On 2023-05-19 14:17:30, Jessica Zhang wrote:
> Currently, slice_count is being used to calculate word count and
> pkt_per_line. In downstream, these values are calculated using slice per
> packet, which is not the same as slice_count.
>
> Slice count represents the number of soft slices per interface, and its
> value will not always match that of slice per packet. For example, it is
> possible to have cases where there are multiple soft slices per interface
> but the panel specifies only one slice per packet.
>
> Thus, use the default value of one slice per packet and remove slice_count
> from the aforementioned calculations.
>
> Fixes: 08802f515c3c ("drm/msm/dsi: Add support for DSC configuration")
> Fixes: bc6b6ff8135c ("drm/msm/dsi: Use DSC slice(s) packet size to compute
> word count")
> Signed-off-by: Jessica Zhang <quic_jessz...@quicinc.com>
> ---
> drivers/gpu/drm/msm/dsi/dsi_host.c | 24 ++++++++++++++----------
> 1 file changed, 14 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c
> b/drivers/gpu/drm/msm/dsi/dsi_host.c
> index d04f8bbd707d..8c8858ee59ec 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
> @@ -866,18 +866,15 @@ 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);
>
> - /*
> - * If slice_count is greater than slice_per_intf
> - * then default to 1. This can happen during partial
> - * update.
> - */
> - if (dsc->slice_count > slice_per_intf)
> - dsc->slice_count = 1;
> -
> total_bytes_per_intf = dsc->slice_chunk_size * slice_per_intf;
>
> eol_byte_num = total_bytes_per_intf % 3;
> - pkt_per_line = slice_per_intf / dsc->slice_count;
> +
> + /*
> + * Default to 1 slice_per_pkt, so pkt_per_line will be equal to
> + * slice per intf.
> + */
> + pkt_per_line = slice_per_intf;
Same as the comment below, perhaps it is a good idea to clarify in the
comment here that the original value wa *multiplied by* slice_per_pkt?
Otherwise this default of 1 is "invisible".
Alternatively we could have a `const slice_per_pkt = 1;` at the top, and
have the comment (the elaborate one from below) there?
- Marijn
>
> if (is_cmd_mode) /* packet data type */
> reg =
> DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE(MIPI_DSI_DCS_LONG_WRITE);
> @@ -1001,7 +998,14 @@ static void dsi_timing_setup(struct msm_dsi_host
> *msm_host, bool is_bonded_dsi)
> if (!msm_host->dsc)
> wc = hdisplay * dsi_get_bpp(msm_host->format) / 8 + 1;
> else
> - wc = msm_host->dsc->slice_chunk_size *
> msm_host->dsc->slice_count + 1;
> + /*
> + * When DSC is enabled, WC = slice_chunk_size *
> slice_per_packet + 1.
> + * Currently, the driver only supports default value of
> slice_per_packet = 1
> + *
> + * TODO: Expand mipi_dsi_device struct to hold
> slice_per_packet info
> + * and adjust DSC math to account for
> slice_per_packet.
> + */
> + wc = msm_host->dsc->slice_chunk_size + 1;
>
> dsi_write(msm_host, REG_DSI_CMD_MDP_STREAM0_CTRL,
> DSI_CMD_MDP_STREAM0_CTRL_WORD_COUNT(wc) |
>
> --
> 2.40.1
>
