Message-ID:
 <PH0PR11MB561131B7C16E3D2699A6EF9981CA2@PH0PR11MB5611.namprd11.prod.outlook.com>
Date: Thu, 6 Mar 2025 05:15:13 +0000
From: <Shravan.Chippa@...rochip.com>
To: <dave.stevenson@...pberrypi.com>, <kieran.bingham@...asonboard.com>
CC: <sakari.ailus@...ux.intel.com>, <mchehab@...nel.org>,
	<linux-media@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<Conor.Dooley@...rochip.com>, <Valentina.FernandezAlanis@...rochip.com>,
	<Praveen.Kumar@...rochip.com>
Subject: RE: [PATCH V7 4/4] media: i2c: imx334: add modes for 720p and 480p
 resolutions



> -----Original Message-----
> From: Dave Stevenson <dave.stevenson@...pberrypi.com>
> Sent: Wednesday, March 5, 2025 6:30 PM
> To: Kieran Bingham <kieran.bingham@...asonboard.com>
> Cc: Sakari Ailus <sakari.ailus@...ux.intel.com>; shravan Chippa - I35088
> <Shravan.Chippa@...rochip.com>; mchehab@...nel.org; linux-
> media@...r.kernel.org; linux-kernel@...r.kernel.org; Conor Dooley -
> M52691 <Conor.Dooley@...rochip.com>; Valentina Fernandez Alanis -
> M63239 <Valentina.FernandezAlanis@...rochip.com>; Praveen Kumar -
> I30718 <Praveen.Kumar@...rochip.com>
> Subject: Re: [PATCH V7 4/4] media: i2c: imx334: add modes for 720p and 480p
> resolutions
> 
> [You don't often get email from dave.stevenson@...pberrypi.com. Learn why
> this is important at https://aka.ms/LearnAboutSenderIdentification ]
> 
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the
> content is safe
> 
> Hi Kieran, Sakari, Shravan, and Tarang
> 
> On Wed, 5 Mar 2025 at 12:17, Kieran Bingham
> <kieran.bingham@...asonboard.com> wrote:
> >
> > Quoting Sakari Ailus (2025-03-05 11:50:53)
> > > Hi Kieran, Shravan,
> > >
> > > On Wed, Mar 05, 2025 at 10:45:42AM +0000, Kieran Bingham wrote:
> > > > Quoting Shravan.Chippa@...rochip.com (2025-03-05 10:22:12)
> > > > > Hi Kieran
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: Kieran Bingham <kieran.bingham@...asonboard.com>
> > > > > > Sent: Wednesday, March 5, 2025 3:05 PM
> > > > > > To: mchehab@...nel.org; sakari.ailus@...ux.intel.com; shravan
> > > > > > Chippa -
> > > > > > I35088 <Shravan.Chippa@...rochip.com>
> > > > > > Cc: linux-media@...r.kernel.org; linux-kernel@...r.kernel.org;
> > > > > > Conor Dooley
> > > > > > - M52691 <Conor.Dooley@...rochip.com>; Valentina Fernandez
> > > > > > Alanis -
> > > > > > M63239 <Valentina.FernandezAlanis@...rochip.com>; Praveen
> > > > > > Kumar -
> > > > > > I30718 <Praveen.Kumar@...rochip.com>; shravan Chippa - I35088
> > > > > > <Shravan.Chippa@...rochip.com>
> > > > > > Subject: Re: [PATCH V7 4/4] media: i2c: imx334: add modes for
> > > > > > 720p and 480p resolutions
> > > > > >
> > > > > > EXTERNAL EMAIL: Do not click links or open attachments unless
> > > > > > you know the content is safe
> > > > > >
> > > > > > Quoting shravan kumar (2025-03-05 05:14:42)
> > > > > > > From: Shravan Chippa <shravan.chippa@...rochip.com>
> > > > > > >
> > > > > > > Added support for 1280x720@30 and 640x480@30 resolutions
> 
> Silly question - why is the frame rate specified here? Is that the minimum,
> maximum, or default framerate, as we have V4L2_CID_VBLANK for varying
> the frame rate.

