Re: [PATCH v3 12/13] drm/msm/dsi: Add support for DSC configuration

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

On 16/11/2021 09:22, Vinod Koul wrote:
> When DSC is enabled, we need to configure DSI registers accordingly and
> configure the respective stream compression registers.
> 
> Add support to calculate the register setting based on DSC params and
> timing information and configure these registers.
> 
> Signed-off-by: Vinod Koul <vkoul@kernel.org>
> ---
>   drivers/gpu/drm/msm/dsi/dsi.xml.h  |  10 +++
>   drivers/gpu/drm/msm/dsi/dsi_host.c | 113 ++++++++++++++++++++++++++++-
>   2 files changed, 122 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/msm/dsi/dsi.xml.h b/drivers/gpu/drm/msm/dsi/dsi.xml.h
> index 49b551ad1bff..c1c85df58c4b 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi.xml.h
> +++ b/drivers/gpu/drm/msm/dsi/dsi.xml.h
> @@ -706,4 +706,14 @@ static inline uint32_t DSI_VERSION_MAJOR(uint32_t val)
>   #define REG_DSI_CPHY_MODE_CTRL					0x000002d4
>   
>   
> +#define REG_DSI_VIDEO_COMPRESSION_MODE_CTRL			0x0000029c
> +
> +#define REG_DSI_VIDEO_COMPRESSION_MODE_CTRL2			0x000002a0
> +
> +#define REG_DSI_COMMAND_COMPRESSION_MODE_CTRL			0x000002a4
> +
> +#define REG_DSI_COMMAND_COMPRESSION_MODE_CTRL2			0x000002a8
> +
> +#define REG_DSI_COMMAND_COMPRESSION_MODE_CTRL3			0x000002ac
> +
>   #endif /* DSI_XML */
> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
> index 31d385d8d834..2c14c36f0b3d 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
> @@ -908,6 +908,20 @@ static void dsi_ctrl_config(struct msm_dsi_host *msm_host, bool enable,
>   		dsi_write(msm_host, REG_DSI_CPHY_MODE_CTRL, BIT(0));
>   }
>   
> +static int dsi_dsc_update_pic_dim(struct msm_display_dsc_config *dsc,
> +				  int pic_width, int pic_height)
> +{
> +	if (!dsc || !pic_width || !pic_height) {
> +		pr_err("DSI: invalid input: pic_width: %d pic_height: %d\n", pic_width, pic_height);
> +		return -EINVAL;
> +	}
> +
> +	dsc->drm->pic_width = pic_width;
> +	dsc->drm->pic_height = pic_height;
> +
> +	return 0;
> +}
> +
>   static void dsi_timing_setup(struct msm_dsi_host *msm_host, bool is_bonded_dsi)
>   {
>   	struct drm_display_mode *mode = msm_host->mode;
> @@ -940,7 +954,68 @@ static void dsi_timing_setup(struct msm_dsi_host *msm_host, bool is_bonded_dsi)
>   		hdisplay /= 2;
>   	}
>   
> +	if (msm_host->dsc) {
> +		struct msm_display_dsc_config *dsc = msm_host->dsc;
> +
> +		/* update dsc params with timing params */
> +		dsi_dsc_update_pic_dim(dsc, mode->hdisplay, mode->vdisplay);
> +		DBG("Mode Width- %d x Height %d\n", dsc->drm->pic_width, dsc->drm->pic_height);
> +
> +		/* we do the calculations for dsc parameters here so that
> +		 * panel can use these parameters
> +		 */
> +		dsi_populate_dsc_params(dsc);
> +
> +		/* Divide the display by 3 but keep back/font porch and
> +		 * pulse width same
> +		 */
> +		h_total -= hdisplay;
> +		hdisplay /= 3;
> +		h_total += hdisplay;
> +		ha_end = ha_start + hdisplay;
> +	}
> +
>   	if (msm_host->mode_flags & MIPI_DSI_MODE_VIDEO) {
> +		if (msm_host->dsc) {
> +			struct msm_display_dsc_config *dsc = msm_host->dsc;
> +			u32 reg, intf_width, slice_per_intf;
> +			u32 total_bytes_per_intf;
> +
> +			/* first calculate dsc parameters and then program
> +			 * compress mode registers
> +			 */
> +			intf_width = hdisplay;
> +			slice_per_intf = DIV_ROUND_UP(intf_width, dsc->drm->slice_width);
> +
> +			dsc->drm->slice_count = 1;
> +			dsc->bytes_in_slice = DIV_ROUND_UP(dsc->drm->slice_width * 8, 8);
> +			total_bytes_per_intf = dsc->bytes_in_slice * slice_per_intf;
> +
> +			dsc->eol_byte_num = total_bytes_per_intf % 3;
> +			dsc->pclk_per_line =  DIV_ROUND_UP(total_bytes_per_intf, 3);
> +			dsc->bytes_per_pkt = dsc->bytes_in_slice * dsc->drm->slice_count;
> +			dsc->pkt_per_line = slice_per_intf / dsc->drm->slice_count;
