[PATCH v2 10/18] drm/bridge: cdns-dsi: Fix event mode

[Jayesh Choudhary]

Hello Tomi,

On 02/04/25 19:00, Tomi Valkeinen wrote:
> The timings calculation gets it wrong for DSI event mode, resulting in
> too large hbp value. Fix the issue by taking into account the
> pulse/event mode difference.
> 
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen at ideasonboard.com>

Reviewed-by: Jayesh Choudhary <j-choudhary at ti.com>

> ---
>   drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c | 33 ++++++++++++++++++--------
>   1 file changed, 23 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c b/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
> index 62811631341b..9797e6faa29d 100644
> --- a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
> +++ b/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
> @@ -417,7 +417,8 @@
>   #define DSI_OUTPUT_PORT			0
>   #define DSI_INPUT_PORT(inputid)		(1 + (inputid))
>   
> -#define DSI_HBP_FRAME_OVERHEAD		12
> +#define DSI_HBP_FRAME_PULSE_OVERHEAD	12
> +#define DSI_HBP_FRAME_EVENT_OVERHEAD	16


I have also observed this 4B discrepancy for event-mode after comparing
the dsi packet sizes for each line type as per the dsi specifications.

>   #define DSI_HSA_FRAME_OVERHEAD		14
>   #define DSI_HFP_FRAME_OVERHEAD		6
>   #define DSI_HSS_VSS_VSE_FRAME_OVERHEAD	4
> @@ -503,12 +504,18 @@ static int cdns_dsi_mode2cfg(struct cdns_dsi *dsi,
>   
>   	bpp = mipi_dsi_pixel_format_to_bpp(output->dev->format);
>   
> -	dsi_cfg->hbp = dpi_to_dsi_timing(dpi_hbp + (sync_pulse ? 0 : dpi_hsa),
> -					 bpp, DSI_HBP_FRAME_OVERHEAD);
> +	if (sync_pulse) {
> +		dsi_cfg->hbp = dpi_to_dsi_timing(dpi_hbp, bpp,
> +						 DSI_HBP_FRAME_PULSE_OVERHEAD);
>   
> -	if (sync_pulse)
> -		dsi_cfg->hsa =
> -			dpi_to_dsi_timing(dpi_hsa, bpp, DSI_HSA_FRAME_OVERHEAD);
> +		dsi_cfg->hsa = dpi_to_dsi_timing(dpi_hsa, bpp,
> +						 DSI_HSA_FRAME_OVERHEAD);
> +	} else {
> +		dsi_cfg->hbp = dpi_to_dsi_timing(dpi_hbp + dpi_hsa, bpp,
> +						 DSI_HBP_FRAME_EVENT_OVERHEAD);
> +
> +		dsi_cfg->hsa = 0;
> +	}
>   
>   	dsi_cfg->hact = dpi_to_dsi_timing(dpi_hact, bpp, 0);
>   
> @@ -532,9 +539,12 @@ static int cdns_dsi_adjust_phy_config(struct cdns_dsi *dsi,
>   	unsigned int dsi_hfp_ext;
>   	unsigned int lanes = output->dev->lanes;
>   
> -	dsi_htotal = dsi_cfg->hbp + DSI_HBP_FRAME_OVERHEAD;
> -	if (output->dev->mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE)
> +	if (output->dev->mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE) {
> +		dsi_htotal = dsi_cfg->hbp + DSI_HBP_FRAME_PULSE_OVERHEAD;
>   		dsi_htotal += dsi_cfg->hsa + DSI_HSA_FRAME_OVERHEAD;
> +	} else {
> +		dsi_htotal = dsi_cfg->hbp + DSI_HBP_FRAME_EVENT_OVERHEAD;
> +	}
>   
>   	dsi_htotal += dsi_cfg->hact;
>   	dsi_htotal += dsi_cfg->hfp + DSI_HFP_FRAME_OVERHEAD;
> @@ -607,9 +617,12 @@ static int cdns_dsi_check_conf(struct cdns_dsi *dsi,
>   		return -EINVAL;
>   	}
>   
> -	dsi_hss_hsa_hse_hbp = dsi_cfg->hbp + DSI_HBP_FRAME_OVERHEAD;
> -	if (output->dev->mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE)
> +	if (output->dev->mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE) {
> +		dsi_hss_hsa_hse_hbp = dsi_cfg->hbp + DSI_HBP_FRAME_PULSE_OVERHEAD;
>   		dsi_hss_hsa_hse_hbp += dsi_cfg->hsa + DSI_HSA_FRAME_OVERHEAD;
> +	} else {
> +		dsi_hss_hsa_hse_hbp = dsi_cfg->hbp + DSI_HBP_FRAME_EVENT_OVERHEAD;
> +	}
>   
>   	/*
>   	 * Make sure DPI(HFP) > DSI(HSS+HSA+HSE+HBP) to guarantee that the FIFO
> 

Thanks,
Jayesh