Yes, default is 30fps, max upto 60fps

Thanks,
Shravan

> 
> > > > > > >
> > > > > > > Signed-off-by: Shravan Chippa <shravan.chippa@...rochip.com>
> > > > > > > ---
> > > > > > >  drivers/media/i2c/imx334.c | 66
> > > > > > > ++++++++++++++++++++++++++++++++++++++
> > > > > > >  1 file changed, 66 insertions(+)
> > > > > > >
> > > > > > > diff --git a/drivers/media/i2c/imx334.c
> > > > > > > b/drivers/media/i2c/imx334.c index
> > > > > > > a7c0bd38c9b8..8cd1eecd0143 100644
> > > > > > > --- a/drivers/media/i2c/imx334.c
> > > > > > > +++ b/drivers/media/i2c/imx334.c
> > > > > > > @@ -314,6 +314,46 @@ static const struct imx334_reg
> > > > > > common_mode_regs[] = {
> > > > > > >         {0x3002, 0x00},
> > > > > > >  };
> > > > > > >
> > > > > > > +/* Sensor mode registers for 640x480@...ps */ static const
> > > > > > > +struct imx334_reg mode_640x480_regs[] = {
> > > > > > > +       {0x302c, 0x70},
> > > > > > > +       {0x302d, 0x06},
> > > > > >
> > > > > > These two are a single 16 bit register HTRIMMING_START = 1648
> > > > > >
> > > > > > > +       {0x302e, 0x80},
> > > > > > > +       {0x302f, 0x02},
> > > > > >
> > > > > > These two are a single 16 bit register HNUM = 640
> > > > > >
> > > > > > > +       {0x3074, 0x48},
> > > > > > > +       {0x3075, 0x07},
> > > > > >
> > > > > > These two are a single 16 bit (well, 12 bit value)
> > > > > > AREA3_ST_ADR_1 = 1864
> > > > > >
> > > > > > > +       {0x308e, 0x49},
> > > > > > > +       {0x308f, 0x07},
> > > > > >
> > > > > > These two are a single 16 bit register AREA3_ST_ADR_2 = 1865
> > > > > >
> > > > > > > +       {0x3076, 0xe0},
> > > > > > > +       {0x3077, 0x01},
> > > > > >
> > > > > > These two are a single 16 bit register AREA3_WIDTH_1 = 480
> > > > > >
> > > > > > > +       {0x3090, 0xe0},
> > > > > > > +       {0x3091, 0x01},
> > > > > >
> > > > > > These two are a single 16 bit register AREA3_WIDTH_2 = 480
> > > > > >
> > > > > > > +       {0x3308, 0xe0},
> > > > > > > +       {0x3309, 0x01},
> > > > > >
> > > > > > These two are a single 16 bit register Y_OUT_SIZE
> > > > > >
> > > > > > Don't you think
> > > > > >         { Y_OUT_SIZE, 480 },
> > > > > >
> > > > > > Is so much more readable and easier to comprehend and maintain?
> > > > > >
> > > > > >
> > > > > > > +       {0x30d8, 0x30},
> > > > > > > +       {0x30d9, 0x0b},
> > > > > >
> > > > > > These two are a single 16 bit register UNREAD_ED_ADR = 2864
> > > > > >
> > > > > > > +};
> > > > > >
> > > > > > I'm still sad that we can all know the names of all these
> > > > > > registers and yet this is writing new tables of hex values.
> > > > >
> > > > > Do you want me use call like bellow API with register names:
> > > > > CCI_REG16_LE(0x30d8);
> > > > > cci_write();
> > > > > cci_multi_reg_write();
> > > > > devm_cci_regmap_init_i2c();
> > > >
> > > >
> > > > Yes please, I would want that very much. I'm not very good at
> > > > reading and storing hex values in my head! That's why I broke down
> > > > the above registers to strings and decimal values.
> > >
> > > I agree, it'd be good to do these while changing the driver now. I
> > > think it could be done after adding the new modes, now that the
> > > patches already exist.
> >
> > That's ok with me! Either way I'm happy to see the drivers are getting
> > cleaned up!
> >
> > >
> > > >
> > > >
> > > > The discussions at
> > > >
> https://lore.kernel.org/all/PH0PR11MB5611FD22CF6E12F7226FA9C081E12
> > > > @PH0PR11MB5611.namprd11.prod.outlook.com/
