Re: [PATCH 6/8] media: imx: imx-mipi-csis: Set PIXEL_MODE for YUV422

From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Jacopo Mondi <jacopo@jmondi.org>
Cc: slongerbeam@gmail.com, p.zabel@pengutronix.de,
	shawnguo@kernel.org, s.hauer@pengutronix.de, festevam@gmail.com,
	mchehab@kernel.org, hverkuil-cisco@xs4all.nl,
	martin.kepplinger@puri.sm, rmfrfs@gmail.com,
	xavier.roumegue@oss.nxp.com, alexander.stein@ew.tq-group.com,
	dorota.czaplejewicz@puri.sm, kernel@pengutronix.de,
	linux-imx@nxp.com, linux-media@vger.kernel.org,
	linux-staging@lists.linux.dev,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 6/8] media: imx: imx-mipi-csis: Set PIXEL_MODE for YUV422
Date: Tue, 15 Feb 2022 09:25:18 +0200	[thread overview]
Message-ID: <YgtVXkc8lcBSTLHy@pendragon.ideasonboard.com> (raw)
In-Reply-To: <20220214184318.409208-7-jacopo@jmondi.org>

Hi Jacopo,

Thank you for the patch.

On Mon, Feb 14, 2022 at 07:43:16PM +0100, Jacopo Mondi wrote:
> Bits 13 and 12 of the ISP_CONFIGn register configure the PIXEL_MODE
> which specifies the sampling size, in pixel component units, on the
> CSI-2 output data interface when data are transferred to memory.
> 
> The register description in the chip manual specifies that DUAL mode
> should be used for YUV422 data but does not clarify the reason.
> 
> Verify if other YUV formats require the same setting and what is the
> appropriate setting for RAW and sRGB formats.

If it's an action item, shouldn't it be in a TODO comment in the code
instead ?

While it shouldn't be difficult to test this in RAW8 mode, I'd leave it
for later, as I don't want to get into the rabbit hole of adding
S[RGB]{4}8_0_5X16 or S[RGB]{4}10_0_5X20 formats now :-)

> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
> Signed-off-by: Xavier Roumegue <xavier.roumegue@oss.nxp.com>
> ---
>  drivers/media/platform/imx/imx-mipi-csis.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/platform/imx/imx-mipi-csis.c b/drivers/media/platform/imx/imx-mipi-csis.c
> index f433758c8935..98a7538a6ce3 100644
> --- a/drivers/media/platform/imx/imx-mipi-csis.c
> +++ b/drivers/media/platform/imx/imx-mipi-csis.c
> @@ -173,6 +173,7 @@
>  #define MIPI_CSIS_ISPCFG_PIXEL_MODE_SINGLE	(0 << 12)
>  #define MIPI_CSIS_ISPCFG_PIXEL_MODE_DUAL	(1 << 12)
>  #define MIPI_CSIS_ISPCFG_PIXEL_MODE_QUAD	(2 << 12)	/* i.MX8M[MNP] only */
> +#define MIPI_CSIS_ISPCFG_PIXEL_MASK		(3 << 12)
>  #define MIPI_CSIS_ISPCFG_ALIGN_32BIT		BIT(11)
>  #define MIPI_CSIS_ISPCFG_FMT(fmt)		((fmt) << 2)
>  #define MIPI_CSIS_ISPCFG_FMT_MASK		(0x3f << 2)
> @@ -506,7 +507,12 @@ static void __mipi_csis_set_format(struct csi_state *state)
> 
>  	/* Color format */
>  	val = mipi_csis_read(state, MIPI_CSIS_ISP_CONFIG_CH(0));
> -	val &= ~(MIPI_CSIS_ISPCFG_ALIGN_32BIT | MIPI_CSIS_ISPCFG_FMT_MASK);
> +	val &= ~(MIPI_CSIS_ISPCFG_ALIGN_32BIT | MIPI_CSIS_ISPCFG_FMT_MASK
> +		| MIPI_CSIS_ISPCFG_PIXEL_MASK);
> +
> +	if (state->csis_fmt->data_type == MIPI_CSI2_DATA_TYPE_YUV422_8)
> +		val |= MIPI_CSIS_ISPCFG_PIXEL_MODE_DUAL;
> +
>  	val |= MIPI_CSIS_ISPCFG_FMT(state->csis_fmt->data_type);
>  	mipi_csis_write(state, MIPI_CSIS_ISP_CONFIG_CH(0), val);
> 

-- 
Regards,

Laurent Pinchart