Re: [PATCH v2 5/6] drm/msm/dsi: support DSC configurations with slice_per_pkt > 1

[Jessica Zhang <quic_jesszhan@quicinc.com>]

On 11/14/2023 2:58 PM, Jonathan Marek wrote:
> Add a dsc_slice_per_pkt field to mipi_dsi_device struct and the necessary
> changes to msm driver to support this field.
> 
> Note that the removed "pkt_per_line = slice_per_intf * slice_per_pkt"
> comment is incorrect.

Hi John,

Thanks for catching the typo.

> 
> Signed-off-by: Jonathan Marek <jonathan@marek.ca>
> ---
>   drivers/gpu/drm/msm/dsi/dsi_host.c | 25 ++++++++++---------------
>   include/drm/drm_mipi_dsi.h         |  1 +
>   2 files changed, 11 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
> index 842765063b1b..892a463a7e03 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
> @@ -161,6 +161,7 @@ struct msm_dsi_host {
>   
>   	struct drm_display_mode *mode;
>   	struct drm_dsc_config *dsc;
> +	unsigned int dsc_slice_per_pkt;
>   
>   	/* connected device info */
>   	unsigned int channel;
> @@ -857,17 +858,10 @@ static void dsi_update_dsc_timing(struct msm_dsi_host *msm_host, bool is_cmd_mod
>   	slice_per_intf = msm_dsc_get_slices_per_intf(dsc, hdisplay);
>   
>   	total_bytes_per_intf = dsc->slice_chunk_size * slice_per_intf;
> -	bytes_per_pkt = dsc->slice_chunk_size; /* * slice_per_pkt; */
> +	bytes_per_pkt = dsc->slice_chunk_size * msm_host->dsc_slice_per_pkt;
>   
>   	eol_byte_num = total_bytes_per_intf % 3;
> -
> -	/*
> -	 * Typically, pkt_per_line = slice_per_intf * slice_per_pkt.
> -	 *
> -	 * Since the current driver only supports slice_per_pkt = 1,
> -	 * pkt_per_line will be equal to slice per intf for now.
> -	 */
> -	pkt_per_line = slice_per_intf;
> +	pkt_per_line = slice_per_intf / msm_host->dsc_slice_per_pkt;
>   
>   	if (is_cmd_mode) /* packet data type */
>   		reg = DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE(MIPI_DSI_DCS_LONG_WRITE);
> @@ -1004,12 +998,8 @@ static void dsi_timing_setup(struct msm_dsi_host *msm_host, bool is_bonded_dsi)
>   		else
>   			/*
>   			 * When DSC is enabled, WC = slice_chunk_size * slice_per_pkt + 1.
> -			 * Currently, the driver only supports default value of slice_per_pkt = 1
> -			 *
> -			 * TODO: Expand mipi_dsi_device struct to hold slice_per_pkt info
> -			 *       and adjust DSC math to account for slice_per_pkt.
>   			 */
> -			wc = msm_host->dsc->slice_chunk_size + 1;
> +			wc = msm_host->dsc->slice_chunk_size * msm_host->dsc_slice_per_pkt + 1;

Maybe we can reuse bytes_per_pkt here.

>   
>   		dsi_write(msm_host, REG_DSI_CMD_MDP_STREAM0_CTRL,
>   			DSI_CMD_MDP_STREAM0_CTRL_WORD_COUNT(wc) |
> @@ -1636,8 +1626,13 @@ static int dsi_host_attach(struct mipi_dsi_host *host,
>   	msm_host->lanes = dsi->lanes;
>   	msm_host->format = dsi->format;
>   	msm_host->mode_flags = dsi->mode_flags;
> -	if (dsi->dsc)
> +	if (dsi->dsc) {
>   		msm_host->dsc = dsi->dsc;
> +		msm_host->dsc_slice_per_pkt = dsi->dsc_slice_per_pkt;
> +		/* for backwards compatibility, assume 1 if not set */
> +		if (!msm_host->dsc_slice_per_pkt)
> +			msm_host->dsc_slice_per_pkt = 1;
> +	}
>   
>   	/* Some gpios defined in panel DT need to be controlled by host */
>   	ret = dsi_host_init_panel_gpios(msm_host, &dsi->dev);
> diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
> index c9df0407980c..3e32fa52d94b 100644
> --- a/include/drm/drm_mipi_dsi.h
> +++ b/include/drm/drm_mipi_dsi.h
> @@ -193,6 +193,7 @@ struct mipi_dsi_device {
>   	unsigned long hs_rate;
>   	unsigned long lp_rate;
>   	struct drm_dsc_config *dsc;

Any reason for not putting this in drm_dsc_config?

Thanks,

Jessica Zhang

> +	unsigned int dsc_slice_per_pkt;
>   };
>   
>   #define MIPI_DSI_MODULE_PREFIX "mipi-dsi:"
> -- 
> 2.26.1
>