> > > > reports the full datasheet, and I stated:
> > > >
> > > >
> > > > > > > This is an enormous amount of duplicated data that could be
> > > > > > > factored out.
> > > > > > >
> > > > > > > These are also /very/ common against the existing mode
> > > > > > > register tables too.
> > > > > > >
> > > > > > > I think several things need to happen in this driver:
> > > > > > >
> > > > > > >  1. It should be converted to use the CCI helpers.
> > > > > > >  2. Whereever identifiable, the register names should be
> > > > > > > used instead of
> > > > > > >     just the addresses.
> > > > > > >  3. The common factors of these tables should be de-duplicated.
> > > > > > >
> > > > > > > In your additions you only have differences in the following
> > > > > > > registers from those entire tables:
> > > >
> > > > You replied with
> > > >
> > > > > >
> > > > > > I will try to optimize camera resolution array register value
> > > > > > usage by writing common register array values.
> > > >
> > > > which you have done (point 3), and is great progress in the series.
> > > >
> > > > Further down in the thread I stated:
> > > >
> > > >
> > > > > > >  4. And ideally - the differences which determine the modes
> > > > > > > should be
> > > > > > >     factored out to calculations so that we are not writing
> > > > > > > out large
> > > > > > >     tables just to write a parameterised frame size.
> > > > > > >
> > > > > > >
> > > > > > > I would beleive that at least steps 1 and 3 would be
> > > > > > > achievable, 2 and 4 would depend upon access to the datasheet.
> > > > > > >
> > > >
> > > >
> > > > I still believe steps 1 is important to this development. You have
> > > > done step 3 I think. And now both step 2 and (later) step 4 are
> > > > possible as we have the datasheet.
> > >
> > > In this case the datasheet doesn't appear to be documenting the PLL.
> >
> > :-(
> >
> > But at least we will have enough to handle all the vmax/and cropping
> > more directly.
> 
> I haven't fully analysed the datasheet, but isn't this just another Sony Starvis
> sensor, working in the same way as imx415 and imx290?
> 
> I don't think you can reasonably treat it as generic PLLs without effectively
> reverse engineering the hardware.
> INCK gets handled by the registers as specified in "INCK Setting" to get the
> source clocks consistent regardless of INCK.
> Source clock vs link frequency registers need to be teased out of the "INCK
> Setting Register" table. Quick analysis:
> - BCWAIT_TIME, CP_WAIT, INCKSEL2, INCKSEL3, and INCKSEL4 only change
> with INCK.
> - PLL_IF_GC and SYS_MODE only change with link frequency.
> - INCKSEL1 is the awkward one if there is a need to support the 1188Mbit/s
> data rate, otherwise it only changes with INCK.
> 
> The pixel rate stays the same for all modes (binning may be the exception
> here) HMAX (V4L2_CID_HBLANK) is changed to vary the line time.
> Whilst VMAX is listed as a constant for each mode, it can be changed to alter
> frame rate.
> 
> Link frequency is independent of resolution, but HMAX has to be set to ensure
> that we don't overflow the FIFO between array and CSI block.
> 
> 
> Is there anyone selling an IMX334 module for use with SBCs at a sensible
> price? I'm always up for tinkering with sensors, even if I'm not meant to be!
> 
>   Dave
> 
> > --
> > Kieran
> >
> >
> > >
> > > --
> > > Regards,
> > >
> > > Sakari Ailus
> >

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