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Message-ID: <9d1cb43e-ee9e-b68a-c700-e3ed70f16287@gmail.com>
Date: Wed, 17 Apr 2019 10:56:55 -0700
From: Steve Longerbeam <slongerbeam@...il.com>
To: Niklas Söderlund <niklas.soderlund@...natech.se>
Cc: linux-media@...r.kernel.org, Eugeniu Rosca <erosca@...adit-jv.com>,
Michael Rodin <mrodin@...adit-jv.com>,
Eugen Friedrich <efriedrich@...adit-jv.com>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
"open list:MEDIA DRIVERS FOR RENESAS - VIN"
<linux-renesas-soc@...r.kernel.org>,
open list <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] media: rcar-csi2: Fix field detection
Hi Nklas,
On 4/16/19 4:59 PM, Steve Longerbeam wrote:
> Hi Niklas,
>
> On 4/16/19 4:50 PM, Niklas Söderlund wrote:
>> Hi Steve,
>>
>> Thanks for your work.
>>
>> I upported most rcar-csi2 patches but a few of them are still pending,
>> an alternating version based on this BSP patch is already on its way.
>>
>> https://patchwork.linuxtv.org/patch/55623/
>
> Great, that patch confirms that FLD_NUM should be set to 0 or 1 when
> setting FLD_DET_SEL = 0x01.
>
> But your patch has it inverted. NTSC should be FLD_NUM=1, PAL should
> be FLD_NUM=0. Can you please confirm that after reading the commit
> description of my RFC patch.
Can you please confirm that your patch at
https://patchwork.linuxtv.org/patch/55623 has the FLD_NUM bits inverted?
It's the most important question regarding this. Please review my
reasoning in the RFC patch. NTSC should be FLD_NUM=1, PAL should be
FLD_NUM=0.
Also, slightly off-topic, but another question:
Do you know if it is possible to capture from a source that is sending
SEQ-BT/TB and transfer to userspace as unmodified SEQ-BT/TB without
requiring the capture of each field individually and concatenating them?
In other words, treat the frame from the source the same as progressive,
i.e. as if the source were sending V4L2_FIELD_NONE. That is, program
VnMC.IM bits as VNMC_IM_ODD_EVEN and use continuous frame capture mode.
TIA,
Steve
>
>
>
>>
>> On 2019-04-16 16:38:07 -0700, Steve Longerbeam wrote:
>>> The RCAR Gen3 hardware manual doesn't mention that the "Word Count"
>>> field
>>> in the MIPI CSI-2 Frame Start packet is really the frame number. FS
>>> packets
>>> are short packets, and short packets do not have a WC but rather a
>>> 16-bit
>>> data field, and for Frame synchronization packets (FS/FE) the 16-bit
>>> data
>>> field contains a frame number.
>>>
>>> Here is a reprinting from the MIPI CSI-2 specification, version 2
>>> (section 9.1.2 Low Level Protocol Short Packet Format):
>>>
>>> "Figure 42 and Figure 43 show the Low Level Protocol Short Packet
>>> structures for the D-PHY and C-PHY physical layer options,
>>> respectively.
>>> For each option, the Short Packet structure matches the Packet
>>> Header of
>>> the corresponding Low Level Protocol Long Packet structure with the
>>> exception that the Packet Header Word Count (WC) field shall be
>>> replaced
>>> by the Short Packet Data Field...For Frame Synchronization Data Types
>>> the Short Packet Data Field shall be the frame number..."
>>>
>>> Also in section 9.8.1 Frame Synchronization Packets, the CSI-2 spec
>>> reads:
>>>
>>> "The behavior of the 16-bit frame number shall be as one of the
>>> following
>>> - Frame number is always zero – frame number is inoperative.
>>> - Frame number increments by 1 for every FS packet with the same
>>> Virtual
>>> Channel and is periodically reset to one e.g. 1, 2, 1, 2, 1, 2,
>>> 1, 2 or
>>> 1, 2, 3, 4, 1, 2, 3, 4"
>>>
>>> So from the above, FLD_NUM in the FLD register matches against the
>>> frame number transmitted by the CSI-2 source in the Frame Start Packet,
>>> and goes as "1,2,1,2,1,2" or "1,2,3,4,...,1,2,3,4". If there is a
>>> match,
>>> the RCAR CSI-2 receiver declares the field as the even, e.g. the
>>> BOTTOM,
>>> field.
>>>
>>> NTSC transmits bottom/even field first, and PAL and HD transmit top/odd
>>> field first. So fields with a frame number 1 in the CSI-2 Frame Start
>>> Packet are bottom/even fields for NTSC, and frame number 2 are
>>> bottom/even
>>> fields for PAL/HD.
>>>
>>> But the above assumes the transmitting CSI-2 sensor is sending frame
>>> numbers in the sequence "1,2,1,2,...". But according to the CSI-2 spec,
>>> sensors are also allowed to send frame numbers that simply increment as
>>> in "1,2,3,4,...". To generalize to catch those cases, set FLD_DET_SEL
>>> to 0x01, which according to the RCAR Gen3 hardware manual means "the
>>> field is detected as the EVEN field when FLD_NUM[0] matches WC[0]".
