Re: [PATCH v4] media: ov5640: select the MIPI lane mode from the endpoint lane count

[johannes.goede@oss.qualcomm.com]

Hi,

On 11-Aug-26 11:17, Jason Yang via B4 Relay wrote:
> From: Jason Yang <jason98166@gmail.com>
> 
> ov5640_set_stream_mipi() always programs IO_MIPI_CTRL00 with 0x45,
> which selects the two data lane mode: the number of data lanes
> described in the devicetree endpoint only feeds the sensor's clock
> tree computations, so a module wired with one data lane starts
> streaming in two lane mode and the receiver never assembles a
> frame.
> 
> Take the lane mode from the endpoint instead. The field encodes
> the lane count directly - 001 for one lane, 010 for two - per the
> current sensor manual (version 2.33). The 2.03 manual documented
> 000/001 for one/two lanes; OmniVision corrected the table in
> version 2.1, which is why the long-standing comment here found 001
> unusable for two lanes and validated 010 instead.
> 
> The power-up path also programs a two data lane mode, but that
> value is overwritten when streaming starts, so it is left alone.
> 
> Tested with a single data lane module on an i.MX8MP board
> (imx-mipi-csis receiver), where the unpatched value produces no
> frames at all, and on an RK3588 board.
> 
> Fixes: 19a81c1426c1 ("[media] add Omnivision OV5640 sensor driver")
> Cc: stable@vger.kernel.org
> Signed-off-by: Jason Yang <jason98166@gmail.com>
> Assisted-by: Claude:claude-opus-5
> ---
> Changes in v4:
> - Keep the lane count programmed also while the interface is
>   disabled, toggling only the enable bits (Hans Verkuil); with one
>   data lane the disable value becomes 0x20 instead of 0x40.
> - Link to v3: https://lore.kernel.org/r/20260811-ov5640-1lane-v1-v3-1-ae476eaf5024@gmail.com
> 
> Changes in v3:
> - Inline the lane count in the write instead of going through a
>   local variable (Sakari Ailus).
> - Link to v2: https://lore.kernel.org/r/20260811-ov5640-1lane-v1-v2-1-65205ae86feb@gmail.com
> 
> Changes in v2:
> - Compute the register value from the lane count in the single
>   write instead of branching on it (Sakari Ailus), with the count
>   in a local variable to stay within 80 columns; the programmed
>   values are unchanged, 0x25 for one lane and 0x45 for two.
> - Request a normal stable backport rather than opting out of
>   AUTOSEL (Sakari Ailus).
> - Drop the quotes around the function name in the reference from
>   ov5640_set_power_mipi() (Sakari Ailus).
> - Link to v1: https://lore.kernel.org/r/20260811-ov5640-1lane-v1-v1-1-79699457ce13@gmail.com
> ---
>  drivers/media/i2c/ov5640.c | 18 ++++++------------
>  1 file changed, 6 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/media/i2c/ov5640.c b/drivers/media/i2c/ov5640.c
> index 8deb5f5501fa..a99e4edb6a75 100644
> --- a/drivers/media/i2c/ov5640.c
> +++ b/drivers/media/i2c/ov5640.c
> @@ -1831,22 +1831,16 @@ static int ov5640_set_stream_mipi(struct ov5640_dev *sensor, bool on)
>  	/*
>  	 * Enable/disable the MIPI interface
>  	 *
> -	 * 0x300e = on ? 0x45 : 0x40
> -	 *
> -	 * FIXME: the sensor manual (version 2.03) reports
> -	 * [7:5] = 000  : 1 data lane mode
> -	 * [7:5] = 001  : 2 data lanes mode
> -	 * But this settings do not work, while the following ones
> -	 * have been validated for 2 data lanes mode.
> -	 *
> -	 * [7:5] = 010	: 2 data lanes mode
> +	 * [7:5]	: data lane count, 001 for one lane and 010 for two,
> +	 *		  per version 2.33 of the sensor manual
>  	 * [4] = 0	: Power up MIPI HS Tx
>  	 * [3] = 0	: Power up MIPI LS Rx
>  	 * [2] = 1/0	: MIPI interface enable/disable
>  	 * [1:0] = 01/00: FIXME: 'debug'
>  	 */
>  	ret = ov5640_write_reg(sensor, OV5640_REG_IO_MIPI_CTRL00,
> -			       on ? 0x45 : 0x40);
> +			       sensor->ep.bus.mipi_csi2.num_data_lanes << 5 |
> +			       (on ? 0x05 : 0x0));
>  	if (ret)
>  		return ret;
>  
> @@ -2535,8 +2529,8 @@ static int ov5640_set_power_mipi(struct ov5640_dev *sensor, bool on)
>  	 * Power up MIPI HS Tx and LS Rx; 2 data lanes mode
>  	 *
>  	 * 0x300e = 0x40
> -	 * [7:5] = 010	: 2 data lanes mode (see FIXME note in
> -	 *		  "ov5640_set_stream_mipi()")
> +	 * [7:5] = 010	: 2 data lanes mode (see the note in
> +	 *		  ov5640_set_stream_mipi())
>  	 * [4] = 0	: Power up MIPI HS Tx
>  	 * [3] = 0	: Power up MIPI LS Rx
>  	 * [2] = 1	: MIPI interface enabled

Sorry that I missed this previously, but should this not also
write the correct lane-count right away, rather then waiting
with fixing the line-count for 1 lane configs till we hit
ov5640_set_stream_mipi() ?

Regards,

Hans