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Subject: Re: [PATCH v5 08/22] media: camss: Add missing format identifiers
To:     Robert Foss <robert.foss@linaro.org>, agross@kernel.org,
        bjorn.andersson@linaro.org, todor.too@gmail.com,
        mchehab@kernel.org, robh+dt@kernel.org,
        angelogioacchino.delregno@somainline.org,
        linux-arm-msm@vger.kernel.org, linux-media@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        AngeloGioacchino Del Regno <kholk11@gmail.com>,
        Sakari Ailus <sakari.ailus@iki.fi>,
        Nicolas Boichat <drinkcat@chromium.org>
Cc:     Rob Herring <robh@kernel.org>, Tomasz Figa <tfiga@chromium.org>,
        Azam Sadiq Pasha Kapatrala Syed <akapatra@quicinc.com>,
        Sarvesh Sridutt <Sarvesh.Sridutt@smartwirelesscompute.com>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Jonathan Marek <jonathan@marek.ca>
References: <20210217112122.424236-1-robert.foss@linaro.org>
 <20210217112122.424236-9-robert.foss@linaro.org>
From:   Andrey Konovalov <andrey.konovalov@linaro.org>
Message-ID: <3e8eced2-de18-5def-c25e-b819e17b9c22@linaro.org>
Date:   Mon, 22 Feb 2021 19:26:55 +0300
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Hi Robert,

Thank you for your patch!

On 17.02.2021 14:21, Robert Foss wrote:
> The CSI-2 spec defines the following types:
>   - Data Type - Often abbreviated DT
>   - Decode Format - Often abbreviated as DF
>   - Encode Format
> 
> These definitions are as far as I can tell complete for CSI-2.
> 
> Additionally the Qualcomm internal type describing Plain Formats
> has been added. Plain formats describe the size of the pixels
> written by the RDI units to memory. PLAIN8 for example has the size
> 8 bits, and PLAIN32 32 bits. The appropriate Plain Format is
> determined by the Decode Format used. The smallest Plain Format
> that is able to contain a pixel of the used Decode Format is the
> appropriate one to use.
> 
> Signed-off-by: Robert Foss <robert.foss@linaro.org>
> ---
>   .../media/platform/qcom/camss/camss-csid.h    | 50 +++++++++++++++++++
>   1 file changed, 50 insertions(+)
> 
> diff --git a/drivers/media/platform/qcom/camss/camss-csid.h b/drivers/media/platform/qcom/camss/camss-csid.h
> index 1824b3745e10..02fc34ee8a41 100644
> --- a/drivers/media/platform/qcom/camss/camss-csid.h
> +++ b/drivers/media/platform/qcom/camss/camss-csid.h
> @@ -21,6 +21,56 @@
>   #define MSM_CSID_PAD_SRC 1
>   #define MSM_CSID_PADS_NUM 2
>   
> +#define DATA_TYPE_EMBEDDED_DATA_8BIT	0x12
> +#define DATA_TYPE_YUV420_8BIT		0x18
> +#define DATA_TYPE_YUV420_10BIT		0x19
> +#define DATA_TYPE_YUV420_8BIT_LEGACY	0x1a
> +#define DATA_TYPE_YUV420_8BIT_SHIFTED	0x1c /* Chroma Shifted Pixel Sampling */
> +#define DATA_TYPE_YUV420_10BIT_SHIFTED	0x1d /* Chroma Shifted Pixel Sampling */
> +#define DATA_TYPE_YUV422_8BIT		0x1e
> +#define DATA_TYPE_YUV422_10BIT		0x1f
> +#define DATA_TYPE_RGB444		0x20
> +#define DATA_TYPE_RGB555		0x21
> +#define DATA_TYPE_RGB565		0x22
> +#define DATA_TYPE_RGB666		0x23
> +#define DATA_TYPE_RGB888		0x24
> +#define DATA_TYPE_RAW_24BIT		0x27
> +#define DATA_TYPE_RAW_6BIT		0x28
> +#define DATA_TYPE_RAW_7BIT		0x29
> +#define DATA_TYPE_RAW_8BIT		0x2a
> +#define DATA_TYPE_RAW_10BIT		0x2b
> +#define DATA_TYPE_RAW_12BIT		0x2c
> +#define DATA_TYPE_RAW_14BIT		0x2d
> +#define DATA_TYPE_RAW_16BIT		0x2e
> +#define DATA_TYPE_RAW_20BIT		0x2f

- these look OK for me (the old MIPI spec draft I have doesn't have
   some of the data types listed above).

