Re: [Intel-gfx] [PATCH v10 18/19] drm/vc4: vec: Add support for more analog TV standards

2022-11-21 Thread Mateusz Kwiatkowski 
Hi Mauro,

As the author of the original version of this commit, and also a person who
argued quite a bit on these descriptions and decisions, let me chip in a bit.

W dniu 17.11.2022 o 16:49, Mauro Carvalho Chehab pisze:
> On Thu, 17 Nov 2022 10:29:01 +0100
> Maxime Ripard  wrote:
>
>> From: Mateusz Kwiatkowski 
>>
>> Add support for the following composite output modes (all of them are
>> somewhat more obscure than the previously defined ones):
>>
>> - NTSC_443 - NTSC-style signal with the chroma subcarrier shifted to
>>   4.43361875 MHz (the PAL subcarrier frequency). Never used for
>>   broadcasting, but sometimes used as a hack to play NTSC content in PAL
>>   regions (e.g. on VCRs).
>
>> - PAL_N - PAL with alternative chroma subcarrier frequency,
>>   3.58205625 MHz. Used as a broadcast standard in Argentina, Paraguay
>>   and Uruguay to fit 576i50 with colour in 6 MHz channel raster.
>
> That's not right. Argentina uses a different standard than Paraguay and
> Uruguai.
>
> See, there are two variants of PAL/N. The original one and PAL/N' - also
> called PAL/NC or PAL/CN (Combination N). Some of the timings are 
> different on /NC variant.
>
> As far as I'm aware, PAL/Nc is used in Argentina, while
> PAL/N is used in Paraguai and Uruguai, but I may be wrong on that,
> as it has been a long time since had to touch on this.

If you say so - maybe that's true. But I tried to find any differences between
PAL-N and PAL-Nc many times and haven't found anything concrete. The only
authoritative source where System N and "Combination N/PAL" seem to be mentioned
as separate entities is BT.1701
. However:

a) the differences are very subtle (with "combination N/PAL" being just a tad
   stricter than what's mentioned for System N)
b) "Combination N/PAL" can be understood as just "System N combined with PAL
   color", as opposed to "raw", black&white System N. This intepretation is also
   what the user calling themselves "Alcahemist" suggests here:
   https://en.wikipedia.org/wiki/Talk:PAL#PAL-N_versus_PAL-Nc

This is of course far from an authoritative source. If you have a definitive
source for PAL-N and PAL-Nc being different, or concrete information on what is
different between them specifically, then so be it. But I tried and haven't
found anything conclusive.

>> - PAL60 - 480i60 signal with PAL-style color at normal European PAL
>>   frequency. Another non-standard, non-broadcast mode, used in similar
>>   contexts as NTSC_443. Some displays support one but not the other.
>
>> - SECAM - French frequency-modulated analog color standard; also have
>>   been broadcast in Eastern Europe and various parts of Africa and Asia.
>>   Uses the same 576i50 timings as PAL.
>
> This is also wrong. just like PAL, there are several variants of SECAM,
> one used in France, and a different one in France overseas and on
> previous France colonies in Africa and Asia. Eastern Europe also used
> different variants of SECAM.

This is true. However, those differed only in RF modulation. For example,
French SECAM-L used positive video modulation and AM sound, while Eastern
European SECAM-D/K used negative video modulation and FM sound. But the
baseband composite signals were identical.

There were several other variants of SECAM, like early SECAM/V vs. SECAM/H
("Field identification" vs. "Line identification") which moved the color
identification signals from VBI to HBI. But that's a change that all SECAM
regions, including both France and Eastern Europe did in the 1980s to
acommodate for teletext. Again, authoritative sources are scarce, but see e.g.
https://web.archive.org/web/20160303232903/http://www.pembers.freeserve.co.uk/World-TV-Standards/Colour-Standards.html
(search for "Synchronisation of SECAM colour transmissions" on the page).

There's also MESECAM, but that only applies to encoding on VHS and Betamax
tapes, not the signals themselves. There was also SECAM-M for 525-line (480i)
signals, but I haven't found any conclusive evidence that it was ever used for
broadcast anywhere

So yeah, SECAM can be a bit confusing, but AFAIK there's only one standard if
we're talking about the composite video layer.