>>> Then, the even/bottom fields have odd frame numbers for NTSC, and even
>>> frame numbers for PAL (this patch assumes HDMI sources will not
>>> implement .g_std(), so std will be 0 in that case).
>>>
>>> Finally, set the FLD register to non-zero value only if trnsmitter is
>>> sending ALTERNATE fields.
>>>
>>> Signed-off-by: Steve Longerbeam <slongerbeam@...il.com>
>>> ---
>>> drivers/media/platform/rcar-vin/rcar-csi2.c | 37
>>> ++++++++++++++++++---
>>> 1 file changed, 32 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/media/platform/rcar-vin/rcar-csi2.c
>>> b/drivers/media/platform/rcar-vin/rcar-csi2.c
>>> index a438ec2c218f..c5bee20d7907 100644
>>> --- a/drivers/media/platform/rcar-vin/rcar-csi2.c
>>> +++ b/drivers/media/platform/rcar-vin/rcar-csi2.c
>>> @@ -67,6 +67,7 @@ struct rcar_csi2;
>>> /* Field Detection Control */
>>> #define FLD_REG 0x1c
>>> #define FLD_FLD_NUM(n) (((n) & 0xff) << 16)
>>> +#define FLD_FLD_DET_SEL(n) (((n) & 0x3) << 4)
>>> #define FLD_FLD_EN4 BIT(3)
>>> #define FLD_FLD_EN3 BIT(2)
>>> #define FLD_FLD_EN2 BIT(1)
>>> @@ -462,10 +463,11 @@ static int rcsi2_calc_mbps(struct rcar_csi2
>>> *priv, unsigned int bpp)
>>> return mbps;
>>> }
>>> -static int rcsi2_start(struct rcar_csi2 *priv)
>>> +static int rcsi2_start(struct rcar_csi2 *priv, struct v4l2_subdev
>>> *nextsd)
>>> {
>>> const struct rcar_csi2_format *format;
>>> - u32 phycnt, vcdt = 0, vcdt2 = 0;
>>> + u32 phycnt, vcdt = 0, vcdt2 = 0, fld = 0;
>>> + v4l2_std_id std = 0;
>>> unsigned int i;
>>> int mbps, ret;
>>> @@ -476,6 +478,10 @@ static int rcsi2_start(struct rcar_csi2 *priv)
>>> /* Code is validated in set_fmt. */
>>> format = rcsi2_code_to_fmt(priv->mf.code);
>>> + ret = v4l2_subdev_call(nextsd, video, g_std, &std);
>>> + if (ret < 0 && ret != -ENOIOCTLCMD && ret != -ENODEV)
>>> + return ret;
>>> +
>>> /*
>>> * Enable all supported CSI-2 channels with virtual channel and
>>> * data type matching.
>>> @@ -509,9 +515,30 @@ static int rcsi2_start(struct rcar_csi2 *priv)
>>> rcsi2_reset(priv);
>>> rcsi2_write(priv, PHTC_REG, 0);
>>> + /*
>>> + * NTSC standard transmits even/bottom field first, then odd/top.
>>> + * PAL standard and interlaced HD transmit odd/top field first,
>>> + * then even/bottom.
>>> + *
>>> + * For CSI-2 sensors that transmit frame numbers (in the CSI-2
>>> + * Frame Start packet) as "1,2,1,2,..." or "1,2,3,4,5,...", then:
>>> + *
>>> + * - for NTSC, the even/bottom fields have odd frame numbers.
>>> + * - for PAL and HD, the even/bottom fields have even frame
>>> numbers.
>>> + */
>>> + if (priv->mf.field == V4L2_FIELD_ALTERNATE) {
>>> + fld = FLD_FLD_DET_SEL(1) | FLD_FLD_EN4 | FLD_FLD_EN3 |
>>> + FLD_FLD_EN2 | FLD_FLD_EN;
>>> +
>>> + if (std & V4L2_STD_525_60)
>>> + fld |= FLD_FLD_NUM(1); /* NTSC */
>>> + else
>>> + fld |= FLD_FLD_NUM(0); /* PAL or HD */
>>> + }
>>> +
>>> /* Configure */
>>> - rcsi2_write(priv, FLD_REG, FLD_FLD_NUM(2) | FLD_FLD_EN4 |
>>> - FLD_FLD_EN3 | FLD_FLD_EN2 | FLD_FLD_EN);
>>> + rcsi2_write(priv, FLD_REG, fld);
>>> +
>>> rcsi2_write(priv, VCDT_REG, vcdt);
>>> if (vcdt2)
>>> rcsi2_write(priv, VCDT2_REG, vcdt2);
>>> @@ -591,7 +618,7 @@ static int rcsi2_s_stream(struct v4l2_subdev
>>> *sd, int enable)
>>> if (enable && priv->stream_count == 0) {
>>> pm_runtime_get_sync(priv->dev);
>>> - ret = rcsi2_start(priv);
>>> + ret = rcsi2_start(priv, nextsd);
>>> if (ret) {
>>> pm_runtime_put(priv->dev);
>>> goto out;
>>> --
>>> 2.17.1
>>>
>
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