Re: [PATCH] media: synopsys: dw-mipi-csi2rx: Fix DPHY testclr reset sequence

[Michael Riesch <michael.riesch@collabora.com>]

Hi Guoniu,

Thanks for the patch.

On 10/20/26 05:04, Guoniu Zhou wrote:
> The Synopsys DPHY datasheet recommends applying a testclr pulse at
> first power-up to reset the PHY configuration to its default values
> before any test control register is programmed.
> 
> The existing code deasserts testclr first and then asserts it, which
> is the reverse of the sequence recommended by the DPHY documentation.
> 
> Generate the required TESTCLR pulse by asserting TESTCLR, waiting
> for the required pulse width, and then deasserting it.
> 
> Fixes: ec40b431f0ab ("media: synopsys: csi2rx: add i.MX93 support")
> Signed-off-by: Guoniu Zhou <guoniu.zhou@oss.nxp.com>

Acked-by: Michael Riesch <michael.riesch@collabora.com>

Best regards,
Michael

> ---
>  drivers/media/platform/synopsys/dw-mipi-csi2rx.c | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/media/platform/synopsys/dw-mipi-csi2rx.c b/drivers/media/platform/synopsys/dw-mipi-csi2rx.c
> index b7247d597c9c..b9f7ba25bd3b 100644
> --- a/drivers/media/platform/synopsys/dw-mipi-csi2rx.c
> +++ b/drivers/media/platform/synopsys/dw-mipi-csi2rx.c
> @@ -830,18 +830,23 @@ static void imx93_csi2rx_dphy_assert_reset(struct dw_mipi_csi2rx_device *csi2)
>  {
>  	u32 val;
>  
> -	/* Release Synopsys DPHY test codes from reset */
> +	/* Put PHY in shutdown mode for configuration */
>  	dw_mipi_csi2rx_write(csi2, DW_MIPI_CSI2RX_DPHY_RSTZ, 0);
>  	dw_mipi_csi2rx_write(csi2, DW_MIPI_CSI2RX_PHY_SHUTDOWNZ, 0);
>  
> +	/*
> +	 * Apply testclr pulse to load analog programmability defaults
> +	 * and release the test interface for configuration.
> +	 */
>  	val = dw_mipi_csi2rx_read(csi2, DW_MIPI_CSI2RX_PHY_TST_CTRL0);
> -	val &= ~DPHY_TEST_CTRL0_TEST_CLR;
> +	val |= DPHY_TEST_CTRL0_TEST_CLR;
>  	dw_mipi_csi2rx_write(csi2, DW_MIPI_CSI2RX_PHY_TST_CTRL0, val);
>  
> -	val = dw_mipi_csi2rx_read(csi2, DW_MIPI_CSI2RX_PHY_TST_CTRL0);
>  	/* Wait for at least 15ns */
>  	ndelay(15);
> -	val |= DPHY_TEST_CTRL0_TEST_CLR;
> +
> +	val = dw_mipi_csi2rx_read(csi2, DW_MIPI_CSI2RX_PHY_TST_CTRL0);
> +	val &= ~DPHY_TEST_CTRL0_TEST_CLR;
>  	dw_mipi_csi2rx_write(csi2, DW_MIPI_CSI2RX_PHY_TST_CTRL0, val);
>  }
>  
> 
> ---
> base-commit: d7e7bca7169873b46e857c025c10f3336c1258d8
> change-id: 20261020-dw-csi2rx-6225697f45bb
> 
> Best regards,