--

Some *really* old (like, 1960s old) versions of CCIR documents also listed more
substantial differences between various 625-line systems, including the number
of active lines varying from 571 to 589. But all revisions from 1974 onward list
the modern value of 575 active lines for all the variants, making them differ
only in RF modulation details. Which is beyond the scope of what the "TV mode"
property is supposed to do.

>> Also added some comments explaining color subcarrier frequency
>> registers.
>>
>> Acked-by: Noralf Trønnes 
>> Signed-off-by: Mateusz Kwiatkowski 
>> Tested-by: Mateusz Kwiatkowski 
>> Signed-off-by: Maxime Ripard 
>>
>> ---
>> Changes in v6:
>> - Support PAL60 again
>> ---
>>  drivers/gpu/drm/vc4/vc4_vec.c | 111 
>> ++

Re: [Intel-gfx] [PATCH v10 18/19] drm/vc4: vec: Add support for more analog TV standards

2022-11-17 Thread Maxime Ripard 
On Thu, Nov 17, 2022 at 04:49:28PM +0100, Mauro Carvalho Chehab wrote:
> On Thu, 17 Nov 2022 10:29:01 +0100
> Maxime Ripard  wrote:
> 
> > From: Mateusz Kwiatkowski 
> > 
> > Add support for the following composite output modes (all of them are
> > somewhat more obscure than the previously defined ones):
> > 
> > - NTSC_443 - NTSC-style signal with the chroma subcarrier shifted to
> >   4.43361875 MHz (the PAL subcarrier frequency). Never used for
> >   broadcasting, but sometimes used as a hack to play NTSC content in PAL
> >   regions (e.g. on VCRs).
> 
> > - PAL_N - PAL with alternative chroma subcarrier frequency,
> >   3.58205625 MHz. Used as a broadcast standard in Argentina, Paraguay
> >   and Uruguay to fit 576i50 with colour in 6 MHz channel raster.
> 
> That's not right. Argentina uses a different standard than Paraguay and
> Uruguai.
> 
> See, there are two variants of PAL/N. The original one and PAL/N' - also
> called PAL/NC or PAL/CN (Combination N). Some of the timings are 
> different on /NC variant.
> 
> As far as I'm aware, PAL/Nc is used in Argentina, while
> PAL/N is used in Paraguai and Uruguai, but I may be wrong on that,
> as it has been a long time since had to touch on this.
> 
> > - PAL60 - 480i60 signal with PAL-style color at normal European PAL
> >   frequency. Another non-standard, non-broadcast mode, used in similar
> >   contexts as NTSC_443. Some displays support one but not the other.
> 
> > - SECAM - French frequency-modulated analog color standard; also have
> >   been broadcast in Eastern Europe and various parts of Africa and Asia.
> >   Uses the same 576i50 timings as PAL.
> 
> This is also wrong. just like PAL, there are several variants of SECAM,
> one used in France, and a different one in France overseas and on
> previous France colonies in Africa and Asia. Eastern Europe also used
> different variants of SECAM.

And that's fine? Everything I did is supposed to be easy to extend if
and when needed, so if someone has some interest in providing support
for more standards, they are very welcome to do so.

I won't do it in this series though.

Maxime


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Re: [Intel-gfx] [PATCH v10 18/19] drm/vc4: vec: Add support for more analog TV standards

2022-11-17 Thread Mauro Carvalho Chehab 
On Thu, 17 Nov 2022 10:29:01 +0100
Maxime Ripard  wrote:

> From: Mateusz Kwiatkowski 
> 
> Add support for the following composite output modes (all of them are
> somewhat more obscure than the previously defined ones):
> 
> - NTSC_443 - NTSC-style signal with the chroma subcarrier shifted to
>   4.43361875 MHz (the PAL subcarrier frequency). Never used for
>   broadcasting, but sometimes used as a hack to play NTSC content in PAL
>   regions (e.g. on VCRs).

