On 22/06/2024 14:09, Aradhya Bhatia wrote:
> Once the DSI Link and DSI Phy are initialized, the code needs to wait
> for Clk and Data Lanes to be ready, before continuing configuration.
> This is in accordance with the DSI Start-up procedure, found in the
> Technical Reference Manual of Texas Instrument's J721E SoC[0] which
> houses this DSI TX controller.
>
> If the previous bridge (or crtc/encoder) are configured pre-maturely,
> the input signal FIFO gets corrupt. This introduces a color-shift on the
> display.
>
> Allow the driver to wait for the clk and data lanes to get ready during
> DSI enable.
>
> [0]: See section 12.6.5.7.3 "Start-up Procedure" in J721E SoC TRM
> TRM Link: http://www.ti.com/lit/pdf/spruil1
>
> Fixes: e19233955d9e ("drm/bridge: Add Cadence DSI driver")
> Tested-by: Dominik Haller <d.haller@phytec.de>
> Signed-off-by: Aradhya Bhatia <a-bhatia1@ti.com>
> ---
> drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c b/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
> index 426f77092341..126e4bccd868 100644
> --- a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
> +++ b/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
> @@ -764,7 +764,7 @@ static void cdns_dsi_bridge_enable(struct drm_bridge *bridge)
> struct phy_configure_opts_mipi_dphy *phy_cfg = &output->phy_opts.mipi_dphy;
> unsigned long tx_byte_period;
> struct cdns_dsi_cfg dsi_cfg;
> - u32 tmp, reg_wakeup, div;
> + u32 tmp, reg_wakeup, div, status;
> int nlanes;
>
> if (WARN_ON(pm_runtime_get_sync(dsi->base.dev) < 0))
> @@ -781,6 +781,17 @@ static void cdns_dsi_bridge_enable(struct drm_bridge *bridge)
> cdns_dsi_init_link(dsi);
> cdns_dsi_hs_init(dsi);
>
> + /*
> + * Now that the DSI Link and DSI Phy are initialized,
> + * wait for the CLK and Data Lanes to be ready.
> + */
> + tmp = CLK_LANE_RDY;
> + for (int i = 0; i < nlanes; i++)
> + tmp |= DATA_LANE_RDY(i);
> +
> + WARN_ON_ONCE(readl_poll_timeout(dsi->regs + MCTL_MAIN_STS, status,
> + status & tmp, 100, 0));
I think an error print is more suitable than WARN_ON_ONCE(). Other than
that:
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Tomi
> +
> writel(HBP_LEN(dsi_cfg.hbp) | HSA_LEN(dsi_cfg.hsa),
> dsi->regs + VID_HSIZE1);
> writel(HFP_LEN(dsi_cfg.hfp) | HACT_LEN(dsi_cfg.hact),