diff mbox series

[v4,06/11] drm/bridge: cdns-dsi: Wait for Clk and Data Lanes to be ready

Message ID 20240622110929.3115714-7-a-bhatia1@ti.com (mailing list archive)
State New, archived
Headers show
Series drm/bridge: cdns-dsi: Fix the color-shift issue | expand

Commit Message

Aradhya Bhatia June 22, 2024, 11:09 a.m. UTC
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(-)

Comments

Tomi Valkeinen June 26, 2024, 10:52 a.m. UTC | #1
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),
diff mbox series

Patch

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));
+
 	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),