY values need to be updated.
>>>>
>>>> Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
>>>> ---
>>>> drivers/media/i2c/soc_camera/tw9910.c | 29 ++++++++++++++++++++++++++++-
>>>> 1 file changed, 28 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/media/i2c/soc_camera/tw9910.c b/drivers/media/i2c/soc_camera/tw9910.c
>>>> index df66417..e939c24 100644
>>>> --- a/drivers/media/i2c/soc_camera/tw9910.c
>>>> +++ b/drivers/media/i2c/soc_camera/tw9910.c
>>>> @@ -510,13 +510,39 @@ static int tw9910_s_std(struct v4l2_subdev *sd, v4l2_std_id norm)
>>>> {
>>>> struct i2c_client *client = v4l2_get_subdevdata(sd);
>>>> struct tw9910_priv *priv = to_tw9910(client);
>>>> + const unsigned hact = 720;
>>>> + const unsigned hdelay = 15;
>>>> + unsigned vact;
>>>> + unsigned vdelay;
>>>> + int ret;
>>>>
>>>> if (!(norm & (V4L2_STD_NTSC | V4L2_STD_PAL)))
>>>> return -EINVAL;
>>>>
>>>> priv->norm = norm;
>>>> + if (norm & V4L2_STD_525_60) {
>>>> + vact = 240;
>>>> + vdelay = 18;
>>>> + ret = tw9910_mask_set(client, VVBI, 0x10, 0x10);
>>>> + } else {
>>>> + vact = 288;
>>>> + vdelay = 24;
>>>> + ret = tw9910_mask_set(client, VVBI, 0x10, 0x00);
>>>> + }
>>>> + if (!ret)
>>>> + ret = i2c_smbus_write_byte_data(client, CROP_HI,
>>>> + ((vdelay >> 2) & 0xc0) |
>>>> + ((vact >> 4) & 0x30) |
>>>> + ((hdelay >> 6) & 0x0c) |
>>>> + ((hact >> 8) & 0x03));
>>>
>>> I personally would find ((x & 0xc0) >> {2,4,6,8}) a bit easier for the
>>> eyes, but this works as well for me:)
>>>
>>>> + if (!ret)
>>>> + ret = i2c_smbus_write_byte_data(client, VDELAY_LO,
>>>> + vdelay & 0xff);
>>>> + if (!ret)
>>>> + ret = i2c_smbus_write_byte_data(client, VACTIVE_LO,
>>>> + vact & 0xff);
>>>>
>>>> - return 0;
>>>> + return ret;
>>>> }
>>>>
>>>> #ifdef CONFIG_VIDEO_ADV_DEBUG
>>>> @@ -820,6 +846,7 @@ static int tw9910_video_probe(struct i2c_client *client)
>>>> "tw9910 Product ID %0x:%0x\n", id, priv->revision);
>>>>
>>>> priv->norm = V4L2_STD_NTSC;
>>>> + priv->scale = &tw9910_ntsc_scales[0];
>>>
>>> Why do you need this? So far everywhere in the code priv->scale is either
>>> checked or set before use. Don't see why an additional initialisation is
>>> needed.
>>
>> If you just start streaming without explicitly setting up formats (which is
>> allowed), then priv->scale is still NULL.
>
> Yes, it can well be NULL, but it is also unused. Before it is used it will
> be set, while it is unused it is allowed to stay NULL.
No. If you start streaming without the set_fmt op having been called, then
s_stream will return an error since priv->scale is NULL. This is wrong. Since
this driver defaults to NTSC the initial setup should be for NTSC and it should
be ready for streaming.
So priv->scale *is* used: in s_stream. And it is not necessarily set before use.
E.g. if you load the driver and run 'v4l2-ctl --stream-out-mmap' you will hit this
case. It's how I found this bug.
It's a trivial one liner to ensure a valid priv->scale pointer.
Regards,
Hans
>
> Thanks
> Guennadi
>
>> V4L2 always assumes that there is some initial format configured, and this line
>> enables that for this driver (NTSC).
>>
>> Regards,
>>
>> Hans
>>
>>>
>>> Thanks
>>> Guennadi
>>>
>>>>
>>>> done:
>>>> tw9910_s_power(&priv->subdev, 0);
>>>> --
>>>> 2.1.4
>>>>
>>> --
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>>
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