Re: [PATCH v9 2/2] drm/bridge: Add NWL MIPI DSI host controller support

From: Sam Ravnborg
Date: Wed Mar 18 2020 - 17:46:53 EST


Hi Guido.

Impressive and very detailed changelog in intro mail - nice.

On Wed, Mar 18, 2020 at 04:09:08PM +0100, Guido Günther wrote:
> This adds initial support for the NWL MIPI DSI Host controller found on
> i.MX8 SoCs.
>
> It adds support for the i.MX8MQ but the same IP can be found on
> e.g. the i.MX8QXP.
>
> It has been tested on the Librem 5 devkit using mxsfb.
>
> Signed-off-by: Guido Günther <agx@xxxxxxxxxxx>
> Co-developed-by: Robert Chiras <robert.chiras@xxxxxxx>
> Signed-off-by: Robert Chiras <robert.chiras@xxxxxxx>
> Tested-by: Robert Chiras <robert.chiras@xxxxxxx>
> Tested-by: Martin Kepplinger <martin.kepplinger@xxxxxxx>
> ---
> drivers/gpu/drm/bridge/Kconfig | 16 +
> drivers/gpu/drm/bridge/Makefile | 3 +
> drivers/gpu/drm/bridge/nwl-dsi.c | 1213 ++++++++++++++++++++++++++++++
> drivers/gpu/drm/bridge/nwl-dsi.h | 144 ++++
> 4 files changed, 1376 insertions(+)
> create mode 100644 drivers/gpu/drm/bridge/nwl-dsi.c
> create mode 100644 drivers/gpu/drm/bridge/nwl-dsi.h
>
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index 8397bf72d2f3..d41d93d24f16 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -55,6 +55,22 @@ config DRM_MEGACHIPS_STDPXXXX_GE_B850V3_FW
> to DP++. This is used with the i.MX6 imx-ldb
> driver. You are likely to say N here.
>
> +config DRM_NWL_MIPI_DSI
> + tristate "Northwest Logic MIPI DSI Host controller"
> + depends on DRM
> + depends on COMMON_CLK
> + depends on OF && HAS_IOMEM
> + select DRM_KMS_HELPER
> + select DRM_MIPI_DSI
> + select DRM_PANEL_BRIDGE
> + select GENERIC_PHY_MIPI_DPHY
> + select MFD_SYSCON
> + select MULTIPLEXER
> + select REGMAP_MMIO
> + help
> + This enables the Northwest Logic MIPI DSI Host controller as
> + for example found on NXP's i.MX8 Processors.
> +
> config DRM_NXP_PTN3460
> tristate "NXP PTN3460 DP/LVDS bridge"
> depends on OF
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index 1eb5376c5d68..98581b3128a3 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -15,6 +15,9 @@ obj-$(CONFIG_DRM_TOSHIBA_TC358767) += tc358767.o
> obj-$(CONFIG_DRM_I2C_ADV7511) += adv7511/
> obj-$(CONFIG_DRM_TI_SN65DSI86) += ti-sn65dsi86.o
> obj-$(CONFIG_DRM_TI_TFP410) += ti-tfp410.o
> +obj-$(CONFIG_DRM_NWL_MIPI_DSI) += nwl-dsi.o
>
> obj-y += analogix/
> obj-y += synopsys/
> +
> +header-test-y += nwl-dsi.h
Sorry - but header-test-y support was ripped out of the kernel again.
So this line has no longer any effect.


> +
> +static void nwl_dsi_bridge_enable(struct drm_bridge *bridge)
> +{
> + struct nwl_dsi *dsi = bridge_to_dsi(bridge);
> + int ret;
> +
> + /* Step 5 from DSI reset-out instructions */
> + ret = reset_control_deassert(dsi->rst_dpi);
> + if (ret < 0)
> + DRM_DEV_ERROR(dsi->dev, "Failed to deassert DPI: %d\n", ret);
I picked this for a general comment.

We have drm_err(drm, "...", ...) which is preferred over DRM_XXX
They require a drm_device * that may not be available everywhere.

IMO not a showstopper, but should be trivial to fix (if adrm_device * is
a avaiable).

> +}
> +
> +static int nwl_dsi_bridge_attach(struct drm_bridge *bridge)
> +{
> + struct nwl_dsi *dsi = bridge_to_dsi(bridge);
> + struct drm_bridge *panel_bridge;
> + struct drm_panel *panel;
> + int ret;

This function now takes a flags argument.
In other words - the driver will not build when applied
to drm-misc-next.

> +
> + ret = drm_of_find_panel_or_bridge(dsi->dev->of_node, 1, 0, &panel,
> + &panel_bridge);
> + if (ret)
> + return ret;
> +
> + if (panel) {
> + panel_bridge = drm_panel_bridge_add(panel);
> + if (IS_ERR(panel_bridge))
> + return PTR_ERR(panel_bridge);
> + }
> + dsi->panel_bridge = panel_bridge;
> +
> + if (!dsi->panel_bridge)
> + return -EPROBE_DEFER;
> +
> + return drm_bridge_attach(bridge->encoder, dsi->panel_bridge, bridge);
> +}

Sam