Re: [PATCH v3 5/6] drm/msm/dsi: update hdisplay calculation for dsi_timing_setup

[Abhinav Kumar <quic_abhinavk@quicinc.com>]

On 4/4/2023 4:56 PM, Jessica Zhang wrote:
> hdisplay for compressed images should be calculated as bytes_per_slice *
> slice_count. Thus, use MSM DSC helper to calculate hdisplay for
> dsi_timing_setup instead of directly using mode->hdisplay.
> 
> Changes in v3:
> - Split from previous patch
> - Initialized hdisplay as uncompressed pclk per line at the beginning of
>    dsi_timing_setup as to not break dual DSI calculations
> 
> Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
> ---
>   drivers/gpu/drm/msm/dsi/dsi_host.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
> index 6a6218a9655f..9c33060e4c29 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
> @@ -912,6 +912,9 @@ static void dsi_timing_setup(struct msm_dsi_host *msm_host, bool is_bonded_dsi)
>   
>   	DBG("");
>   
> +	if (msm_host->dsc)
> +		hdisplay = msm_dsc_get_uncompressed_pclk_per_intf(msm_host->dsc);
> +

bonded-dsi with DSC is really not a tested configuration. If you move 
this line to before the if (is_bonded_dsi), then you will be dividing /2 
on a compressed value. That wont make sense.

I would still move this back to the if (msm_host->dsc) that way, 
bonded_dsi first divides hdisplay/2 on an uncompressed mode->hdisplay 
then DSC does its math on top of that.

>   	/*
>   	 * For bonded DSI mode, the current DRM mode has
>   	 * the complete width of the panel. Since, the complete
>