> - PAL_N - PAL with alternative chroma subcarrier frequency,
>   3.58205625 MHz. Used as a broadcast standard in Argentina, Paraguay
>   and Uruguay to fit 576i50 with colour in 6 MHz channel raster.

That's not right. Argentina uses a different standard than Paraguay and
Uruguai.

See, there are two variants of PAL/N. The original one and PAL/N' - also
called PAL/NC or PAL/CN (Combination N). Some of the timings are 
different on /NC variant.

As far as I'm aware, PAL/Nc is used in Argentina, while
PAL/N is used in Paraguai and Uruguai, but I may be wrong on that,
as it has been a long time since had to touch on this.

> - PAL60 - 480i60 signal with PAL-style color at normal European PAL
>   frequency. Another non-standard, non-broadcast mode, used in similar
>   contexts as NTSC_443. Some displays support one but not the other.

> - SECAM - French frequency-modulated analog color standard; also have
>   been broadcast in Eastern Europe and various parts of Africa and Asia.
>   Uses the same 576i50 timings as PAL.

This is also wrong. just like PAL, there are several variants of SECAM,
one used in France, and a different one in France overseas and on
previous France colonies in Africa and Asia. Eastern Europe also used
different variants of SECAM.

> 
> Also added some comments explaining color subcarrier frequency
> registers.
> 
> Acked-by: Noralf Trønnes 
> Signed-off-by: Mateusz Kwiatkowski 
> Tested-by: Mateusz Kwiatkowski 
> Signed-off-by: Maxime Ripard 
> 
> ---
> Changes in v6:
> - Support PAL60 again
> ---
>  drivers/gpu/drm/vc4/vc4_vec.c | 111 
> --
>  1 file changed, 107 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vc4/vc4_vec.c b/drivers/gpu/drm/vc4/vc4_vec.c
> index a828fc6fb776..d23dbad3cbf6 100644
> --- a/drivers/gpu/drm/vc4/vc4_vec.c
> +++ b/drivers/gpu/drm/vc4/vc4_vec.c
> @@ -46,6 +46,7 @@
>  #define VEC_CONFIG0_YDEL(x)  ((x) << 26)
>  #define VEC_CONFIG0_CDEL_MASKGENMASK(25, 24)
>  #define VEC_CONFIG0_CDEL(x)  ((x) << 24)
> +#define VEC_CONFIG0_SECAM_STDBIT(21)
>  #define VEC_CONFIG0_PBPR_FIL BIT(18)
>  #define VEC_CONFIG0_CHROMA_GAIN_MASK GENMASK(17, 16)
>  #define VEC_CONFIG0_CHROMA_GAIN_UNITY(0 << 16)
> @@ -76,6 +77,27 @@
>  #define VEC_SOFT_RESET   0x10c
>  #define VEC_CLMP0_START  0x144
>  #define VEC_CLMP0_END0x148
> +
> +/*
> + * These set the color subcarrier frequency
> + * if VEC_CONFIG1_CUSTOM_FREQ is enabled.
> + *
> + * VEC_FREQ1_0 contains the most significant 16-bit half-word,
> + * VEC_FREQ3_2 contains the least significant 16-bit half-word.
> + * 0x8000 seems to be equivalent to the pixel clock
> + * (which itself is the VEC clock divided by 8).
> + *
> + * Reference values (with the default pixel clock of 13.5 MHz):
> + *
> + * NTSC  (3579545.[45] Hz) - 0x21F07C1F
> + * PAL   (4433618.75 Hz)   - 0x2A098ACB
> + * PAL-M (3575611.[888111] Hz) - 0x21E6EFE3
> + * PAL-N (3582056.25 Hz)   - 0x21F69446
> + *
> + * NOTE: For SECAM, it is used as the Dr center frequency,
> + * regardless of whether VEC_CONFIG1_CUSTOM_FREQ is enabled or not;
> + * that is specified as 4406250 Hz, which corresponds to 0x29C71C72.
> + */
>  #define VEC_FREQ3_2  0x180
>  #define VEC_FREQ1_0  0x184
>  
> @@ -118,6 +140,14 @@
>  
>  #define VEC_INTERRUPT_CONTROL0x190
>  #define VEC_INTERRUPT_STATUS 0x194
> +
> +/*
> + * Db center frequency for SECAM; the clock for this is the same as for
> + * VEC_FREQ3_2/VEC_FREQ1_0, which is used for Dr center frequency.
> + *
> + * This is specified as 425 Hz, which corresponds to 0x284BDA13.
> + * That is also the default value, so no need to set it explicitly.
> + */
>  #define VEC_FCW_SECAM_B  0x198
>  #define VEC_SECAM_GAIN_VAL   0x19c
>  
> @@ -197,10 +227,15 @@ enum vc4_vec_tv_mode_id {
>   VC4_VEC_TV_MODE_NTSC_J,
>   VC4_VEC_TV_MODE_PAL,
>   VC4_VEC_TV_MODE_PAL_M,
> + VC4_VEC_TV_MODE_NTSC_443,
> + VC4_VEC_TV_MODE_PAL_60,
> + VC4_VEC_TV_MODE_PAL_N,
> + VC4_VEC_TV_MODE_SECAM,
>  };
>  
>  struct vc4_vec_tv_mode {
>   unsigned int mode;
> + u16 expected_htotal;
>   u32 config0;
>   u32 config1;
>   u32 custom_freq;
> @@ -236,35 +271,68 @@ static const struct debugfs_reg32 vec_regs[] = {
>  static const struct vc4_vec_tv_mode vc4_vec_tv_modes[] = {
>   {
>