> +
> +			reg = dsc->bytes_per_pkt << 16;
> +			reg |= (0x0b << 8);    /* dtype of compressed image */
> +
> +			/* pkt_per_line:
> +			 * 0 == 1 pkt
> +			 * 1 == 2 pkt
> +			 * 2 == 4 pkt
> +			 * 3 pkt is not supported
> +			 * above translates to ffs() - 1
> +			 */
> +			reg |= (ffs(dsc->pkt_per_line) - 1) << 6;
> +
> +			dsc->eol_byte_num = total_bytes_per_intf % 3;
> +			reg |= dsc->eol_byte_num << 4;
> +			reg |= 1;
> +
> +			dsi_write(msm_host,
> +				  REG_DSI_VIDEO_COMPRESSION_MODE_CTRL, reg);
> +		}
> +
>   		dsi_write(msm_host, REG_DSI_ACTIVE_H,
>   			DSI_ACTIVE_H_START(ha_start) |
>   			DSI_ACTIVE_H_END(ha_end));
> @@ -959,8 +1034,40 @@ static void dsi_timing_setup(struct msm_dsi_host *msm_host, bool is_bonded_dsi)
>   			DSI_ACTIVE_VSYNC_VPOS_START(vs_start) |
>   			DSI_ACTIVE_VSYNC_VPOS_END(vs_end));
>   	} else {		/* command mode */
> +		if (msm_host->dsc) {
> +			struct msm_display_dsc_config *dsc = msm_host->dsc;
> +			u32 reg, reg_ctrl, reg_ctrl2;
> +			u32 slice_per_intf, bytes_in_slice, total_bytes_per_intf;
> +
> +			reg_ctrl = dsi_read(msm_host, REG_DSI_COMMAND_COMPRESSION_MODE_CTRL);
> +			reg_ctrl2 = dsi_read(msm_host, REG_DSI_COMMAND_COMPRESSION_MODE_CTRL2);
> +
> +			slice_per_intf = DIV_ROUND_UP(hdisplay, dsc->drm->slice_width);
> +			bytes_in_slice = DIV_ROUND_UP(dsc->drm->slice_width *
> +						      dsc->drm->bits_per_pixel, 8);
> +			dsc->drm->slice_chunk_size = bytes_in_slice;
> +			total_bytes_per_intf = dsc->bytes_in_slice * slice_per_intf;
> +			dsc->pkt_per_line = slice_per_intf / dsc->drm->slice_count;
> +
> +			reg = 0x39 << 8;
> +			reg |= ffs(dsc->pkt_per_line) << 6;
> +
> +			dsc->eol_byte_num = total_bytes_per_intf % 3;
> +			reg |= dsc->eol_byte_num << 4;
> +			reg |= 1;
> +
> +			reg_ctrl |= reg;
> +			reg_ctrl2 |= bytes_in_slice;
> +
> +			dsi_write(msm_host, REG_DSI_COMMAND_COMPRESSION_MODE_CTRL, reg);
> +			dsi_write(msm_host, REG_DSI_COMMAND_COMPRESSION_MODE_CTRL2, reg_ctrl2);
> +		}
> +
>   		/* image data and 1 byte write_memory_start cmd */
> -		wc = hdisplay * dsi_get_bpp(msm_host->format) / 8 + 1;
> +		if (!msm_host->dsc)
> +			wc = hdisplay * dsi_get_bpp(msm_host->format) / 8 + 1;
> +		else
> +			wc = mode->hdisplay / 2 + 1;
>   
>   		dsi_write(msm_host, REG_DSI_CMD_MDP_STREAM0_CTRL,
>   			DSI_CMD_MDP_STREAM0_CTRL_WORD_COUNT(wc) |
> @@ -2051,9 +2158,13 @@ int msm_dsi_host_modeset_init(struct mipi_dsi_host *host,
>   {
>   	struct msm_dsi_host *msm_host = to_msm_dsi_host(host);
>   	const struct msm_dsi_cfg_handler *cfg_hnd = msm_host->cfg_hnd;
> +	struct msm_drm_private *priv;
>   	int ret;
>   
>   	msm_host->dev = dev;
> +	priv = dev->dev_private;
> +	priv->dsc = msm_host->dsc;

I have been thinking about this piece. I highly dislike the priv->dsc 
field for multiple reasons.

Please correct me if I'm wrong, we use it for several reasons:
- to check if DSC is requested at all
- to store the dsc_mask

The DSC mask should be calculated basing on dpu_encoder_virt->hw_dsc[] 
values, so it can be removed from msm_display_dsc_config.

To check whether DSC is enabled, I'd suggest the following:

- Add use_dsc flag to struct msm_display_info.
   This way it would be generic to all possible encoders which can use DSC.

- Add struct msm_dsi_has_dsc_panel() function.
   It checks whether msm_host has ->dsc data. Feel free to change the 
name of the function to better suit your style.

- Call msm_dsi_has_dsc_panel() from _dpu_kms_initialize_dsi().
   If DSC is requested, set info->use_dsc.

- In dpu_encoder_setup store use_dsc in struct dpu_encoder_virt() and 
use it later instead of checking priv->dsc.

WDYT?


> +
>   	ret = cfg_hnd->ops->tx_buf_alloc(msm_host, SZ_4K);
>   	if (ret) {
>   		pr_err("%s: alloc tx gem obj failed, %d\n", __func__, ret);
> 


-- 
With best wishes
Dmitry