Re: [PATCH RFC v2 5/6] drm/msm/dsi: Use MSM and DRM DSC helper methods

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

On 31/03/2023 21:49, Jessica Zhang wrote:
> Use MSM and DRM DSC helper methods to configure DSC for DSI.
> 
> Changes in V2:
> - *_calculate_initial_scale_value --> *_set_initial_scale_value
> - Split pkt_per_line and eol_byte_num changes to a separate patch
> - Moved pclk_per_line calculation to hdisplay adjustment in `if (dsc)`
>    block of dsi_update_dsc_timing()
> 
> Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
> ---
>   drivers/gpu/drm/msm/dsi/dsi_host.c | 11 ++++++++---
>   1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
> index 74d38f90398a..b7ab81737473 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
> @@ -28,6 +28,7 @@
>   #include "dsi.xml.h"
>   #include "sfpb.xml.h"
>   #include "dsi_cfg.h"
> +#include "msm_dsc_helper.h"
>   #include "msm_kms.h"
>   #include "msm_gem.h"
>   #include "phy/dsi_phy.h"
> @@ -848,7 +849,7 @@ static void dsi_update_dsc_timing(struct msm_dsi_host *msm_host, bool is_cmd_mod
>   	/* first calculate dsc parameters and then program
>   	 * compress mode registers
>   	 */
> -	slice_per_intf = DIV_ROUND_UP(hdisplay, dsc->slice_width);
> +	slice_per_intf = msm_dsc_get_slice_per_intf(dsc, hdisplay);
>   
>   	/*
>   	 * If slice_count is greater than slice_per_intf
> @@ -951,7 +952,11 @@ static void dsi_timing_setup(struct msm_dsi_host *msm_host, bool is_bonded_dsi)
>   		 * pulse width same
>   		 */
>   		h_total -= hdisplay;
> -		hdisplay /= 3;
> +		if (msm_host->mode_flags & MIPI_DSI_MODE_VIDEO)
> +			hdisplay = msm_dsc_get_uncompressed_pclk_per_line(dsc, hdisplay,
> +					dsi_get_bpp(msm_host->format)) / 3;
> +		else
> +			hdisplay /= 3;
>   		h_total += hdisplay;
>   		ha_end = ha_start + hdisplay;

This chunk changes the calculated value (two other are mere updates to 
use new functions). Please move it to a separate patch, add proper 
description/justification and possibly a Fixes tag, if the original code 
was incorrect.

>   	}
> @@ -1759,7 +1764,7 @@ static int dsi_populate_dsc_params(struct msm_dsi_host *msm_host, struct drm_dsc
>   		return ret;
>   	}
>   
> -	dsc->initial_scale_value = 32;
> +	drm_dsc_set_initial_scale_value(dsc);
>   	dsc->line_buf_depth = dsc->bits_per_component + 1;
>   
>   	return drm_dsc_compute_rc_parameters(dsc);
> 

-- 
With best wishes
Dmitry