   As these are generic values from the MIPI standard, it could probably make
   sense to create a common header file for that someday.
   E.g. the very similar defines (same values, different names) are present in
   drivers/staging/media/atomisp/pci/isp_capture_defs.h
   But it looks like most of the current drivers don't need the MIPI data type
   defines, so not a problem at the moment.

> +
> +#define DECODE_FORMAT_UNCOMPRESSED_6_BIT	0x0
> +#define DECODE_FORMAT_UNCOMPRESSED_8_BIT	0x1
> +#define DECODE_FORMAT_UNCOMPRESSED_10_BIT	0x2
> +#define DECODE_FORMAT_UNCOMPRESSED_12_BIT	0x3
> +#define DECODE_FORMAT_UNCOMPRESSED_14_BIT	0x4
> +#define DECODE_FORMAT_UNCOMPRESSED_16_BIT	0x5
> +#define DECODE_FORMAT_UNCOMPRESSED_20_BIT	0x6
> +#define DECODE_FORMAT_DPCM_10_6_10		0x7
> +#define DECODE_FORMAT_DPCM_10_8_10		0x8
> +#define DECODE_FORMAT_DPCM_12_6_12		0x9
> +#define DECODE_FORMAT_DPCM_12_8_12		0xA
> +#define DECODE_FORMAT_DPCM_14_8_14		0xB
> +#define DECODE_FORMAT_DPCM_14_10_14		0xC
> +#define DECODE_FORMAT_USER_DEFINED		0xE
> +#define DECODE_FORMAT_PAYLOAD_ONLY		0xF

- interesting that the subset of the DECODE_FORMAT's used in
   camss-csid-4-1.c (the first four formats above - UNCOMPRESSED_6_BIT
   to UNCOMPRESSED_12_BIT ones) has the same values as the corresponding
   field in the CSID_CID_n_CFG registers - according to the public
   "APQ8016E Technical Reference Manual" [1]. So these exact DECODE_FORMAT_*
   values are written into the bits 7:4 of the hw register.
   But in [1] the values of DPCM_10_6_10 to DPCM_12_8_12 are 0x4 to 0x7
   (as the camss-csid-4-1.c doesn't support DPCM this is not an issue).
   Are the DECODE_FORMAT_* values above defined in the MIPI standard, or did
   they come from the datasheet for a particular SOC?

[1] https://developer.qualcomm.com/download/sd410/snapdragon-410e-technical-reference-manual.pdf
     page 990
> +
> +#define ENCODE_FORMAT_RAW_8_BIT		0x1
> +#define ENCODE_FORMAT_RAW_10_BIT	0x2
> +#define ENCODE_FORMAT_RAW_12_BIT	0x3
> +#define ENCODE_FORMAT_RAW_14_BIT	0x4
> +#define ENCODE_FORMAT_RAW_16_BIT	0x5

- the ENCODE_FORMAT_* defines are not used in the driver.

> +
> +#define PLAIN_FORMAT_PLAIN8	0x0 /* supports DPCM, UNCOMPRESSED_6/8_BIT */
> +#define PLAIN_FORMAT_PLAIN16	0x1 /* supports DPCM, UNCOMPRESSED_10/16_BIT */
> +#define PLAIN_FORMAT_PLAIN32	0x2 /* supports UNCOMPRESSED_20_BIT */

- the PLAIN_FORMAT_* defines are not used in the driver, but
   camss-csid-4-1.c and camss-csid-4-7.c do define there own
   CAMSS_CSID_CID_n_CFG_PLAIN_FORMAT_8 and CAMSS_CSID_CID_n_CFG_PLAIN_FORMAT_16
   (without relying on PLAIN_FORMAT_PLAIN8 or PLAIN_FORMAT_PLAIN16).

Thanks,
Andrey

> +
> +
>   enum csid_payload_mode {
>   	CSID_PAYLOAD_MODE_INCREMENTING = 0,
>   	CSID_PAYLOAD_MODE_ALTERNATING_55_AA = 1,
>