[Intel-gfx] [PATCH v10 18/19] drm/vc4: vec: Add support for more analog TV standards

2022-11-17 Thread Maxime Ripard 
From: Mateusz Kwiatkowski 

Add support for the following composite output modes (all of them are
somewhat more obscure than the previously defined ones):

- NTSC_443 - NTSC-style signal with the chroma subcarrier shifted to
  4.43361875 MHz (the PAL subcarrier frequency). Never used for
  broadcasting, but sometimes used as a hack to play NTSC content in PAL
  regions (e.g. on VCRs).
- PAL_N - PAL with alternative chroma subcarrier frequency,
  3.58205625 MHz. Used as a broadcast standard in Argentina, Paraguay
  and Uruguay to fit 576i50 with colour in 6 MHz channel raster.
- PAL60 - 480i60 signal with PAL-style color at normal European PAL
  frequency. Another non-standard, non-broadcast mode, used in similar
  contexts as NTSC_443. Some displays support one but not the other.
- SECAM - French frequency-modulated analog color standard; also have
  been broadcast in Eastern Europe and various parts of Africa and Asia.
  Uses the same 576i50 timings as PAL.

Also added some comments explaining color subcarrier frequency
registers.

Acked-by: Noralf Trønnes 
Signed-off-by: Mateusz Kwiatkowski 
Tested-by: Mateusz Kwiatkowski 
Signed-off-by: Maxime Ripard 

