Re: [PATCH v3 08/12] media: imx8mq-mipi-csi2: Add support for i.MX8QXP

From: Laurent Pinchart
Date: Thu Mar 27 2025 - 16:38:35 EST

Hi Frank,

Thank you for the patch.

On Mon, Feb 10, 2025 at 03:59:27PM -0500, Frank Li wrote:
> Add support for i.MX8QXP, which has a dedicated control and status register
> (csr) space. Enable obtaining the second register space and initializing

s/csr/CSR/

> PHY and link settings accordingly.
>
> Add reset delay for i.MX8QXP. It needs a delay after toggle reset.
>
> Signed-off-by: Frank Li <Frank.Li@xxxxxxx>
> ---
> change from v2 to v3
> - use dedicate csr reg to control phy and link settings.
>
> Change from v1 to v2
> - change 8QM go 8QXP, 8QM will failback to 8QXP to keep consisense with
> phy drivers
> ---
> drivers/media/platform/nxp/imx8mq-mipi-csi2.c | 119 ++++++++++++++++++++++++++
> 1 file changed, 119 insertions(+)
>
> diff --git a/drivers/media/platform/nxp/imx8mq-mipi-csi2.c b/drivers/media/platform/nxp/imx8mq-mipi-csi2.c
> index b5eae56d92f49..788dabe5a0870 100644
> --- a/drivers/media/platform/nxp/imx8mq-mipi-csi2.c
> +++ b/drivers/media/platform/nxp/imx8mq-mipi-csi2.c
> @@ -89,6 +89,8 @@ struct imx8mq_plat_data {
> const char *name;
> int (*enable)(struct csi_state *state, u32 hs_settle);
> void (*disable)(struct csi_state *state);
> + bool use_reg_csr: 1;

Drop :1.

> + int reset_delay;

unsigned int reset_delay_us;

as it can't be negative, and to have more clarity on the unit.

> };
>
> /*
> @@ -169,6 +171,101 @@ static const struct imx8mq_plat_data imx8mq_data = {
> .enable = imx8mq_gpr_enable,
> };
>
> +/* -----------------------------------------------------------------------------
> + * i.MX8QXP
> + */
> +
> +#define CSI2SS_PL_CLK_INTERVAL_US 10000
> +#define CSI2SS_PL_CLK_TIMEOUT_US 100000
> +
> +#define CSI2SS_PLM_CTRL 0x0
> +#define CSI2SS_PLM_CTRL_PL_CLK_RUN BIT(31)
> +#define CSI2SS_PLM_CTRL_VSYNC_OVERRIDE BIT(9)
> +#define CSI2SS_PLM_CTRL_HSYNC_OVERRIDE BIT(10)
> +#define CSI2SS_PLM_CTRL_VALID_OVERRIDE BIT(11)
> +#define CSI2SS_PLM_CTRL_POLARITY_MASK BIT(12)

#define CSI2SS_PLM_CTRL_POLARITY BIT(12)

or POLARITY_HIGH if you prefer.

> +#define CSI2SS_PLM_CTRL_ENABLE_PL BIT(0)

Sort the bits in numerical order, the middle ones are swapped.

> +
> +#define CSI2SS_PHY_CTRL 0x4
> +#define CSI2SS_PHY_CTRL_PD BIT(22)
> +#define CSI2SS_PHY_CTRL_RTERM_SEL BIT(21)
> +#define CSI2SS_PLM_CTRL_POLARITY BIT(12)

PLM ? Bit 12 is documented as reserved in PHY_CTRL. Is this a bad copy &
paste ?

> +#define CSI2SS_PHY_CTRL_RX_HS_SETTLE_MASK GENMASK(9, 4)
> +#define CSI2SS_PHY_CTRL_CONT_CLK_MODE BIT(3)
> +#define CSI2SS_PHY_CTRL_DDRCLK_EN BIT(2)
> +#define CSI2SS_PHY_CTRL_AUTO_PD_EN BIT(1)
> +#define CSI2SS_PHY_CTRL_RX_ENABLE BIT(0)
> +
> +#define CSI2SS_DATA_TYPE 0x38

According to the reference manual, the register is called
DATA_TYPE_DISABLE_BF.

> +#define CSI2SS_DATA_TYPE_MASK GENMASK(23, 0)
> +
> +#define CSI2SS_CTRL_CLK_RESET 0x44
> +#define CSI2SS_CTRL_CLK_RESET_EN BIT(0)
> +
> +static int imx8qxp_gpr_enable(struct csi_state *state, u32 hs_settle)
> +{
> + int ret;
> + u32 val;
> +
> + /* clear format */

s/clear/Clear/

Same where applicable elsewhere.

> + regmap_clear_bits(state->phy_gpr, CSI2SS_DATA_TYPE, CSI2SS_DATA_TYPE_MASK);
> +
> + /* clear polarity */
> + regmap_clear_bits(state->phy_gpr, CSI2SS_PLM_CTRL,
> + CSI2SS_PLM_CTRL_VSYNC_OVERRIDE |
> + CSI2SS_PLM_CTRL_HSYNC_OVERRIDE |
> + CSI2SS_PLM_CTRL_VALID_OVERRIDE |
> + CSI2SS_PLM_CTRL_POLARITY_MASK);

Given that you write the full register to 0 in imx8qxp_gpr_disable(), I
think you can use regmap_write() here.

