Re: [PATCH v3 00/12] media: ov5640: Misc cleanup and improvements

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Hi Maxime & all OV5640 stakeholders,

I've just pushed a new patchset also related to rate/pixel clock 
handling [1], based on your V3 great work:
 >    media: ov5640: Adjust the clock based on the expected rate
 >    media: ov5640: Remove the clocks registers initialization
 >    media: ov5640: Remove redundant defines
 >    media: ov5640: Remove redundant register setup
 >    media: ov5640: Compute the clock rate at runtime
 >    media: ov5640: Remove pixel clock rates
 >    media: ov5640: Enhance FPS handling

This is working perfectly fine on my parallel setup and allows me to 
well support VGA@30fps (instead 27) and also support XGA(1024x768)@15fps 
that I never seen working before.
So at least for the parallel setup, this serie is working fine for all 
the discrete resolutions and framerate exposed by the driver for the moment:
* QCIF 176x144 15/30fps
* QVGA 320x240 15/30fps
* VGA 640x480 15/30fps
* 480p 720x480 15/30fps
* XGA 1024x768 15/30fps
* 720p 1280x720 15/30fps
* 1080p 1920x1080 15/30fps
* 5Mp 2592x1944 15fps

Moreover I'm not clear on relationship between rate and pixel clock 
frequency.
I've understood that to DVP_PCLK_DIVIDER (0x3824) register
and VFIFO_CTRL0C (0x460c) affects the effective pixel clock frequency.
All the resolutions up to 720x576 are forcing a manual value of 2 for 
divider (0x460c=0x22), but including 720p and more, the divider value is 
controlled by "auto-mode" (0x460c=0x20)... from what I measured and
understood, for those resolutions, the divider must be set to 1 in order 
that your rate computation match the effective pixel clock on output, 
see [2].

So I wonder if this PCLK divider register should be included
or not into your rate computation, what do you think ?


[1] OV5640: reduce rate according to maximum pixel clock 
https://www.spinics.net/lists/linux-media/msg140958.html:
[2] media: ov5640: move parallel port pixel clock divider out of 
registers set https://www.spinics.net/lists/linux-media/msg140960.html

BR,
Hugues.

On 05/17/2018 10:53 AM, Maxime Ripard wrote:
> Hi,
> 
> Here is a "small" series that mostly cleans up the ov5640 driver code,
> slowly getting rid of the big data array for more understandable code
> (hopefully).
> 
> The biggest addition would be the clock rate computation at runtime,
> instead of relying on those arrays to setup the clock tree
> properly. As a side effect, it fixes the framerate that was off by
> around 10% on the smaller resolutions, and we now support 60fps.
> 
> This also introduces a bunch of new features.
> 
> Let me know what you think,
> Maxime
> 
> Changes from v2:
>    - Rebased on latest Sakari PR
>    - Fixed the issues reported by Hugues: improper FPS returned for
>      formats, improper rounding of the FPS, some with his suggestions,
>      some by simplifying the logic.
>    - Expanded the clock tree comments based on the feedback from Samuel
>      Bobrowicz and Loic Poulain
>    - Merged some of the changes made by Samuel Bobrowicz to fix the
>      MIPI rate computation, fix the call sites of the
>      ov5640_set_timings function, the auto-exposure calculation call,
>      etc.
>    - Split the patches into smaller ones in order to make it more
>      readable (hopefully)
> 
> Changes from v1:
>    - Integrated Hugues' suggestions to fix v4l2-compliance
>    - Fixed the bus width with JPEG
>    - Dropped the clock rate calculation loops for something simpler as
>      suggested by Sakari
>    - Cache the exposure value instead of using the control value
>    - Rebased on top of 4.17
> 
> Maxime Ripard (11):
>    media: ov5640: Adjust the clock based on the expected rate
>    media: ov5640: Remove the clocks registers initialization
>    media: ov5640: Remove redundant defines
>    media: ov5640: Remove redundant register setup
>    media: ov5640: Compute the clock rate at runtime
>    media: ov5640: Remove pixel clock rates
>    media: ov5640: Enhance FPS handling
>    media: ov5640: Make the return rate type more explicit
>    media: ov5640: Make the FPS clamping / rounding more extendable
>    media: ov5640: Add 60 fps support
>    media: ov5640: Remove duplicate auto-exposure setup
> 
> Samuel Bobrowicz (1):
>    media: ov5640: Fix timings setup code
> 
>   drivers/media/i2c/ov5640.c | 701 +++++++++++++++++++++----------------
>   1 file changed, 392 insertions(+), 309 deletions(-)
> 




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