---
Changes in v6:
- Support PAL60 again
---
 drivers/gpu/drm/vc4/vc4_vec.c | 111 --
 1 file changed, 107 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_vec.c b/drivers/gpu/drm/vc4/vc4_vec.c
index a828fc6fb776..d23dbad3cbf6 100644
--- a/drivers/gpu/drm/vc4/vc4_vec.c
+++ b/drivers/gpu/drm/vc4/vc4_vec.c
@@ -46,6 +46,7 @@
 #define VEC_CONFIG0_YDEL(x)((x) << 26)
 #define VEC_CONFIG0_CDEL_MASK  GENMASK(25, 24)
 #define VEC_CONFIG0_CDEL(x)((x) << 24)
+#define VEC_CONFIG0_SECAM_STD  BIT(21)
 #define VEC_CONFIG0_PBPR_FIL   BIT(18)
 #define VEC_CONFIG0_CHROMA_GAIN_MASK   GENMASK(17, 16)
 #define VEC_CONFIG0_CHROMA_GAIN_UNITY  (0 << 16)
@@ -76,6 +77,27 @@
 #define VEC_SOFT_RESET 0x10c
 #define VEC_CLMP0_START0x144
 #define VEC_CLMP0_END  0x148
+
+/*
+ * These set the color subcarrier frequency
+ * if VEC_CONFIG1_CUSTOM_FREQ is enabled.
+ *
+ * VEC_FREQ1_0 contains the most significant 16-bit half-word,
+ * VEC_FREQ3_2 contains the least significant 16-bit half-word.
+ * 0x8000 seems to be equivalent to the pixel clock
+ * (which itself is the VEC clock divided by 8).
+ *
+ * Reference values (with the default pixel clock of 13.5 MHz):
+ *
+ * NTSC  (3579545.[45] Hz) - 0x21F07C1F
+ * PAL   (4433618.75 Hz)   - 0x2A098ACB
+ * PAL-M (3575611.[888111] Hz) - 0x21E6EFE3
+ * PAL-N (3582056.25 Hz)   - 0x21F69446
+ *
+ * NOTE: For SECAM, it is used as the Dr center frequency,
+ * regardless of whether VEC_CONFIG1_CUSTOM_FREQ is enabled or not;
+ * that is specified as 4406250 Hz, which corresponds to 0x29C71C72.
+ */
 #define VEC_FREQ3_20x180
 #define VEC_FREQ1_00x184
 
@@ -118,6 +140,14 @@
 
 #define VEC_INTERRUPT_CONTROL  0x190
 #define VEC_INTERRUPT_STATUS   0x194
+
+/*
+ * Db center frequency for SECAM; the clock for this is the same as for
+ * VEC_FREQ3_2/VEC_FREQ1_0, which is used for Dr center frequency.
+ *
+ * This is specified as 425 Hz, which corresponds to 0x284BDA13.
+ * That is also the default value, so no need to set it explicitly.
+ */
 #define VEC_FCW_SECAM_B0x198
 #define VEC_SECAM_GAIN_VAL 0x19c
 
@@ -197,10 +227,15 @@ enum vc4_vec_tv_mode_id {
VC4_VEC_TV_MODE_NTSC_J,
VC4_VEC_TV_MODE_PAL,
VC4_VEC_TV_MODE_PAL_M,
+   VC4_VEC_TV_MODE_NTSC_443,
+   VC4_VEC_TV_MODE_PAL_60,
+   VC4_VEC_TV_MODE_PAL_N,
+   VC4_VEC_TV_MODE_SECAM,
 };
 
 struct vc4_vec_tv_mode {
unsigned int mode;
+   u16 expected_htotal;
u32 config0;
u32 config1;
u32 custom_freq;
@@ -236,35 +271,68 @@ static const struct debugfs_reg32 vec_regs[] = {
 static const struct vc4_vec_tv_mode vc4_vec_tv_modes[] = {
{
.mode = DRM_MODE_TV_MODE_NTSC,
+   .expected_htotal = 858,
.config0 = VEC_CONFIG0_NTSC_STD | VEC_CONFIG0_PDEN,
.config1 = VEC_CONFIG1_C_CVBS_CVBS,
},
+   {
+   .mode = DRM_MODE_TV_MODE_NTSC_443,
+   .expected_htotal = 858,
+   .config0 = VEC_CONFIG0_NTSC_STD,
+   .config1 = VEC_CONFIG1_C_CVBS_CVBS | VEC_CONFIG1_CUSTOM_FREQ,
+   .custom_freq = 0x2a098acb,
+   },
{
.mode = DRM_MODE_TV_MODE_NTSC_J,
+   .expected_htotal = 858,
.config0 = VEC_CONFIG0_NTSC_STD,
.config1 = VEC_CONFIG1_C_CVBS_CVBS,
},
{
.mode = DRM_MODE_TV_MODE_PAL,
+   .expected_htotal = 864,
.config0 = VEC_CONFIG0_PAL_BDGHI_STD,
.config1 = VEC_CONFIG1_C_CVBS_CVBS,
},
+   {
+   /