> +
> + regmap_update_bits(state->phy_gpr, CSI2SS_PHY_CTRL, CSI2SS_PHY_CTRL_RX_HS_SETTLE_MASK,
> + FIELD_PREP(CSI2SS_PHY_CTRL_RX_HS_SETTLE_MASK, hs_settle));

You need to include linux/bitfield.h for this. It can probably use
regmap_write() too, combining it with the next line.

> +
> + regmap_set_bits(state->phy_gpr, CSI2SS_PHY_CTRL,
> + CSI2SS_PHY_CTRL_RX_ENABLE | CSI2SS_PHY_CTRL_DDRCLK_EN |
> + CSI2SS_PHY_CTRL_CONT_CLK_MODE | CSI2SS_PHY_CTRL_PD |
> + CSI2SS_PHY_CTRL_RTERM_SEL | CSI2SS_PHY_CTRL_AUTO_PD_EN);
> +
> + ret = regmap_read_poll_timeout(state->phy_gpr, CSI2SS_PLM_CTRL,
> + val, !(val & CSI2SS_PLM_CTRL_PL_CLK_RUN),
> + CSI2SS_PL_CLK_INTERVAL_US,
> + CSI2SS_PL_CLK_TIMEOUT_US);

How many iterations does this typically require ?

> +
> + if (ret) {
> + dev_err(state->dev, "Timeout waiting for Pixel-Link clock");
> + return ret;
> + }
> +
> + /* Enable Pixel link Master*/

s/Master/Master /

> + regmap_set_bits(state->phy_gpr, CSI2SS_PLM_CTRL,
> + CSI2SS_PLM_CTRL_ENABLE_PL | CSI2SS_PLM_CTRL_VALID_OVERRIDE);
> +
> + /* PHY Enable */
> + regmap_clear_bits(state->phy_gpr, CSI2SS_PHY_CTRL,
> + CSI2SS_PHY_CTRL_PD | CSI2SS_PLM_CTRL_POLARITY);
> +
> + /* Release Reset */
> + regmap_set_bits(state->phy_gpr, CSI2SS_CTRL_CLK_RESET, CSI2SS_CTRL_CLK_RESET_EN);

No need to clear this bit in imx8qxp_gpr_disable() ?

> +
> + return ret;
> +}
> +
> +static void imx8qxp_gpr_disable(struct csi_state *state)
> +{
> + /* Disable Pixel Link */
> + regmap_write(state->phy_gpr, CSI2SS_PLM_CTRL, 0x0);
> +
> + /* Disable PHY */

s/ / /

> + regmap_write(state->phy_gpr, CSI2SS_PHY_CTRL, 0x0);
> +};
> +
> +static const struct imx8mq_plat_data imx8qxp_data = {
> + .name = "i.MX8QXP",
> + .enable = imx8qxp_gpr_enable,
> + .disable = imx8qxp_gpr_disable,
> + .use_reg_csr = 1,

s/1/true/

> + .reset_delay = 10000,

Is this documented somewhere ?

> +};
> +
> static const struct csi2_pix_format imx8mq_mipi_csi_formats[] = {
> /* RAW (Bayer and greyscale) formats. */
> {
> @@ -273,6 +370,8 @@ static int imx8mq_mipi_csi_sw_reset(struct csi_state *state)
> return ret;
> }
>
> + fsleep(state->pdata->reset_delay);
> +
> return 0;
> }
>
> @@ -860,6 +959,25 @@ static int imx8mq_mipi_csi_parse_dt(struct csi_state *state)
> return PTR_ERR(state->rst);
> }
>
> + if (state->pdata->use_reg_csr) {
> + const struct regmap_config regmap_config = {
> + .reg_bits = 32,
> + .val_bits = 32,
> + .reg_stride = 4,
> + };
> + void __iomem *base;
> +
> + base = devm_platform_ioremap_resource(to_platform_device(dev), 1);
> + if (IS_ERR(base))
> + return dev_err_probe(dev, IS_ERR(base), "missed csr register\n");

s/missed csr/Missing CSR/

> +
> + state->phy_gpr = devm_regmap_init_mmio(dev, base, &regmap_config);
> + if (IS_ERR(state->phy_gpr))
> + return dev_err_probe(dev, PTR_ERR(state->phy_gpr),
> + "Fail to init mmio regmap\n");

"Failed to init CSI MMIO regmap\n"

> + return 0;
> + }
> +
> ret = of_property_read_u32_array(np, "fsl,mipi-phy-gpr", out_val,
> ARRAY_SIZE(out_val));
> if (ret) {
> @@ -979,6 +1097,7 @@ static void imx8mq_mipi_csi_remove(struct platform_device *pdev)
>
> static const struct of_device_id imx8mq_mipi_csi_of_match[] = {
> { .compatible = "fsl,imx8mq-mipi-csi2", .data = &imx8mq_data },
> + { .compatible = "fsl,imx8qxp-mipi-csi2", .data = &imx8qxp_data },
> { /* sentinel */ },
> };
> MODULE_DEVICE_TABLE(of, imx8mq_mipi_csi_of_match);

--
Regards,

Laurent Pinchart