From: Aradhya Bhatia a-bhatia1@ti.com

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") Cc: stable@vger.kernel.org Tested-by: Dominik Haller d.haller@phytec.de Reviewed-by: Tomi Valkeinen tomi.valkeinen@ideasonboard.com Tested-by: Tomi Valkeinen tomi.valkeinen@ideasonboard.com Signed-off-by: Aradhya Bhatia a-bhatia1@ti.com Signed-off-by: Aradhya Bhatia aradhya.bhatia@linux.dev --- drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c | 15 ++++++++++++++- 1 file changed, 14 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 741d676b8266..93c3d5f1651d 100644 --- a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c +++ b/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c @@ -776,7 +776,7 @@ static void cdns_dsi_bridge_atomic_enable(struct drm_bridge *bridge, struct drm_connector *connector; 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)) @@ -796,6 +796,19 @@ static void cdns_dsi_bridge_atomic_enable(struct drm_bridge *bridge, cdns_dsi_hs_init(dsi); cdns_dsi_init_link(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); + + if (readl_poll_timeout(dsi->regs + MCTL_MAIN_STS, status, + (tmp == (status & tmp)), 100, 500000)) + dev_err(dsi->base.dev, + "Timed Out: DSI-DPhy Clock and Data Lanes not ready.\n"); + 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),